/diy/ - Do It Yourself

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DIY - /ohm/ electronics thread Anonymous Sat Sep 26 10:05:25 2015 No.880229 [Reply] [Original]

What happened to the /ohm/ thread?

Can someone tell me what band this is supposed to receive?

also, what are the BR components?

Anonymous Sat Sep 26 10:12:41 2015 No.880231

the antenna is called FM17 which is probably a clue. the BRs are metal packages that contain two coils and 2 caps; the coils usually have a ferrite slug that you can adjust, to tune it. they're usually used as tuned IF transformers, but other functions are possible.

Anonymous Sat Sep 26 10:33:47 2015 No.880237

>>880229
>What happened to the /ohm/ thread
Died of old age.
>what band this is supposed to receive
It's an AM radio, most likely for medium waves. Exact range depends on component values which aren't indicated.
>what are the BR components
Multiple different components are marked BR something: inductors, variable capacitors, IF transformers.

>>	Anonymous Sat Sep 26 20:07:28 2015 No.880452 >>880229 the if local oscillator frequency is at 456khz so its probably an am radio (535khz to 1700khz).

Anonymous Sat Sep 26 20:52:42 2015 No.880483
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I want to make an music player for different formats (mp3, flac, etc). Which microcontroller should I choose? I was thinking MSP-432( http://www.ti.com/tool/msp-exp432p401r).). I have some experience with programming the MSP430 and basic interfacing, but I was wondering if this micro was the most appropriate for handling user inputs, reading from sd card and processing the music file.

>>	Anonymous Sat Sep 26 23:22:08 2015 No.880548 >>880229 http://www.radiomuseum.org/r/heath_broadcast_receiver_br_1_b.html

>>	Anonymous Sun Sep 27 00:42:14 2015 No.880582 Faggot question here What's some good value resistors i should stock?, or should i use potentiometers in prototyping and then buy exactly what i need.

>>	Anonymous Sun Sep 27 01:01:49 2015 No.880586 >>880582 https://en.wikipedia.org/wiki/Preferred_number#Electronics

>>	Anonymous Sun Sep 27 01:07:53 2015 No.880589 >>880586 Wish i understood that thing m8 :(

>>	Anonymous Sun Sep 27 01:12:58 2015 No.880595 >>880589 http://www.electronics2000.co.uk/data/itemsmr/res_val.php E12 Series. You won't use many of the very high ones I should think.

>>	Anonymous Sun Sep 27 01:14:12 2015 No.880598 >>880595 Thanks m9

Anonymous Sun Sep 27 15:11:59 2015 No.880792

Could I have some advice regarding workstations for electronics plus gaming setups?

I need to get my computer with 24" monitor, soldering station, power supply, tools, and space to work on in such a small area as possible due to moving together with my gf to a really cramped apartment. Anyone have any own experiences or tips regarding efficient workspace?

Anonymous Sun Sep 27 16:40:07 2015 No.880840
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Hello /ohm/, this is my 18650 haul from today. Those purple pairs are from 2.2v to 2.5v. Will they kill me horribly if I charge them? I've read somewhere that 2.5 is the lower limit. They'll be used for power banks and such.

>>	Anonymous Sun Sep 27 16:44:12 2015 No.880844 >>880582 This is what I got, works fine for me (shitty if you need precision though) ebay dot com slash itm/131504016234?_trksid=p2057872.m2749.l2649

>>	Anonymous Sun Sep 27 17:07:01 2015 No.880854 >>880229 http://lmgtfy.com/?q=heathkit+br-1 it says what it is right on the schematic "Broadcast Receiver" that means AM.

>>	Anonymous Sun Sep 27 17:22:21 2015 No.880862 >>880840 what's the capacitance?

>>	Anonymous Sun Sep 27 17:24:58 2015 No.880867 >>880862 Rated 2200, charging them now. The red ones should be close to that, they came from a pretty recent (not windows XP) MSI laptop.

>>	Anonymous Sun Sep 27 17:25:55 2015 No.880868 >>880867 uF? mF? F?

>>	Anonymous Sun Sep 27 17:26:08 2015 No.880869 >>880862 18650s are batteries not capacitors.

>>	Anonymous Sun Sep 27 17:26:56 2015 No.880872 >>880867 >>880869 ???

>>	Anonymous Sun Sep 27 17:30:48 2015 No.880874 >>880872 The ratings are going to be in milli-amp-hours because they're batteries, not capacitors.

>>	Anonymous Sun Sep 27 17:37:15 2015 No.880880 >>880229 >band this is supposed to receive? IF transformers are 455kHz. this is standard for AM Broadcast Band receivers FM receivers usually use 10.7mHz IF transformers. USA AM Broadcast Band 530 kHz – 1710 kHz

>>	Anonymous Sun Sep 27 17:54:48 2015 No.880887 >>880840 2.2V and 2.5V means they are pretty much dead LiPos shouldn't go below 2.7V and even that is going to give you a low number of charge cycles generally you wouldn't want them to go below 3V

>>	Anonymous Sun Sep 27 18:15:50 2015 No.880899 >>880887 Well fuck. I suppose it'll have to do, as long as they don't have about 10-20 charging cycles. We'll see how it goes, the reds were 2.8-3V

>>	Anonymous Sun Sep 27 18:47:45 2015 No.880928 >>880483 You might want a faster Cortex just to make it easier. I have no experience with codecs on microcontrollers though, you probably want to write up the code first and profile it.

>>	Anonymous Sun Sep 27 22:43:27 2015 No.881042 File: 581 KB, 2448x1235, IMG_9303.jpg [View same] [iqdb] [saucenao] [google] How many henry's is this? Google brings up nothng

>>	Anonymous Sun Sep 27 23:25:51 2015 No.881056 >>881042 If you are planning to use it for something else that requires a specific inductance you may have to meter it.

Anonymous Sun Sep 27 23:46:10 2015 No.881064

If i understand correctly when you put capacitors in parallel you can add the values together for higher capacitance. Same goes for inductors and the opposite for resistors. What if all your components were made like this in an oscillator circuit? Would it work? This is coming from an anon who doesn't have a lot.

>>	Anonymous Sun Sep 27 23:53:41 2015 No.881066 >>881064 >Would it work? If you get the right value. You may be able to cut the plastic off it and vary the number of turn if you need to. The other thing to consider is there are various types of ferrite.

>>	Anonymous Sun Sep 27 23:58:18 2015 No.881068 >>881066 >plastic off it and vary the number of turn if you need to I don't understand, can you elaborate? >The other thing to consider is there are various types of ferrite. What if I just buy the same cheap as fuck brands from China

Anonymous Mon Sep 28 02:00:39 2015 No.881103

>>881064
Inductors are like resistors: series connection increases the inductance. If the inductors "see" each others, the the total inductance can be lower or higher than the calculated value.
Extra resistors in oscillator LC tanks are generally unwanted, but you can build an oscillator using either series- or parallel connected components.

Anonymous Mon Sep 28 02:23:26 2015 No.881105
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>>881068
Some of them are formed like pic related and you could cut the plastic cover off.

>What if I just buy the same cheap as fuck brands from China

Without knowing what you are trying to do with it it is hard to say.

>>	Anonymous Mon Sep 28 03:34:39 2015 No.881118 >>880483 Are you going full custom? The EVK1105 with an AVR32 is made pretty much for this. It has sd card slot, mp3 codec , color screen, headphone jack and other stuff.

Anonymous Mon Sep 28 06:25:28 2015 No.881125

>>880229

I have an old computer, I took from its way to landfill, which I want to use as my personal lab computer. Ideally I would have it running without monitor, connect to it from my laptop via USB/Ethernet/whatever and have access to its UARTs, LPTs, gameports, soundcard and other peripherals for my own tinkering purposes.

What OS would you suggest for doing this?

Main specs: 188MHz Pentium MMX CPU, 64MB RAM (the chipset reports this amout even with two 128MB DIMMs in). 3 ISA, 2 PCI slots and one ISA/PCI shared.

>>	Anonymous Mon Sep 28 07:12:26 2015 No.881130 >>881125 >UARTs, LPTs, gameports, soundcard, 3 ISA DOS 6.

Anonymous Mon Sep 28 07:58:19 2015 No.881135

>>881125
Any OS you want depending on what you want to do on the machine.

The key part is communicating. You'll want to run a USB to serial dongle from your laptop, then connect to the oldenbox via 232. Set up a terminal service on the oldenbox, then use telnet/SSH/terminal to connect to the box and make it do your bidding.

Anonymous Mon Sep 28 08:37:24 2015 No.881147

>>881125

an old PC is one of the worst choices for what you wanna do. it has quite limited I/O, and it's difficult to program. on a PC that old, it's likely that the parallel ports are only good as outputs, so you have very little in the way of inputs.

a Raspi or Arduino are 100x better suited for your purpose. the RasPi for example includes simple high-level programming languages, like Ruby, that can connect you to the internet in a few lines of code. tons of I/O, lots of sample programs to learn from, very small, very low-power, USB, modern compilers and interpreters, gigs of storage on SD cards, active community.

>>	Anonymous Mon Sep 28 08:55:41 2015 No.881154 >>881147 >it has quite limited I/O It has an old-fashioned computer bus, which is very easy to use.

Anonymous Mon Sep 28 09:00:55 2015 No.881155

>>881147
> someone asks how to do something
> yet another faggot pops in to tell OP why he's wrong instead of answering the question.
> implying you're not the cancer killing /diy/

It is his toys and time to waste, and there is still plenty to be learned from bit banging shit in and out of serial, LPT and other ports. Once he hits those walls he will not only have more knowledge under his belt about PC I/O and interfacing, but he will also understand where the limits are, and how to avoid them on his next project. This is exactly how myself (and no doubt a lot of others here) got into hardware interfacing, fucking with parallel and game ports. GTFO.

Anonymous Mon Sep 28 09:03:52 2015 No.881156

>>881154

no it isnt. first you gotta make a PCB that will fit the PCI or ISA slots exactly, then you gotta come up with a design using a shit load of tri-state buffers, and other TTL chips before you can begin your project. this requires and advanced knowledge of PC hardware and software. there's nothing easy about it, unless you've been doing it for a long time.

Anonymous Mon Sep 28 09:09:37 2015 No.881159

>>881155

you're saying, essentially, let the fucker suffer for a year or two learning obsolete technology before he realizes his mistake, and dumps the PC for a RasPi. others with more experience should not help to steer him straight coz, "Hey, I suffered through it, and so should everybody."

you're evil.

Anonymous Mon Sep 28 09:24:03 2015 No.881162

>>881156
Apart from the fact he never actually said anything about ISA interfacing..

>no it isnt. first you gotta make a PCB that will fit the PCI or ISA slots exactly

> http://www.futurlec.com/Protoboards.shtml
> ISA Bus Computer Board
> $13

> then you gotta come up with a design using a shit load of tri-state buffers, and other TTL chips before you can begin your project.
Or, you can just hang a shitload of SIPO chips (or a single 82C55) of them for all the I/O you'd ever need, see http://pe2bz.philpem.me.uk/Comm01/-%20Digital/-%20Computer/C-108-ISA-XT-Boards/ISA8255.htm

> this requires and advanced knowledge of PC hardware and software.
Really? You consider basic I/O logic and some batch scripting to poke the appropriate hardware addresses "advanced"? Are you posting from 1985?

> there's nothing easy about it,
Maybe not to you, but perhaps you should stop assuming everyone is as simple as you eh? You clearly don't have much of a clue about what you're talking about here.

>>881159
> a year or two
The fuck are you talking about? the guy could have it set up and hit the walls within 2 weeks. In the meantime he's learn about hardware level addressing to send commands to the ports, learning about port expansion and a bit of CMOS interfacing as he makes an IO expander to hang off his ports (which you'd never need to play with with a multi GPIO SBC). He'll learn about terminal interfacing and making two machines talk to each other over a standard which is common in industrial and high reliability environments (ISA and serial are still common in high end industrial and server gear), and as that other guy said, he will get a better understanding of what he needs in a SBC if he decides to take that path.

Again, if you think this is so complex that it will take "a year or two" to get through, then you maybe shouldn't be responding. That's the problem with you arduinofags. Unless you can copy pasta someone else's code, it's too damn hard, isn't it?

Anonymous Mon Sep 28 09:31:36 2015 No.881163

>>881162

i spent 3 years as a TA for a hardware course given to Computer Science students, the only hardware course they got in their 3-year program, so i have a pretty good understanding of how long it takes to get newbies up to speed on PC interfacing. you dont.

Anonymous Mon Sep 28 09:47:36 2015 No.881169

>>881163
Oh, right, so you taught a module to a class of students who likely did not even know hardware interfacing would be part of the course, likely had zero fucks to give about it, and will likely never use it again, and you're surprised they were a little slow on the uptake..?

> you dont.
Except I do, because I did, and continue to do so. Whats that saying? Those who can do, those who can't, teach? Yeah, I think that's the one I'm thinking of. If they were not proprietary boards I would dump some pics of the 16 bit ISA cards I hack together for data sampling/control of various pieces of lab equipment the company I work for makes. It is really not that hard man.

Meanwhile, I'm not here to argue, I'm here to encourage >>881125 to learn something different to the crap all you faggots are going on about. If he wants to make some shit happen on the back of a his beige box, let him do it, let him learn about it, then when he knows more (and assuming this is even more than just a passing whim for him) he will have more knowledge under his belt than he would have if he just went and brought a raspi and ripped some code off a website. If you consider that a waste of time, so be it, but don't ever discourage someone else from a learning experience.

>>	Anonymous Mon Sep 28 09:55:03 2015 No.881172 >>881169 fair enough. learning is good. but there's a concept in economics called ''opportunity cost -- the loss of potential gain from other alternatives when one alternative is chosen" you're suggesting a very high loss for no legitimate reason.

>>	Anonymous Mon Sep 28 10:09:07 2015 No.881175 >>881105 making a ultrasonic crystal oscillator for water nebulization.

>>	Anonymous Mon Sep 28 11:14:28 2015 No.881191 >>881172 >>881172 Retrocomputing rarely has any practical point. Some say DOS beige boxes are better for CNC. Regardless, that's never going to stop a man who has decided he wants to build a Z80 machine.

>>	Anonymous Mon Sep 28 12:12:49 2015 No.881210 >>881191 >DOS beige boxes are better for CNC any sauce? Interested

>>	Anonymous Mon Sep 28 13:05:28 2015 No.881235 >>881210 Not him, but DOS won't randomly interrupt your CNC control program to give time to other programs. This is nice if you're using the PC to control the CNC motors directly. No sauces, since it was a decade or two ago when I heard that.

>>	Anonymous Mon Sep 28 13:31:04 2015 No.881246 >>880868 Not that guy, but I'm guessing that he means mAH.

>>	Swifts !WiNDUPyWhk Mon Sep 28 13:32:57 2015 No.881247 >>881235 It's true. Well, right now you have Linux distributions designed specifically with CNC in mind

>>	Anonymous Mon Sep 28 13:33:20 2015 No.881248 >>881042 Based on the part number, I would guess 84 mH. That's just a guess though.

>>	Anonymous Mon Sep 28 15:25:06 2015 No.881299 File: 150 KB, 1920x1080, img_1557.png [View same] [iqdb] [saucenao] [google] Roll

>>	Anonymous Mon Sep 28 16:11:48 2015 No.881329 >>881299 99 = coat hanger walker WTF is that!? a device to walk you coat hangers? an old person walker made from coat hangers? both sound implausible.

>>	Anonymous Mon Sep 28 16:27:41 2015 No.881335 >>881299 roll

>>	Anonymous Mon Sep 28 18:14:32 2015 No.881390 >>880229 How can I reduce a 15v 5A to a 15v .5A

>>	Anonymous Mon Sep 28 18:21:51 2015 No.881395 >>881390 Why? Your device will only draw as much current as it needs

>>	Anonymous Mon Sep 28 18:24:11 2015 No.881396 >>881395 What if i have a 15v 1 A fuse if I feed it 15v 5A would it blow? or would it just not draw the current

>>	Anonymous Mon Sep 28 18:27:33 2015 No.881400 >>881396 Draw circuit. Pretty sure if your device only uses .5A, then only .5 A exists in the circuit. Which is good. If your 0.5A devices shorts and calls upon more power, your 1A fuse will blow

Anonymous Mon Sep 28 18:33:33 2015 No.881401
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>>881400

I'm trying to build a charger for a piece of test equipment. Don't have any schematics

i'm thinking transformer connected to bridge rectifier and maybe some noise filtering.

Anonymous Mon Sep 28 18:49:38 2015 No.881404

>>881400
Just to be safe, he could also put a current limiting resistor in line with the fuse. If you want 0.5A, then R=E/I, so 15V/0.5A means a 30 ohm resistor. Then, P=I*E, so 0.5A*15V=7.5 Watts.

So just put a 30 ohm, 10W resistor in line and you should be all set, assuming you don't mind generating a bunch of heat.

Anonymous Mon Sep 28 18:56:52 2015 No.881409

>>881401
Sounds ok, but your best bet is xformer to bridge rectifier to regulator (lm7815) to output. Of course, you'll want a big cap on the DC side of the rectifier (maybe 220uf to 470 uf), you'll want another cap on the input of the regulator (maybe 1uf) and you'll want a final cap on the output of the regulator (maybe 2.2uf). If the regulator is a significant distance from the bridge, throw an additional 0.1uf cap in parallel on the input of the regulator.

These are all approximate values. You could theoretically just use the +12V output from a computer power supply too.

>>	Anonymous Mon Sep 28 19:24:56 2015 No.881421 >>881401 Canon used to make a ton of bubble-jets powered from 14V @1A transformers. i see those transformers for sale for $1.50 at the thrift store all the time.

Anonymous Mon Sep 28 21:00:24 2015 No.881456

>>881404
Current doesn't work like that. If a device is 13.8V 480 mA it will draw 480mA from a 2A power supply. It will draw 480mA from a 100A power supply. All power supplies are voltage sources unless they specifically say they're current sources. That means voltage remains constant and current goes up and down with the power draw of the load.

Your math is all fucked up. What you're calculating there is how big if a resistor to put across the power supply by itself if you want to draw 0.5A from it. That's not at all the same thing as setting the maximum current a power supply is allowed to give which is unnecessary in the first place.

When components are placed in series the current through all of them is the same. When you put a resistor in series with a load what you're doing is creating a voltage drop so the load doesn't get as much voltage. This tends to reduce the current draw of the load, but not in the way you want.

Anonymous Mon Sep 28 21:25:43 2015 No.881467

>>881456
Yah, since series current is the same through all nodes in the series circuit, if you put a current limiting resistor anywhere in there (typically up front) then the current for every other device in the series circuit will be limited to however much current the resistor will allow. Have you seriously never heard of this? The reason that a device will only pull as much current as its rated for is because it has a current limiting device in it, whether that be switching (efficient) or just a current limiting resistor (inefficient). Typical values for a current limiting load like that are in the tens or single ohms, so they let a fair amount of current through without significantly impacting the voltage. Even if you don't design a current limiting element in to the circuit, you will have one anyway; namely whatever the highest resistance load is that is connected to the main series circuit.

Putting in a high wattage, low resistance element is a great way to limit current if you want to make sure that your circuit won't draw above a certain limit. Granted, for OPs case, you're right that it isn't necessary.

>>	Anonymous Mon Sep 28 22:00:32 2015 No.881484 Not sure why I didn't see this thread but could any anons help me with >>>881345

>>	Anonymous Mon Sep 28 22:51:18 2015 No.881505 >>881329 http://lmgtfy.com

Anonymous Mon Sep 28 23:44:37 2015 No.881535
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>>881467
This isn't a situation where a series resistor will work, your explaining is completely wrong, and your math is wrong in a situation where you would use a resistor.

> a device will only pull as much current as its rated for is because it has a current limiting device in it.

No. Current regulators are extremely rare and only really turn up outside of LED drivers.

Every load has a voltage vs current graph. I've attached one as an example. For resistors it's a straight line, for a more complex device like a semiconductor or OP's battery charger it will not be straight but you still get a set current draw for a given voltage. Devices are designed to operate at a set voltage, you give them that voltage and they draw the appropriate current. A 12v 1A lightbulb doesn't decide it wants to draw 50A just because you've replaced its 8 AAs with a car battery.

> high wattage, low resistance element is a great way to limit current

You are only reducing current because you're causing a voltage drop which means the other components in series are operating at a lower voltage and drawing less current. I'll show you how this will effect the battery charger. For simplicity lets assume the charger is like a 28.75 Ω resistor (13.8V/480mA)

Charger is hooked up to its 13.8V power supply and drawing 480mA like its supposed to. Now some asshat comes along and puts a 28.75 Ω resistor in series with it. The total resistance of the circuit is now 57.5Ω. The total current draw of the circuit is now 240mA (13.8V / 57.5Ω). This is the current the charger gets because current is the same through all series elements. The charger is getting HALF of the current it was supposed to get. Furthermore the 28.75 Ω resistor causes a voltage drop of 6.9v (28.75 Ω * 13.8V). Due to Kirchoff's voltage rule this means the charger is getting 13.8V - 6.9v = 6.9v, which means its not going to run at all because devices like that need the right voltage input.

Anonymous Tue Sep 29 00:21:44 2015 No.881543

>>881535
I guess that's true. If you put two current limiters in series with each other, then you will limit the current too much. On the other hand, this guy is almost undoubtedly feeding voltage in to a power supply circuit, which I'm guessing includes a regulator up front. It's unknowable how much voltage will be dropped across a 30 ohm resistor without knowing the total resistance of the primary series circuit, but as long as it doesn't drop so much voltage that the regulator doesn't have enough overhead, then the regulator is still going to provide it's output voltage, but will only be able to draw as much current as the current limiting resistor will allow.

I think you're making a good point here, and I certainly stand to learn something here, but I'm not seeing how limiting the current in to a voltage regulator is going to half the current of the circuit. It's like you say, you can feed it 1A or 100A, and it will only take what it can. And what I'm saying is if it can only take 0.5A, then why not give it exactly 0.5A? Chances are good that the input isn't leading directly to a current limiting resistor because that would be wasteful, even at only half an amp. You could feed it anything from 0.5A to 500A, so why not just stick close to the bottom of that range and only give it 0.5A?

What about if we look at this a different way. What if you took an lm317 and configured it as a constant current regulator that output 0.5 amp? In order for the half amp to be present in the final circuit, it would have to supply the voltage required in the final circuit. It's the opposite of the situation that you described, where you provide the voltage and the circuit, because of ohms law, will have 0.5 amp running through it. In this case, you provide the current and, because of ohms law, the circuit will have the correct voltage running through it. Ohms law is the same either way, so what's the difference? Not trying to fight, I guess I'm just honestly too daft to get it.

Anonymous Tue Sep 29 00:58:16 2015 No.881557

>>881543

A series resistor is appropriate in situations where you also want to reduce the voltage to a load because a resistor causes both effects. The way you calculate the appropriate resistor is different from what you've been doing.

Say you've got a 12v battery and a 9v 1A incandescent bulb (that behaves like a 9Ω resistor). On that battery the lightbulb will draw 1.33 amps (12v/9Ω), get too hot and break. You want to reduce the voltage the lightbulb is getting by 3v so it gets 9v and draws 1A. R = Vdrop / I = 3v/1A = 3Ω. You put a 3Ω in series with the battery and lightbulb.

>but I'm not seeing how limiting the current in to a voltage regulator is going to half the current of the circuit.

Most voltage regulators are LDO or step down. A regulator with a step up (boost) ability will start drawing more current when their input voltage drops but you only find those on specialized pieces of equipment that really need them. A regular battery charger isn't going to have one. It may not have a voltage regulator at all. Manufacturers like to assume customers will plug their equipment into the power supplies they tell them too.
I think you're getting confused with terms when you call a resistor a "current limiter". A resistor does put an upper limit on the current a series load can draw, but it's not the same thing as a polyswitch, fuse. These devices are designed to have very low resistances (< 1Ω) in normal so they don't cause a big voltage drop to the devices they're in series with. They are designed to increase in resistance very quickly when the current through them reaches a set limit. This is very different from a resistor that stays at a static resistance and has a linear current vs voltage drop graph.

>>	Anonymous Tue Sep 29 12:46:47 2015 No.881720 >>881299 rawl

>>	Anonymous Tue Sep 29 21:42:23 2015 No.881905 You find an uC, google the reference, and can't find anything on it. How fucked are you?

>>	Anonymous Tue Sep 29 22:32:25 2015 No.881917 >>880899 no 2.2V = dead that's it

>>	Anonymous Tue Sep 29 23:12:33 2015 No.881929 >>881299 roll?

Anonymous Tue Sep 29 23:40:48 2015 No.881944

>>881905
You can try putting in the name of the chip with various letters and numbers removed and see if you get results, but there are a lot of chips with no datasheet anywhere on the internet. Companies invent their own chips to use on their own devices and intentionally keep the information private. Reverse engineering it based on the PCB it came from is one option.

Anonymous Wed Sep 30 00:46:24 2015 No.881974

Anybody has a good guide for antennas? I have to make one for 433MHz and all I know is the length of the wire should be 1/4 the wave length. Any other methods to increase the range? I have the possibility of using more than 1 receiver, so maybe an array? Also dishes.

>>	Anonymous Wed Sep 30 00:47:44 2015 No.881975 >>881974 Increase erp

>>	Anonymous Wed Sep 30 01:48:22 2015 No.881999 >>881299 Duck gotta roll

>>	Anonymous Wed Sep 30 02:09:51 2015 No.882008 >>880483 Your chip isn't really fast enough without some really heavy duty optimizing, and it doesn't have an audio CODEC interface. You could use it with an external decoder IC.

>>	Anonymous Wed Sep 30 02:11:56 2015 No.882009 >>881125 DOS, anything modern will be a fucking pain in the arse. Not that DOS won't be a fucking pain either.

>>	Anonymous Wed Sep 30 02:15:13 2015 No.882011 >>881210 Since DOS basically does nothing, it's a good real-time platform. Many commercial RTOSes got their start on PCs.

Anonymous Wed Sep 30 02:16:01 2015 No.882012

>>881974
Whole books have been written about the topic, but for a shortish and not very technical discussion you could check the ARRL handbook.
A Yagi would be a common choice in that frequency range, if a directional antenna is ok. If not, you can increase the transmit power like the other anon said or use a better preamp in receiver.

>>	Anonymous Wed Sep 30 02:19:30 2015 No.882015 >>881944 There are also faggot companies like Broadcom who, while selling their chips to the other companies, gives the datasheets only to those who have signed their NDA.

Anonymous Wed Sep 30 04:00:45 2015 No.882044
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Hey /ohm/, anyone have much experience with bus pirates? I seem to be having some trouble updating/changing the firmware on mine, and I'm worried I may have bricked it. Everything worked as intended before I started

I have the pic related, which is a BPv3 (03b, I think). I wanted to switch to being able to use JTAG, which requires a firmware swap. Here's a timeline of what I did:
>Load BPv3 XSVF Firmware onto board via pirate loader
>Loads fine with no errors
>Lose ability to communicate via serial (offline mode)
I know it can still hear me though, as the RX/TX LEDs (can't remember which) will flicker faintly when I type
>Find out all this firmware depends on new bootloader (v4, I have v2something)
>Think "Well, better update bootloader then push new firmware in"
>Do that, all via pirate loader, cuz Linux
>Still no luck
"bootloader mode" returns BP4+ via serial after any input, though, making me suspect at least the bootloader is updated. Firmware be damned

Anonymous Wed Sep 30 04:36:59 2015 No.882051
File: 48 KB, 300x210, SOLEN-12.jpg [View same] [iqdb] [saucenao] [google]

>>881175
I expect you would want much larger inductors than that. I've worked on a few ultrasonic cleaners and they usually have big inductors wound from litz wire.

Pic related but bigger and sometimes with ferrite too.

>>	Anonymous Wed Sep 30 08:18:40 2015 No.882087 >>880867 >pretty recent (not windows XP) you know shit about batteries for sure.

Autism Man Wed Sep 30 09:00:18 2015 No.882096
File: 70 KB, 600x900, shsinx_ru098rj.jpg [View same] [iqdb] [saucenao] [google]

So I'm trying to buy some clip-on heat sinks... and thinking way too hard. Pic related is the three available options I found on amazon.

The top one is priced ridiculous. WTF?

The second one down is more realistic (roughly $2 each) but I am a cheap bastid and don't even want to pay that much....
I'm trying to find these things on aliexpress, and I can't find NUTHIN... even the cheap little "soldering kits" that have all the stuff for basic electronics soldering,,,, do not come with anything like this. I have searched for every usefaul variation I can think up and all I find is Kelvin clips. Is there a secret code name for these things in China or what???

The bottom one is another type, but I would guess (?) that it would be made of steel,,, becuz aluminum isn't that springy. And steel doesn't transfer heat nearly as well as aluminum does... does anybody use this type? Do you notice that it works less well?

I have also found elsewhere that there are ones with some kind of copper jaws. I aont ever used such a thing, but on pro-tool sites they are pretty common... Mcmaster-carr has some like this for like $12 each. I wonder, does the solder stick to the copper tho? Or is it some special alloy used to prevent that.

I may attempt to make my own if I can't find any to buy really cheap.... that way I could make some with copper and aluminum and see if the difference is worth it. :|

>>	Anonymous Wed Sep 30 09:21:45 2015 No.882102 >>882096 I use locking forceps. Au$4.50 on ebay. Has loads of other uses too.

>>	Anonymous Wed Sep 30 09:59:10 2015 No.882112 >>882044 try the forums at dangerous prototypes

Anonymous Wed Sep 30 14:56:34 2015 No.882201

>>882102
>I use locking forceps.
That would work but the thing about the aluminum clips is that they are lightweight and are easier to use in odd positions...

Also the ones I had years ago had a little groove cut into them so they'd stay clipped on a wire,,,, and neither of the ones on Amazon has that. And I remember how much better it worked with the groove than the smooth ones... :/ ......fucking crap workmanship

Anonymous Wed Sep 30 16:37:27 2015 No.882242
File: 300 KB, 862x1086, Screen Shot 2015-09-30 at 3.36.42 PM.png [View same] [iqdb] [saucenao] [google]

How does one use smt components on a breadboard?

I have a breakout board for an ssop-24 ic im using, but i have this 56nH 2% inductor i can't find in through-hole. I can just solder some hook-up wire to it, right?

also, i have a chip (si4737) that can act as digital audio slave. what search term should i be using to find a chip that can interpret i2s or dsp output from this ic?

>>	Anonymous Wed Sep 30 16:58:00 2015 No.882253 >>882242 If you need an i2s interface you search for... i2s interface! Codec interface is another good search term, but outside DSPs i2s is far more common.

Anonymous Wed Sep 30 17:05:07 2015 No.882259

>>882242
>56nH 2% inductor
Well, you could solder it across an ordinary 2-pin header. Except that you totally fuck everything with your pin header (or wires) and breadboard. Breadboard is not something you use with 56nH inductors, let alone 56nH 2% inductors.
Make a proper PCB instead or at least solder the inductor and the related components directly together with shortest possible wires.

>>	Anonymous Wed Sep 30 17:22:49 2015 No.882277 File: 31 KB, 502x368, Screen Shot 2015-09-30 at 4.21.37 PM.png [View same] [iqdb] [saucenao] [google] >>882259 it'll fuck up my breadboard? pic related.

>>	Anonymous Wed Sep 30 17:35:32 2015 No.882290 >>882277 Your breadboard will fuck up your signals.

>>	Anonymous Wed Sep 30 17:44:24 2015 No.882297 I have an headphone amp that charges via usb. With the usb disconnected the sound is crystal clear With it connected it's extremely hissy Is there a way for me to solder a capacitor or something onto a usb cable to filter the noise out?

>>	Anonymous Wed Sep 30 17:50:41 2015 No.882301 >>882297 Hissy or hummy? It sounds like you've formed a ground loop.

>>	Anonymous Wed Sep 30 17:52:16 2015 No.882302 >>882096 Just use a loose alligator clip.

>>	Anonymous Wed Sep 30 17:59:24 2015 No.882311 >>882301 its a constant hiss

>>	Anonymous Fri Oct 2 11:58:21 2015 No.883000 >>882297 the power supply and motherboard both have high-power switching elements inside them, which causes a nightmare for audio, unless they've been specifically designed to be clean.

Anonymous Fri Oct 2 12:01:47 2015 No.883003

>>882297

the power supply and motherboard both have high-power switching elements inside them, which causes a nightmare for audio, unless they've been specifically designed to be clean.

no cap or coil is gonna fix that. you'd need total galvanic isolation.

>>	Anonymous Fri Oct 2 12:34:19 2015 No.883013 >>883003 That's not going to cause the symptoms described by the OP. A grounding problem is more likely.

Anonymous Sat Oct 3 15:50:22 2015 No.883458
File: 277 KB, 961x1252, IMG_20151003_124919.jpg [View same] [iqdb] [saucenao] [google]

Halloween is just around the corner and I want to make some special effects lighting. My idea is to have a strip of LEDs that only illuminate at full brightness when you're standing next to it and that get dimmer a certain distance away from where you're standing. How do I learn what circuit components I need for each logic function? I cannot begin to grasp a relationship between a proximity sensor signal's effect on current to an LED. There are diy proximity sensors on the web but I just want to buy prebuilt ones. Any advice?

>>	Anonymous Sat Oct 3 16:23:55 2015 No.883469 >>883458 you need to convert the signal from the sensor to the signal required by the LED. depends on the sensors and leds you want to use.

Anonymous Sun Oct 4 00:57:06 2015 No.883637
File: 43 KB, 631x1424, Screenshot_2015-10-04-00-48-15~2.jpg [View same] [iqdb] [saucenao] [google]

Would connecting the positive lead of a 12v power supply to multiple places on a string of parallel lights yield any benefit or should I just connect my source to one end?

>>	Anonymous Sun Oct 4 01:00:50 2015 No.883639 >>883637 Theoretically beneficial but practically probably not worth it.

>>	Anonymous Sun Oct 4 01:06:11 2015 No.883641 >>883639 Would it be practically beneficial if I'm pulling over 200w from a 600w ATX power supply?

Anonymous Sun Oct 4 02:06:15 2015 No.883659

>>883641
If you notice the lights at the end of your string are dimmer then the ones at the start it will be fixed by adding both a positive and negative power connection to the end; especially if the string is arranged in a circle or something so the distance from the end to the power supply is shorter than the length of the string. It'll also help if you didn't use big enough wires in the string and they're melting from too much current.

>>	Anonymous Sun Oct 4 04:36:01 2015 No.883683 >>881163 You are an idiot

Anonymous Sun Oct 4 07:58:07 2015 No.883717
File: 87 KB, 1043x646, diagram.png [View same] [iqdb] [saucenao] [google]

Is there anything wrong with this microcontroller system that I have been planning. It's basically a lighting system for bicycles. At the moment it's just a plan, haven't built anything yet.

>>	Anonymous Sun Oct 4 09:35:22 2015 No.883735 >>883717 A real schematic would be more useful. Any special reason for using the AT90S2313 over the ATtiny2313?

Anonymous Sun Oct 4 10:17:24 2015 No.883744 [DELETED]

>>883637

there's one bad design choice i noticed right away: you're powering your loads thru a regulator. the only thing that accomplishes is to generate heat in the regulator, and drop the efficiency. you should drive them straight from the + of the battery instead.

Anonymous Sun Oct 4 10:19:39 2015 No.883745

>>883717

there's one bad design choice i noticed right away: you're powering your loads thru a regulator. the only thing that accomplishes is to generate heat in the regulator, and drop the efficiency. you should drive them straight from the + of the battery instead.

>>	Anonymous Sun Oct 4 11:16:22 2015 No.883754 File: 73 KB, 600x900, always getting hit on.jpg [View same] [iqdb] [saucenao] [google] :)

>>	Anonymous Sun Oct 4 11:32:35 2015 No.883756 https://gadgetory.com/index.php?route=product/category&path=66 has anyone here ever bought from these guys? i'm worried because there's no reviews anywhere on the site, nor much mention of them on google

>>	Anonymous Sun Oct 4 11:48:14 2015 No.883760 >>881299 roll

Anonymous Sun Oct 4 12:58:24 2015 No.883771

>>883745
It's a switching regulator. As long as the output voltage is low enough to compensate the regulator's losses, he wins. In this case output voltage < 6V saves power.

>>883717
The nominal minimum input voltage for both regulators is 7V and your battery goes below that before you've extracted their full charge. Probably not a problem, but you could still use better suited regulators.
Your transistors need base resistors, if you insist on using BJTs.
Your switches might work badly with the tiny pull-up current provided by AVR's inputs. Consider using external pull-up resistors.
Voltage is pretty bad indicator of the remaining charge with NiMH batteries.
Also, there are dedicated switchers for driving LEDs, if you want to increase the efficiency further.

Anonymous Sun Oct 4 14:04:57 2015 No.883798

>>883771
>It's a switching regulator. As long as the output voltage is low enough to compensate the regulator's losses, he wins

you're not thinking straight. there is no win possible by including an unnecessary regulator, even if it is 90% efficient. as for saving power, that only works if you assume the series resistors would remain unchanged.

Anonymous Sun Oct 4 14:15:20 2015 No.883803

>>883798
Let's say your LED draws 350mA at 3V.
If you feed it directly from the battery via a suitable resistor, it'll draw 350mA. Assuming 7.2V battery voltage, that's 2.5W.
If you use a switcher to drop the voltage to 4V before feeding it to the LED and the series resistor, then the LED + resistor combination draws 1.4W. Assuming 85% efficiency, power drawn from the battery is 1.6W.

Anonymous Sun Oct 4 14:22:00 2015 No.883807

>>883798
Without the switching regulator the LEDs would need larger series resistors, and dropping voltage with resistors becomes less efficient the larger the resistors are.

Say the LEDs are 3v 20mA. Powered from the 7.2v source they need series resistors to drop 4.2v. R = V / I = 4.2 / 0.02 = 210Ω. The power dissipated by each resistor would be I*I*R = 0.02*0.02*210 = 84mW

Powered from a 5v source the series resistor needs to drop 2v. R = V / I = 2/0.02 = 100Ω. The power dissipated by each resistor is I*I*R = 40mW. Since the 5v comes from a regulator we are assuming to be 90% efficient this comes to 44mW

44mW is less than 84 mW.

Anonymous Sun Oct 4 23:05:11 2015 No.883980

What kinds of flux / markers do you guise use?
I never used separate electronics flux before and decided to splurge. I use [lead] flux-core solder anyway but there's times when I think having some separate flux around would have helped.

Looking on Amazon all they seem to show is the Chemtronics pens. Some of it is no-clean, while others implies it is not, and they sell flux-cleaner pens, but I am a lazy bastid and would rather not clean.... unless the other stuff works a lot better?
,,,,
The shit's like $20 a pen with shipping. I'd rather not buy both just to find that one works dramatically better than the other. :|

>>	Anonymous Mon Oct 5 01:18:12 2015 No.884039 >>883980 I currently have a Kester 952 liquid flux pen, and a tube of MG Chemicals 8341 sticky flux. Both bought from a real distributor, none of that fake eBay shit.

Anonymous Mon Oct 5 12:43:14 2015 No.884178

I'm planning to make a robot to run ethernet cable through the air ducts in my house. I've run into a small problem though: what do I use to control it? I was planning on using either a RasPi B oregano, or an ESP8266. The Raspi seems like it might be harder to connect and power, but I wonder if the ESP has enough power to send back images from a serial camera module. Any sage words of wisdom before I cause a disaster?

Anonymous Mon Oct 5 13:00:56 2015 No.884182

I'm a programmer trying to understand what circuits and electronics are really about at a fundamental level

Is it basically constructing functions that map input voltages to output voltages? And linear circuits just map these voltages in a way that obeys the superposition principle i.e. f(a * x_1 + b * x_2) = a * f(x_1) + b * f(x_2)

And then once you get into the digital electronics realm, it seems to become more about particular arrangements of a single voltage value rather than a continuum of voltage values.

Am I completely off?

>>	Anonymous Mon Oct 5 13:26:38 2015 No.884205 >>884182 I wouldn't say you're wrong, but I'd suggest playing with some real components.

Anonymous Mon Oct 5 13:34:01 2015 No.884214

>>884182
The additive and homogeneity principles only apply to some circuits like voltage adders. Also thinking in terms of " input voltages to output voltages" doesn't really work unless you have voltage buffers everywhere. Typically the output of one part of a circuit is effected by the next part of the circuit it's going into so you usually can't treat everything as discrete independent inputs and outputs.

I'd stop trying to approach it with computer science theory. The only analogy that really works is treating it like a plumbing system where voltage is water pressure, but even that only goes so far.

Anonymous Mon Oct 5 13:44:42 2015 No.884221

>>884182
>constructing functions that map input voltages to output voltages?
Or currents or vice versa. Circuits can also have (non-insignificant) delays or memory, requiring you to consider the input and/or output history. Your circuit can also be unstable. Then there are the input and output impedances, which often prevent you from simplistically chaining functions, as they affect each other.

>And linear circuits just map these voltages in a way that obeys the superposition principle
Yes and no. You're right, but "linear circuit" is often used in the sense of "analog circuit" and they can be non-linear.

>digital electronics realm
It's a convenient simplification. But yeah, typically digital signals are considered to have two states.

>>	Anonymous Mon Oct 5 14:00:54 2015 No.884232 >>884182 It's all quantum mechanics, man. Can't you see?

Anonymous Mon Oct 5 14:39:24 2015 No.884251

Thanks for all input Anons.

>>883735
The schematic is still in the making. I planned to use the AT90S2313 chip because I have a couple of those in my inventory. They are still in good operating condition. The same goes for the LM2575 regulator IC and transistors (2N3904 & BD140 pair).

>>883745
>>883771
>>883798
>>883803
>>883807
The main reason for including a switching regulator was to generate a reasonably stable voltage level that would be more suitable for driving LEDs. I thought the LED brightness would be maintained better throughout the discharge cycle of the battery. Also, as Anons already pointed out, the output voltage of the regulator could be adjusted to fit the requirements of the LEDs.

As >>883771 pointed out, the minimum input voltage for the 78L05 regulator to generate a stable output voltage is 7 V. Maybe I should use a 8.4 V battery pack?

Anonymous Mon Oct 5 15:13:25 2015 No.884268

>>880229
Does anyone know about running ethernet cable through air ducts? I've heard some people say yeah, you can run them through air ducts as long as they're plenum-grade, which makes sense. However, I've also heard that you absolutely should not under any circumstances run any cables through your ducting under penalty of a fines, and losing your homeowners insurance for being willfully negligent. Does anyone know about this?
>Drill holes in the wall!
Would If I could.

Anonymous Mon Oct 5 15:59:04 2015 No.884286
File: 51 KB, 600x352, image.jpg [View same] [iqdb] [saucenao] [google]

Sup, diy,

I'm replacing some video Tx module with a different build — basically I have Tx chip (picrelated), camera and power supply and power stabilization covered, but I still need to do something about antenna.

So how do I go making a suitable antenna and impedance matching it — if all I've got is a good multimeter and some copper/iron wire?

>>	Anonymous Mon Oct 5 16:33:56 2015 No.884296 >>884268 Take my advice and just get a long enough cable to run along the moulding, son. Get it twice as long as you think you need it.

>>	Anonymous Mon Oct 5 16:40:32 2015 No.884299 >>884296 Why is that? Even for the return duct?

>>	Anonymous Mon Oct 5 19:10:50 2015 No.884378 If I have LEDs requiring 4V and want to use a 12V power supply should I have 3 parallel arrays in series?

>>	Anonymous Mon Oct 5 19:24:08 2015 No.884387 >>884378 You should have three LEDs in series, and groups of those in parallel.

>>	Anonymous Mon Oct 5 19:56:25 2015 No.884394 >>884286 What frequency is this thing and what type of radiation patter do you want? On what do you want to mount the antenna?

Anonymous Tue Oct 6 03:02:30 2015 No.884604

>>884394
>What frequency is this thing and what type of radiation patter do you want? On what do you want to mount the antenna?
5.8 Mhz. Dipole will do for now — I need to figure out how to match those with a simple dipole first.

I have no mounting preferences as such — i.e. free-hanging or attached to non-conductive plastic.

>>	Anonymous Tue Oct 6 03:04:01 2015 No.884607 >>884604 >Mhz Ops, I meant 5.8 Ghz.

Anonymous Tue Oct 6 03:34:13 2015 No.884613

>>884604
If it isn't particularly critical, you can use a basic dipole and attach it directly to the transmitter. Or you can use a whip. Google gives you plenty of antenna calculators if you need one.
Then there's the option of finding a premade pattern for a PCB antenna, already matched for 50R, and etching the antenna on the same PCB with the module. Or use a chip antenna, they aren't horribly expensive either. Follow the instructions for ground plane carefully with PCB and chip antennas.

Anonymous Tue Oct 6 04:33:29 2015 No.884618

>>884613
>If it isn't particularly critical, you can use a basic dipole and attach it directly to the transmitter. Or you can use a whip. Google gives you plenty of antenna calculators if you need one.
Ok, so in practical terms what should I do?
Solder two pieces of copper wire directly to both antenna + and antenna ground terminals on the chip, run them in parallel to where antenna should be, and then bend the ends of the wires into T shape measuring 26mm in length?
Somehow I get this feeling the thing will NOT be impedance matched at all…

>Then there's the option of finding a premade pattern for a PCB antenna, already matched for 50R, and etching the antenna on the same PCB with the module. Or use a chip antenna, they aren't horribly expensive either. Follow the instructions for ground plane carefully with PCB and chip antennas.
That's a bit of an overkill right now, I need to see how well simple dipole handles first.

Anonymous Tue Oct 6 04:59:29 2015 No.884623

>>884618
>Somehow I get this feeling the thing will NOT be impedance matched at all…
Let me rephrase the question somewhat:
As far as I can tell there is no way to measure an imput impedance of a simple dipole without some specialized equipment (I only have multimeter).
On the other hand, I only need to see if my antenna is matched — not measure the impedance directly.
So is there any simple way to measure how well an antenna is matched? Again, assuming I only have multimeter, basic radio parts and a video Rx with display?

Anonymous Tue Oct 6 08:22:19 2015 No.884647
File: 72 KB, 1159x677, Final pinout 1_10_15.png [View same] [iqdb] [saucenao] [google]

hi /ohm/. pic related is how i plan to fade in an out 12 LEDs for a particular project I'm doing. Simulation works fine, code seems to be working fine, Only problem is, LEDs are too dim. Like very very dim. Any idea how to make them brighter?

I'm going to use a 9V battery as power supply, replace the UNO with a Chinese nano clone. I'm using standard 5mm Blue LEDs, with forward voltage of 3.5v, current of 20 mA and 330 ohm resistors.

>>	Anonymous Tue Oct 6 09:30:11 2015 No.884665 >>884647 >Only problem is, LEDs are too dim. Like very very dim. Any idea how to make them brighter? So, what current are the LED's actually running at when they are "dim"?

>>	Anonymous Tue Oct 6 09:33:39 2015 No.884667 >>884647 With 9v over 2 3.5v LEDs and a 330 ohm resistor that leaves 2v over the resistor so a current of 6 mA. Try a 100 ohm resistor.

>>	Anonymous Tue Oct 6 10:13:01 2015 No.884684 >>884667 Yeah. I wanted to try that but someone told me that I'd be pulling too much current through the board and thus possibly damage it. Any truth to this?

>>	Anonymous Tue Oct 6 10:18:23 2015 No.884686 >>884684 Again, what currect you ARE pulling? 6 mA? 20mA? 1mA?

>>	Anonymous Tue Oct 6 10:26:07 2015 No.884696 >>884686 honestly, I have no idea. I'm very new to all this. I just tried the 100 ohm resistors and it's still very dim...

>>	Anonymous Tue Oct 6 10:28:40 2015 No.884700 >>884696 Do you have multimeter (or something) to measure current?

>>	Anonymous Tue Oct 6 10:31:24 2015 No.884702 >>884700 yes. I've never used it though. (just getting into electronics) could you tell me what to do?

>>	Anonymous Tue Oct 6 10:44:40 2015 No.884710 >>884702 Google "how to measure current with multimeter". There should be tons of vids.

>>	Anonymous Tue Oct 6 10:46:25 2015 No.884712 Hay guys, what kind of electronic chopper delivers a continuous and constant DC voltage output from a varying DC input (such as a solar panel)

>>	Anonymous Tue Oct 6 11:15:41 2015 No.884725 >>884647 Arduino uses 5V supply (even when you run it from a 9V battery) and it is not enough for 2 series connected blue LEDs.

Anonymous Tue Oct 6 11:25:55 2015 No.884730

Pretty fresh into electronics, but my little sister wants to get into electronics as well. She's 9, and wants to build a small robot for her birthday.

I've been looking around for something cheap and not shit, leaning towards following a guide for an Arduino robot. Something like this seem ideal but it's out-of-stock https://www.foxytronics.com/products/305-funduino-uno-robotics-kit

Anybody have recommended robot kits for kids to try? I'm building it with her, but some explicit guide would be helpful for us both.

>>	Anonymous Tue Oct 6 11:27:29 2015 No.884733 >>884725 so what can I do? I must have at least ten blue LEDs and they have to fade in and out. Sort of 'breathing' effect. Any ideas?

Anonymous Tue Oct 6 11:32:35 2015 No.884738

>>884733
I'm assuming these are 3v 20mA blue LEDs. Arduino's IO ports can do 5v 40mA so two blue LEDs in parallel should work. You could also use ten IO ports (one per LED). To get the voltage output you need to run LEDs in series you'd need to use the IO to switch 9v from the battery.

>>	Anonymous Tue Oct 6 12:10:25 2015 No.884754 >>884738 how do i place them in parallel? I'm not getting the layout exactly...

>>	Swifts !WiNDUPyWhk Tue Oct 6 15:12:07 2015 No.884846 Does anyone here have any experience repairing power tools? I'm going to be working at a Black&Decker/Dewalt/Stanley service center for 2 weeks and I'd like to know a little bit about what I should be expecting.

>>	Anonymous Tue Oct 6 15:50:52 2015 No.884862 >>884846 Expect to replace brushes and armatures

>>	Anonymous Wed Oct 7 00:56:50 2015 No.885084 File: 12 KB, 313x256, parallelleds.gif [View same] [iqdb] [saucenao] [google] >>884738 So I'm guessing something like this?

Anonymous Wed Oct 7 01:25:53 2015 No.885092

>>884846
This is a silly question to ask tripfag. They are DC motors, speed controllers and batteries. If this is so complex that you need to ask for protips, you should drop your trip when you ask. Last thing you want to do is ruin the reputation you have been working so hard to build here. People might even start to see you as the egotistical dramacow you actually are!

>>	Anonymous Wed Oct 7 01:48:27 2015 No.885097 >>885084 Exactly. I think you've got it now. You can do 2 leds on each 40 mA output just like this.

Anonymous Wed Oct 7 02:31:58 2015 No.885106

>>884618
Well, I said "if it isn't particularly critical". You lose some range if it isn't perfectly matched, but that's often ok. What comes to construction, you can get the impedance closer to the target value by making the dipole slightly shorter (24mm) and coaxial cable between the antenna and transmitter gives you better match than two straight wires.

>>884623
If you have a signal strength meter in your receiver, you can use it to check if your changes improved things. This is a ghetto way and changes in radiation pattern will fuck your results.
In principle, you can also build an SWR meter. They aren't complex (in principle) and Google gives you links to diy SWR meters. I'm skeptical how reliable 5.9GHz ones are, though.

>>	Anonymous Wed Oct 7 02:57:38 2015 No.885116 >>885097 Cool. Thanks very much.

Anonymous Wed Oct 7 03:02:11 2015 No.885118
File: 432 KB, 789x421, 1397234350474.png [View same] [iqdb] [saucenao] [google]

I was thinking about an easy first electronics project and I came up with a simple RC car.

I figure I could send motor signals over wireless and control the thing with my computer. Is there a really simple receiver I could use in an IC for controlling a DC motor?

>>	Anonymous Wed Oct 7 03:37:20 2015 No.885122 >>885118 It there any particular reason you want to control it from computer? It's one hell of an inconvenient way to control anything RC (without FPV, at least). And simple Rx-Tx pair with a few channels is dirt cheap these days.

Anonymous Wed Oct 7 05:42:47 2015 No.885143

>>885122
I figure it's cheaper than buying a bunch of special parts and would work about as well anyway even if I can't carry the whole setup around with me.
Really I just need a hands on project to test what I've learned and this seemed doable.

I figure you could just write a quick C program that sends a signal to a receiver that switches on or off.
Naturally I'm a little fuzzy on the details because I've never really done this before.
>And simple Rx-Tx pair with a few channels is dirt cheap these days.
That looks like the sort of thing I'm looking for, thanks.

Anonymous Wed Oct 7 05:54:49 2015 No.885146

>>885143
Can you be slightly more specific what you want as a short-term result?
If you want something that works as a decent RC car and have little experience building those it might make sense to buy something cheap (I mean below 50$ cheap or even way cheaper) and try to upgrade it.

If you want to start writing programs in C for external hardware — it's a different story.

>>	Anonymous Wed Oct 7 05:59:04 2015 No.885149 >>885146 All I want is to write a program and design a circuit that can control a motor or two wirelessly, I'm not looking to build anything of complexity or quality.

>>	Swifty netbook Wed Oct 7 08:18:25 2015 No.885171 >>884862 Right. So the procedure is likely going to be >check 'consumables' >replace >works Y/N >Y, sweet >N, warehouse --> give customer new one assuming warranty

Swifty netbook Wed Oct 7 08:30:28 2015 No.885175

>>885092
Actually, you know what.
Let me fall for it.
Most if not all my posts here are helpful, I can afford some metaposting.
What's wrong with getting acquainted with a job before doing it? Even if I'll only be there for two weeks, that doesn't change the fact that I don't want to slow down the process by having my superiors nurse me for the first day or two. It can be a perfectly simple topic, I know how those machines work, but there's always the little procedural details.
Sure you can bother fixing a completely torched circuit board with fucked bearings and a seized motor, but in some (most) cases I'm told the item simply gets replaced completely, since it's simply not worth it if you translate the man hours of repair time vs production cost of a single tool.

Clearly you have something against me (or just trips in general), but keep in mind, as far as reputation goes. Let me get a worse one, that's the point.
I don't filter my posts (good ones go under my name, bad ones under Anon). That'd just be cheating.

Anonymous Wed Oct 7 11:44:19 2015 No.885214
File: 348 KB, 1205x809, imgp5542_v1.jpg [View same] [iqdb] [saucenao] [google]

Pic related, I just received these Chinese transistors. They have a package which has similar size and shape as an ordinary TO-126, but without the metal tab in the back.

Does anybody know what is the thermal resistance of this kind of package? What kind of currents could I run through it (without fear of frying it) if I attach the transistor into a small piece of aluminium?

Anonymous Wed Oct 7 12:15:43 2015 No.885233

>>885214
BD136 is so small that the transistor chip itself dominates the thermal resistance even in normal TO-126. If you want to play it safe, you can add, say, 3K/W. The package is (probably) TO-126ML.

That said, how much you trust the Chinese? You think there's a BD136 chip inside the unexpected package?

Anonymous Wed Oct 7 14:41:42 2015 No.885284

Does anyone have any good ideas for installing some kind of pickup in my mouth so I can amplify the sound made by clicking my teeth together? I'm thinking some kind of small piezo chip, but I don't know how moisture-resistant those are. I also don't know how to temporarily attach it to my teeth.

Anonymous Wed Oct 7 15:35:33 2015 No.885304

>>885214
those are pulls, you can tell just from the solder wicked up onto the leadframe.

if you're fine with used chips, good, but reemmber the chinks use molten solder pots or blowtorhces, not great for longevity.

Do not buy power tranisistors or mosfets from ebay, alibaba or any chinese source. They WILL be fake. I onyl buy new ones from digikey

>>	Anonymous Wed Oct 7 16:03:53 2015 No.885314 >>885284 can't you have something just outside you mouth?

Anonymous Wed Oct 7 16:33:20 2015 No.885324

>>885284
Google 'contact microphones'. They are dirt cheap, come in packages ready to fix to an instrument or as just the piezo element, and many of them already have a 1/4" plug soldered to them.

Word to the wise though, without a preamp, they won't have great fidelity, but if you are just looking for something to click every time you chomp, they should work fine.

>>	Anonymous Wed Oct 7 17:49:47 2015 No.885359 >>881299 Roll

Anonymous Wed Oct 7 18:57:17 2015 No.885383

>>880229
I need a switched regulated 25A max 6V out 6V>8.5V in power circuit to power my home-made servo board.
I need help to find the cheapest best way to accomplish this.
I am running 17 servos which each have a max current draw of 1.5A, thus my need for 25A peak current for this project.
Please don't quote anything above $20. Unless there really is no choice.

I was thinking of putting together a lot of smaller modules that each do 2 A max at some really nice flexible input and output voltages but maybe if the servos as for too much from one of the regulators it might burn it.

>>	Anonymous Thu Oct 8 15:31:11 2015 No.885647 File: 15 KB, 1088x386, Screenshot_2015-10-08_15-26-42.png [View same] [iqdb] [saucenao] [google] H-hello /diy/. I need to send a low-voltage sample of the mains frequency to a zero-crossing detector. Would this design work?

Anoniemoes Thu Oct 8 17:02:03 2015 No.885686
File: 16 KB, 1452x1018, ir-sensor-illustration.png [View same] [iqdb] [saucenao] [google]

>>883458
I would get a microcontroller with multiple photodiodes, one diode for every position.
For every photodiode there is a corresponding led which lights up in proportion to the amount of IR light the photodiode picks up.
I know for sure this method works very good for short distances, but I'm not sure about 1m+, you might need to put a lot of IR leds all over the place (on the ceiling).
You also might have to make some kind of funnel for the photodiodes, or it might also pick up reflection that's not immediately under the diode.

This is only a matter of aesthetics, but I would also recommend letting the LED's fading in and out for a smoother transition, when someone moves around under the photodiodes.

>>	Anoniemoes Thu Oct 8 17:15:24 2015 No.885694 >>883458 >>885686 Also watch this guy's videos https://www.youtube.com/watch?v=fxkEPKGgv8o

Anonymous Thu Oct 8 18:20:26 2015 No.885719

>>885647
Given that turn ratio, you will end up with exactly 5 volts pk-pk. You might consider using a larger turn ratio just to include a little breathing room, since mains sometimes exceeds 120v rms. If you can afford to exceed 5v pk-pk then this would be ok.

Same thing with your current limiting resistor. It will limit to 100mA, assuming that the voltage never exceeds 5v. Try increasing it to the next standard value (520 ohm? 560 ohm?) just to include some breathing room.

Tldr your circuit is theoretical correct, but in real life it may produce something more than 5vac at 100mA.

>>	Anonymous Thu Oct 8 19:40:45 2015 No.885743 you niggers clearly do not know how much RS232 equipment is still in use, and will be for a long time. Learning to program on an old box might not be so fucking useful, if it's something he'd want to continue doing for a while.

>>	Swifty !tU8/N3szhw Thu Oct 8 19:49:36 2015 No.885747 >>885175

>>	Anonymous Thu Oct 8 19:54:11 2015 No.885749 Im this asshole back again >>881401 What does it mean if a transformer has multiple primary/secondary windings? could I use a 150v/230v primary 14v parallel 28v series transformer ?

Anonymous Thu Oct 8 21:39:18 2015 No.885785

>>885749
It sounds like you're describing a central tapped transformer. These are commonly used for split rail power supplies (ones with -Vcc, GND, and +Vcc). You can ignore the central tap and get 28v out of it, or use the central tap and get 14v out of it. You only want to use the central tap and one of the other outputs (doesn't matter which one). Don't try to connect them, they're opposite polarity.

Anonymous Thu Oct 8 21:44:41 2015 No.885787

>>885719
I guess I'll go with a ratio of 170 V to 3 V peak to peak then. This should allow a pretty huge margin of safety. Also, as it turns out, my current cannot exceed 40 mA, not 100, so the resistor ought to be at least 75 Ω. I'll probably go with 100 or 150. As long as Arduino can still pick up the zero-crossings, it should be fine. Thank you very much for your help.

>>	Anonymous Fri Oct 9 03:03:14 2015 No.885876 >>881299 rolling

Anonymous Fri Oct 9 03:58:56 2015 No.885893

Newbie just getting into electronics here. For my first project I wanted to throw together an audio amplifier using some pre-assembled components.
The main amplifier board I'm looking at requires 22 VAC and the pre-amp board requires 12 VAC. Do I need two separate transformers?
And if so, do I simply wire the primaries in parallel?

Anonymous Fri Oct 9 12:55:50 2015 No.886032
File: 91 KB, 968x640, circuito1.jpg [View same] [iqdb] [saucenao] [google]

Hello /diy/. I'm trying to build the guitar pedal circuitry showed. The site's PDF schematics is the top one. I have two questions, which may be kind of stupid.
1- Is the schematic above the same thing as the below? The lower has the red "wires" that I added so that the circuitry makes more sense to me, as I mounted it that way.
2- I see the grounding part but I don't understand how it is supposed to be grounded. Is it that everything supposed to go ground will be in the same node of the outer part of the jack that will be actually grounded?

Anonymous Fri Oct 9 13:31:21 2015 No.886043
File: 55 KB, 749x499, dmnd8482_png_project-body.jpg [View same] [iqdb] [saucenao] [google]

Speaking of things my wife says, anyone else getting a snickerdoodle? Seems to solve a lot of short comings of other platforms. Like I can't stand the PI, too far above the metal to do anything interesting, too slow to actually be a useful computer. But this seems interesting, while it can run loonix you also have that baller as fuck FPGA to implement stuff on with a usable amount of I/O.

>https://www.crowdsupply.com/krtkl/snickerdoodle

>>	Anonymous Fri Oct 9 13:34:46 2015 No.886044 >>886032 1&2: yes

>>	Anonymous Fri Oct 9 13:42:35 2015 No.886046 >>886043 hi ryan

>>	Anonymous Fri Oct 9 13:45:49 2015 No.886047 File: 106 KB, 1000x668, 1433886082089.jpg [View same] [iqdb] [saucenao] [google] >>886044 thank you based anon. i'll make sure to come back here when i know enough to help other people.

>>	Anonymous Fri Oct 9 13:46:00 2015 No.886048 >>886046 god why does everyone always assume it's ryan, how's a nigga suppose to get anywhere with all this misrepresentation.

>>	Anonymous Fri Oct 9 14:59:25 2015 No.886062 >>881299 Roll

>>	Anonymous Fri Oct 9 17:47:34 2015 No.886117 >>885893 Just get 2 of the power supplies that you can find on amazon. thay have a screw potentiometer on them to pick the target output voltage from like 5v to 24v. you wont have power problems because it is max 15A, which is very large.

>>	Anonymous Fri Oct 9 19:37:40 2015 No.886155 What can I do with a 7400LS IC kit that I just impulse bought from radioshack?

>>	Anonymous Fri Oct 9 19:39:19 2015 No.886156 File: 113 KB, 855x570, 2015-03-27T00_34_51.398Z-0294.jpg.855x570_q85_pad_rcrop[1].jpg [View same] [iqdb] [saucenao] [google] >>881299 rolling also, what can I do with a 7400LS IC kit I just impulse bought from radio shack?

>>	Anonymous Fri Oct 9 20:22:28 2015 No.886166 >>881299 Rollin

Anonymous Fri Oct 9 20:26:17 2015 No.886167
File: 494 KB, 1384x3768, universal_strong_style_color_b82220_car_strong_pcb_control_fully_automatic_power_antenna_strong_style_color_b82220_fender_strong_m[1].jpg [View same] [iqdb] [saucenao] [google]

Hello, radio ignorant fag here.

So I have a 4W TCB-550 CB Transceiver. I also have an automatic car stereo antenna. Transceiver impedance calls for a 50 ohm antenna, the car stereo I assume is 75 ohm and that is not great, but that is as far as my knowledge goes.

If I rig a connection between the two, will I damage my transceiver? Will I be able to receive/transmit at all? I am incredibly poor and can't afford a CB antenna in time for this post apocalyptic scout themed backpack component to be ready as part of my functional Halloween costume. Plus the automatic antenna looks sweet AF, but I want it to be more than moving decoration on this outfit. It doesn't need to work well, it just needs to not fry my transceiver.

Can I get away with it? Wisdom needed.

>>	Anonymous Fri Oct 9 20:37:34 2015 No.886169 >>886167 you'll have trouble picking up signals clearly in noisy environments, you can probably get away with adding a termination resistor at the base of the antenna and winding it up to the correct height, it'll be a piss poor antenna though.

Anonymous Sat Oct 10 03:08:35 2015 No.886285

>>886167
>the car stereo I assume is 75 ohm and that is not great
More importantly, it's 75 ohms at FM band. It's something totally different at CB band.
If the radio isn't shit, it probably won't die, but like the other anon said, it will work pretty badly.

>>	Anonymous Sat Oct 10 06:46:14 2015 No.886323 >>886043 FPGA toolchains are such an enormous fucking pain in the ass, and the free versions have lots of limitations. >>886156 Do you even need to ask? Shove it up your butt.

>>	Anonymous Sat Oct 10 07:51:29 2015 No.886330 >>886167 You would be best ditching that antenna and getting something longer then build an atu to tune it up. Even a broom stick with wire up it and an atu would be better.

>>	Anonymous Sat Oct 10 07:57:50 2015 No.886331 >>886169 Thanks for the info! Decided not to risk it. Local electronics store has a proper CB antenna for cheap so I'm raiding my spare change jar. >>886285 The unit also runs AM and FM as it is a multi band, but yeah, going for a proper antenna so!

>>	Anonymous Sat Oct 10 12:40:17 2015 No.886393 >>881299 roll

>>	Anonymous Sun Oct 11 00:08:48 2015 No.886636 >>886331 >going for a proper antenna Just remember is it is one designed for a car it requires the metal of the car as a ground plane. Mounting it on a back pack is not ideal. >>886331 >AM and FM Is halloween a thing in the uk and europe.

Anonymous Sun Oct 11 01:10:36 2015 No.886665

>turn multimeter to 10A setting
>insert it into circuit connecting led grow light to a 12v 1.4a power brick
>plug in brick
>multimeter reads nothing and the light doesn't turn on
why? the circuit works when i replace the multimeter probes with a jumper so the problem is the meter i assume.

>>	Anonymous Sun Oct 11 01:23:20 2015 No.886667 >>886665 Check the fuse for the 10 amp range. Blowing that is common place.

>>	Anonymous Sun Oct 11 01:36:13 2015 No.886671 >>886667 turns out i was just a retard and hadn't plugged the probe into the 10a jack on the meter

Anonymous Sun Oct 11 05:26:32 2015 No.886720

I have a 24v/5a power supply being run through a PWM (4khz) PMIC which is bringing it down to 13v. When I connect a 12v/1.5a idle motor to the outputs the power supply starts making a loud beep and nothing else happens. Anyone have any idea what's up? The only documentation I can find on the PSU says nothing about beeps.

>>	Anonymous Sun Oct 11 06:14:10 2015 No.886729 >>886665 check the connection of the leads, make sure you have them plugged in correctly. most multi-meters use a different socket for the red lead when using current as apposed to voltage

>>	Anonymous Sun Oct 11 17:12:09 2015 No.886952 How rigid is tinned copper wire? I'm making an LED cube and the scaffolding of the cube needs to be some kind of rigid conductive metal. The best material I've found is 16 gauge tinned copper wire, but it's kind of expensive. Any suggestions?

>>	Anonymous Sun Oct 11 17:26:51 2015 No.886963 >>886952 Overkill, but you can generally get short lengths of romex at the hardware store for cheap than a roll of bus wire will cost ya.

>>	Anonymous Sun Oct 11 17:31:21 2015 No.886965 >>886963 Oh yeah I didn't think about that. Thanks man, I'll run down to the hardware store before they close.

>>	Anonymous Sun Oct 11 17:35:57 2015 No.886968 >>886952 Why not small round stock?

Anonymous Sun Oct 11 17:39:33 2015 No.886970

>>886968
It needs to be somewhat flexible. If it's too rigid it'll be a pain in the ass to solder to my LED leads since they're not all cut the exact some length.

Romex seems like the best bet atm. It won't look as pretty since it probably won't be silver like bus wire so it won't match the LED leads or solder joints but it's definitely the cheaper option.

Anonymous Sun Oct 11 19:12:58 2015 No.887014

>>886636
I know that it won't work as well on the backpack, but that doesn't seem to be much of an issue sadly. I mounted it on the roof on a 1m^2 sheet of 1/16" steel for a test run and various other locations, couldn't get anyone. I live in a medium sized city so I was surprised. 3 years ago I had a crappier antenna and before it broke I would sometimes get the odd trucker, taxi driver and a cool radio enthusiast in Florida now and again. Airwaves are totally dead this weekend, housemate and I had it scanning for hours and the most we picked up were some faint distortions in static consistent with human speech. I think people still use it more in the countryside where mobile coverage is shit, because CB equipment regularly sells in the local shop. It's made me interested in getting into HAM though.

Halloween is a thing out here, just not as big. Get a few trick-or-treaters every year and people head out on the town dressed up for the night. Sometimes there are prizes in pubs etc for the best costume. It's a bit of craic!

>>	Anonymous Sun Oct 11 21:42:10 2015 No.887074 >>885084 no

>>	Anonymous Sun Oct 11 22:52:20 2015 No.887112 >>886952 tinned copper is rigid but inflexible, make sure it doesn't move

>>	Anonymous Sun Oct 11 23:29:44 2015 No.887130 File: 9 KB, 313x256, 1444193810420.gif [View same] [iqdb] [saucenao] [google] >>885084

>>	Anonymous Mon Oct 12 02:51:23 2015 No.887235 >>886963 Update on this. I got the romex and stripped it. Damn it's hard as hell to get the solder to take to the bare copper. I may have to just buy the tinned copper.

>>	Anonymous Mon Oct 12 02:54:38 2015 No.887237 >>887235 Sorry to potentially have led you down a dead end. Have any (electronic) flux handy?

Anonymous Mon Oct 12 03:06:42 2015 No.887242

>>887237
Yeah, I keep getting rosin joints when I use it. I might just not be skilled enough to solder at this weird angle on this material but the thing is looking kinda nasty. The only way I get the solder to stick is by putting some on the tip and letting it drip down over the lead across the bare copper wire.
It looks sloppy, but it's good enough for a prototype.
I'm starting with a 3x3x3 to make sure my logic circuit works then I'm moving to a larger cube. The larger cube I'll use nicer tinned wire for.
Also, the copper wire I got is way too thick. It's 16 AWG and they block out the LEDs haha.
It wasn't expensive though, and I learned something so it's all good.

>>	Anonymous Mon Oct 12 03:21:58 2015 No.887251 >>887235 If it's fresh shiny copper, then your soldering iron is just too weak. Use thinner wire or bigger iron.

Anonymous Mon Oct 12 10:32:01 2015 No.887327

>>887242
How big of a cube are you planning on making?

I'm working on a 6x6x6 rgb one right now, and I just used the legs of LEDs to make the structure of the cube; I didn't really need to add additional wires. The only downside is that the spacing between LEDs ended up kinda small, which makes it a bit hard to see all the way through the cube.

>>	Anonymous Mon Oct 12 11:37:00 2015 No.887352 Hey electrical bros... I got another question. When installing a switch for an 80watt bulb. Is it safe to install the switch on the negative wire? Or is there a good reason why most switches ive seen are on the positive wires?

>>	Anonymous Mon Oct 12 11:46:36 2015 No.887356 >>881299 buns

Swifts !WiNDUPyWhk Mon Oct 12 12:10:14 2015 No.887362

>>887352
It's fairly simple really.

The reason why you route the phase wire through the switch is so you can interrupt it, if you need to change the bulb.

The switch works either way, but if you need to change the bulb and the work was done properly, the only live wire you'll be touching is neutral, which won't do anything.

If the job was shitty and the electrician routed the neutral wire through the switch you'll still have the phase lead on the bulb.
Which can kill you, even if the switch is in the OFF position.

Anonymous Mon Oct 12 15:15:50 2015 No.887424

Being a dumbass I managed to blow the mA/uA fuse on my multimeter. Replacements are available, but they are rated at lower V than the original. Does it make much difference if I go for a 500V fuse instead of a 1000V and if so then why?

If it matters at all the multimeter is an Amprobe-520 and it came with a 0.5A/1000V fast fuse...

(I have a hunch that since I'm not going anywhere near anything over 220V any time soon I should be OK with the 500V rated fuse)

Anonymous Mon Oct 12 15:27:30 2015 No.887430

>>887327
My first one is probably going to be a 5x5x5 RGB. The spacing between the LEDs is why I'm trying to use scaffolding. I ordered some bus wire from amazon and it'll be here next week. I'll keep the thread updated once I actually make it.

I want it to look nice too, I plan on giving it to my sister for Christmas assuming I can finish it on time.

Anonymous Mon Oct 12 15:32:14 2015 No.887431

>>887424
It'll blow before you reach the capacity of the meter, other than that, no.

Your hunch is pretty correct. If you're just dicking with household level stuff, you should be good and the worse that'll happen is you'll blow a fuse.

Going down in fuse size is only a concern when you have components that rely on stronger currents than the fuse can handle, but then the juice running through that line would be over the fuses capacity anyway, so it'd just immediately blow.

Going up in fuse size is where you really have to worry about fires/shit blowing up.

There's other shit to consider too, but in this particular application, you're good.

>>	Anonymous Mon Oct 12 15:43:25 2015 No.887435 >>887431 Thanks for the reassuring words. And yes, 99% of the time I'm just fiddling around with a /diy/ PSU and tiny hobby circuitry, staying well between +/-12V.

Anonymous Mon Oct 12 15:47:04 2015 No.887438

Im USAfag trying to order junk from china-land....

1. somebody here mentioned that they had double-height male pin headers,,, so that when you soldered them into a PCB, it ended up with male pins on both sides. do these have a special secret code name? I can find them on google but can't find them at all on aliexpress

2. do the female stacking pin headers come in 40-pin lengths? {single-row, that is} all I have been able to find is the 3x2-row, 6, 8 and 10-pin long versions sold for the Arduino Uno. (also I found that there is a double-row version, mebbe 16x2 pins, for doing something with the rasberry pis,,, but I don't want them)

Sometimes I have to do odd breakouts on boards that are already stacked, and it helps to have a bunch of oddball connector stuff like this to abuse...

Anonymous Mon Oct 12 15:48:12 2015 No.887439

>>887431
>It'll blow before you reach the capacity of the meter, other than that, no.
No, you fucking moron.
It means the exact opposite: the fuse is not guaranteed to blow properly when the voltage is too high. In other words, the fuse arc won't extinguish and anon's meter blows up on his face.

Anonymous Mon Oct 12 16:10:14 2015 No.887444
File: 203 KB, 1080x780, TP4056-1A-Battery-Charger-Module-2.jpg [View same] [iqdb] [saucenao] [google]

more 18650 lithium polymer

multicell 18650 chargers are heinously expensive, so i bought a shitton of t4056 single cell charging boards

i was going to wire these boards in parallel to a high current dc to dc converter, but i read an old stack exchange that says these tp4056 boards need separate dc to dc converters to power them, but no one explains why and it makes no sense

does anyone know why?

URGENT please help Mon Oct 12 16:27:36 2015 No.887448
File: 884 KB, 818x543, Screenshot_2015-10-12_16-27-17.png [View same] [iqdb] [saucenao] [google]

I ended up building the transformer shown in >>885647, except without any load connected to the primary and with a slightly different winding ratio (50:3). It was basically the primary connected directly to a household power outlet via a power cord. On the secondary, I put a 240 ohm resistor rated at 10 W, and a multimeter in parallel with that resistor to observe the voltage.

Contrary to my expectations, one part of the primary winding which was connected to the power cord exploded the instant I plugged it in, and sent molten copper in all directions. The device is now unplugged from the mains, but I am uncertain as to whether the iron core might be carrying a dangerous magnetic field which could collapse rapidly if I shorted the primary. I cannot begin dismantling it because I'm afraid to touch it.

Based on what I explained, is it safe to handle as long as it remains unplugged? If not, how would I render it safe?

>>	Anonymous Mon Oct 12 16:36:31 2015 No.887450 File: 3.54 MB, 4160x2340, 20151005_203726.jpg [View same] [iqdb] [saucenao] [google] >>887430 Cool, would like to see it when its finished. What are you going to be using to drive the LEDs?

Anonymous Mon Oct 12 17:23:27 2015 No.887456

>>887448
>Contrary to my expectations, one part of the primary winding which was connected to the power cord exploded the instant I plugged it in, and sent molten copper in all directions.

...exactly what the fuck were you expecting, then?

>but I am uncertain as to whether the iron core might be carrying a dangerous magnetic field which could collapse rapidly if I shorted the primary.

Inductors do not work this way. Take the thing apart, and, for fuck's sake, learn more (like a lot more) about electronics before you go dicking with mains power and kill yourself or someone else.

>>	Anonymous Mon Oct 12 17:27:49 2015 No.887458 >>887456 >exactly what the fuck were you expecting, then? I thought the resistor on the secondary would put a hard limit on the amount of current the entire device would draw from the mains. >Take the thing apart >learn more Will do. Thank you.

Anonymous Mon Oct 12 18:39:39 2015 No.887478

>>887458
>I thought the resistor on the secondary would put a hard limit on the amount of current the entire device would draw from the mains.

It would, sort of, but only as long as there's enough inductive coupling between the primary and secondary, which there was _no way_ you had with that setup.

Anonymous Mon Oct 12 18:55:42 2015 No.887487

>>887478
That core is basically salvaged from a squirrel cage motor from a fan. I was a bit hesitant about using it due to its shape, but I figured all the slots and bumps on the inner ring would average out each other's magnetic effect, making the entire core act as a de facto toroid. But in practice, the thing was a pain to wind, the sharp edges probably risk wearing down the wires' enamel, and it's clear there's just not enough space on this thing to do this properly. I tried anyway expecting basically nothing to happen, i.e. no reading on my voltmeter, or at least a very small one.

Anonymous Mon Oct 12 19:55:21 2015 No.887505
File: 15 KB, 557x215, capinfopict9.jpg [View same] [iqdb] [saucenao] [google]

preface: im an retard.
on an axial capacitor the plastic side is positive and the metal side is negative... does it mean i attach the leads negative to positive then positive to negative (opposites) or pos to pos and neg to neg (sames)?

also if i wanted to use a small capacitor bundle to smooth and buffer a charge going to a battery (from the charging coil of a small engine) should i put them in front of the positive or negative?

Anonymous Mon Oct 12 20:00:48 2015 No.887508

>>887505
by capacitor bundle i mean a group of 3 identical 35v 4700uf caps in parallel i had lying around which should be more than enough for the ~12v 25w coil (measures 18-22v without a battery, however i think thats just because it doesnt have a load)

>>	Anonymous Mon Oct 12 21:31:37 2015 No.887535 >>887508 Negative goes to negative and positive to positive. Also, you can put those 3 caps in parallel and it will do what you want it to, just make sure that, if they're rated for 35 volts, they never see more than 28 volts or so.

Anonymous Tue Oct 13 03:12:02 2015 No.887599

>>887487
>I tried anyway expecting basically nothing to happen
You had few turns of relatively thick wire on a tiny core. It was practically a short circuit. Typical small transformers have couple of thousand turns of wire.
It is certainly possible to /diy/ transformers and it isn't even difficult, but please refrain from doing so until you understand transformers and electrical safety bit better.

>>887535
There are electrolytic capacitors capable of handling several hundred volts. They're common in power supplies and CFL/LED ballasts.

>>887505
Sounds like it would be a good idea to draw a pic of what you are thinking.

>>	Anonymous Tue Oct 13 04:13:27 2015 No.887606 >>887130 >>887074 Ok thank you. but I figured out how to fade 12 leds using the softPWM library. Just had to modify the code a bit. thanks anyway!

Anonymous Tue Oct 13 06:54:27 2015 No.887630

>>887444
I have one of these, but I would suspect because of switch mode problems.

Like, having two paralleled SMPS is a bad idea, having more loads of one DC-to-DC converter would be a problem.

Dunno. Don't listen to what people say, try and see for yourself.....maybe it works, maybe it doesn't. You'll soon figure it out. #yolo

Anonymous Tue Oct 13 13:48:28 2015 No.887719

>>880229
Hey guys south carolina fag here and my (beautiful, incredible sounding) old tube amp was submerged during the recent flooding. I did not find out until days later (much to my ire). I realize I will likely have to rebuild it but what are the chances the transformers (I have extras but I wanted to use those for a new build of a hombrew idea I have) are still good? The fiberboard is curved like a sine wave.

Anonymous Tue Oct 13 15:21:49 2015 No.887741

>>883458
I would consider using a sonar sensor like an HC-SR04 unit or something similar then after a certain threshold of closeness i'd just scale the return time to PWM value of the led(s). An arduino clone one of these ssesnor and a transistor would make this super easy.

>>	Anonymous Tue Oct 13 17:03:51 2015 No.887781 >>881299 roll

Anonymous Tue Oct 13 17:46:10 2015 No.887808

>>887719
Fortunately, most of the electronics would be able to survive being submerged, assuming the power wasn't on and won't be turned on for a while.

The real problem is that the circuit board soaked up a bunch of water and will never be the same. If you ever try to flatten it out, you will end up breaking the copper traces.

Bottom line, in my opinion, is that most, if not all of the actual components are salvageable, but you would need a bate board that is wired correctly to reconnect them. In all honesty, you might just try drying the whole thing out, replacing the speaker, and plugging it in to see if it still works. If it's still hot enough in SC, try leaving it in a car, with the windows rolled up, in the sunlight, for atleast a week. You may also put a couple of containers of damp rid in there to help collect water. Just be careful when you plug it in for the first time (use a power strip with a switch on it and stand well away when you do it) and hope that drying it doesn't crack the traces on the pcb.

Anonymous Tue Oct 13 23:08:29 2015 No.887916

>>887808
It is actually point to point and I was intending on rebuilding that anyway. I feel like the pots might have gotten mineral deposits in them and would be unfit for use, but I will not know until I hear it, I suppose. I am gonna hose it down with some WD40 to get the water that might be lingering about and hit all the tube sockets with contact cleaner and then I suppose I will hook it up to a load and plug it in just to see.

It would really suck to lose the transformers is all as they are the most expensive individual components. And I am afraid some short may have happened internally in one or more of them and I will fry one if I hook it up.

Thank you for the response, anon.

>>	Anonymous Tue Oct 13 23:09:30 2015 No.887918 >>887916 >rebuilding that By which I mean the main circuit board, which is fiber eyelet board.

>>	Anonymous Tue Oct 13 23:20:52 2015 No.887921 >>887352 There's no such thing as a 'negative' or 'positive' wire for AC.

>>	Anonymous Wed Oct 14 00:14:57 2015 No.887946 File: 24 KB, 1024x512, Untitled.png [View same] [iqdb] [saucenao] [google] >>887599 pic was from google, not representative of what i have pic related my thought

Anonymous Wed Oct 14 00:33:01 2015 No.887950

>>887946
You've put the capacitor in series between the power supply and battery. You should have put it in parallel with the battery and charger.

Current doesn't flow through a capacitor. You get decoupling (smoothing) by putting it in parallel with a noisy source.

>>	Anonymous Wed Oct 14 00:33:09 2015 No.887951 If you wired 1000 potato batteries together, could you make an arc welder with it?

>>	Anonymous Wed Oct 14 01:04:09 2015 No.887959 File: 17 KB, 1024x512, 1444796097891.png [View same] [iqdb] [saucenao] [google] >>887946 you mean like this, or?

>>	Anonymous Wed Oct 14 01:06:26 2015 No.887960 >>887951 sure, if it put out like 100+ amps. considering a tater makes like 2 milliamps or some shit, youre gonna need a LOT of potatoes

>>	Anonymous Wed Oct 14 01:30:28 2015 No.887962 >>881299 roll

>>	Anonymous Wed Oct 14 02:56:40 2015 No.887978 >>887959 Yes.

Anonymous Wed Oct 14 05:03:58 2015 No.887992

Not sure if this is the right place to ask, but I want to make a USB-3.0 powered external monitor out of the LCD panels from old, dead laptops. What is the process of implementing this setup?
My research so far makes me realize that I need a power supply for the monitor, a control board for the monitor, and I can logically conclude that the USB 3.0 plug will somehow actually interface with both of these. What goes in between?

Anonymous Wed Oct 14 14:44:26 2015 No.888130
File: 132 KB, 1306x678, mosfucked_h3984rhq394h.jpg [View same] [iqdb] [saucenao] [google]

funny story time:
some weeks ago I splurged and bought a bunch of these little mosfet boards off aliexpress for $1 each (they are the same as this pic, marked Keyes", "MOS Module" and "140C07")

went to hook it up to switch a 5mw laser on and off, and it dint werk,,,
check power lines to mosfet board:good
check arduino vcc, gnd, signal pin: good
check wires to laser: good
check connect laser directly to 3.3v line on the power supply == laser works perfectly fine
check voltage coming off the V+ and V- of the mosfet board == 3.3v, just as it should be
laser still dont werk connected to mosfet outputs

,,,,repeat above a couple times,,,,,

so I start hunting for clues online, and it turns out that the mosfet they put on these boards is not an "L" series--it needs 10 volts to switch on totally.... even tho they say it's for "arduino rasberry pi", that would only put out 5v or 3.3v..... so you don't get hardly any current through the thing as it is. :|

I have no idea why they do this??? it don't work as it is.
A lot of these little modules have IRF520 or IRF540 mosfets, and neither of them is going to work correctly on 5v... ???

I took off the IRF520 mosfet and put on a IRLZ34 instead.... it works perfect on a 5v arduino now, but I got those mosfets somewhere else

>>	Anonymous Wed Oct 14 16:24:12 2015 No.888180 >>888130 >mosfet >aliexpress You got what you deserved.

>>	Anonymous Wed Oct 14 18:20:37 2015 No.888251 >>888130 The funny part of this is that you were using an Arduino.

Anonymous Thu Oct 15 00:58:37 2015 No.888389
File: 11 KB, 299x169, 1304808013050.jpg [View same] [iqdb] [saucenao] [google]

>>888180
>You got what you deserved.
the sad thing is, it's still worth it...
other places want $6-$7 each for similar boards with a logic-level mosfet already on it.
so you can buy these and toss the IRL520, put a IRLZ34N on there (that costs ~55 cents on aliexpress) and still be ahead

>>888251
>The funny part of this is that you were using an Arduino.
they're cheap, easy to use and they work for what I need... there is no reason to use anything else. function not fashion m'laddy

>>	Anonymous Thu Oct 15 01:26:31 2015 No.888404 >>881299 ayyy

>>	Anonymous Thu Oct 15 01:30:33 2015 No.888405 >>888389 Swapping one fake transistor for another sounds like a great plan.

Anonymous Thu Oct 15 02:12:58 2015 No.888419

>>885149
Yes but connecting all that stuff to your computer will be harder, is what is implied by such venture.

Because you are a beginner you probably want to just copy paste already existing code and do light soldering and connections. Even at this level, you will mess up and learn a ton (enough to get you to the next level).

To connect your computer wirelessly to a motor that is not wired to the computer, do this:
(computer > USB > arduino1 > NRF24l01) >>>wireless connection here >>> (NRF24l01 > arduino2 > motors)

From playing with arduino you'll get shit done. Eventually you'll understand the arduino library were written with slow code so that you can move on and rewrite the code to really learn the ins and outs of this stuff (if you want, otherwise the arduino library work enough).

>>	Anonymous Thu Oct 15 02:48:03 2015 No.888427 >>888405 >Swapping one fake transistor for another sounds like a great plan. so then, all of the electronics components sold from China are fake?

>>	Anonymous Thu Oct 15 02:58:09 2015 No.888428 >>888427 Better question: how much time and money you're willing to spend on debugging problems caused by fakes? Are you even skilled enough to realize your stuff does not work because component marked A is actually B?

Anonymous Thu Oct 15 08:14:31 2015 No.888493
File: 58 KB, 400x434, computer_f93dh5j7.jpg [View same] [iqdb] [saucenao] [google]

>>888428
>everything might be fake
But both components did work... The original was just a less-than-ideal choice in this instance.

Anyway--most China fakes and salvage is VLSI chips that are expensive to buy new. I've bought lots of basic components off aliexpress and not had issues with any them not working as intended. Many of these retail for only a few cents each. The IRF520 and IRLZ34 mosfets both only sell for about fifty cents.

Higher up the price scale, so far all the couple dozen arduino copies I've bought worked 100%.... All the TFT screens I've bought worked 100%.... A bunch of stepper and BLDC motor drivers and rotary encoders all worked 100%...

What kinds of fakes do you suspect exist?
I have heard of two in particular:
1--the Sparkfun arduino chip fakes, that were totally non-functional ( I test the boards when I get them, I load a different 'blink' sketch and see if they run it properly )
2--the FTDI chip fakes,,,, but I never saw any message on the PC that any of the arduino boards I had did anything wrong. And the FTDI thing was relatively huge.......

From my perspective the danger of buying incorrect parts seems to be larger than the danger of buying counterfeit parts. How much should I worry about having a problem that I don't have?

Anonymous Thu Oct 15 12:45:15 2015 No.888553

>>888427
There's a lot of them, and buying from places like Alibaba you run a higher risk of getting some.

>>888493
>Anyway--most China fakes and salvage is VLSI chips that are expensive to buy new.
A lot of it (esp. opamps, transistors and similar) is re-marking parts that may be sorta kinda similar. If you're lucky they may even work on a superficial level. Sometimes they're even domestically produced components that could be perfectly good in their own right, but then they're packaged and marked as something they're not.

http://zeptobars.ru/en/read/Nordic-NRF24L01P-SI24R1-real-fake-copy
http://zeptobars.ru/en/read/OPA627-AD744-real-vs-fake-china-ebay
http://zeptobars.ru/en/read/FTDI-FT232RL-real-vs-fake-supereal

>>	Anonymous Thu Oct 15 13:31:26 2015 No.888559 >>888553 We also have an example in this very thread. There's a pretty good chance that >>885214's transistors aren't what they're supposed to be.

>>	Swifts !WiNDUPyWhk Fri Oct 16 11:47:43 2015 No.889035 File: 1.38 MB, 2592x1456, WP_20151016_17_43_59_Pro.jpg [View same] [iqdb] [saucenao] [google] >school throwing out old gear Scored a neat Sine wave generator

>>	Anonymous Fri Oct 16 19:27:15 2015 No.889212 >>881299 roll

>>	Anonymous Fri Oct 16 20:10:24 2015 No.889231 >>881299 rollan

>>	Anonymous Fri Oct 16 20:11:29 2015 No.889232 >>889231 wtf is a ticking bomb? A device that just makes ticking noises?

>>	Anonymous Sat Oct 17 03:55:27 2015 No.889371 >>889232 Nah anon, it's just a clock. :^)

>>	Anonymous Sat Oct 17 04:34:13 2015 No.889377 File: 283 KB, 1000x388, ss (2015-10-17 at 01.31.26).png [View same] [iqdb] [saucenao] [google] is this a good purchase for wanting to get into arduino?

>>	Swifts !WiNDUPyWhk Sat Oct 17 04:37:47 2015 No.889378 >>889377 No. The kits are a fucking scam. Don't know specifically about this one, but the big $85 dollar one on Adafruit is just a straight up scam. If you were to buy the components seperately you'd end up saving atleast $30.

Anonymous Sat Oct 17 04:41:03 2015 No.889380
File: 182 KB, 1366x768, ss (2015-10-17 at 01.39.36).png [View same] [iqdb] [saucenao] [google]

>>889378

That's what I feared. I have a storefront in a tab and I've been putting things in my cart that are in the projects in pic related but it's just exhausting. I pretty much wanna tap out and do the easy way.

I guess I'll go back to doing that.

Anonymous Sat Oct 17 05:26:22 2015 No.889390

>>889377

given the exchange rate, and all the stuff you're getting, $60 CND is a very reasonable price.

here is a $95 kit from a canadian source which has considerably more nice stuff, like a servo and a voice sensor: https://abra-electronics.com/educational-kits/arduino-educational-kits/ard-ultimate-ultimate-learning-kit-for-arduino.html?currency=CAN

>>	Anonymous Sat Oct 17 05:28:41 2015 No.889392 File: 306 KB, 1012x371, ss (2015-10-17 at 02.27.45).png [View same] [iqdb] [saucenao] [google] >>889390 Already ahead of you, m8. This kit is also 50CAD on aliexpress but I'm not sure about waiting 1-2 months.

Anonymous Sat Oct 17 08:40:01 2015 No.889418
File: 9 KB, 800x491, Untitled.png [View same] [iqdb] [saucenao] [google]

I have a weird problem. I'm trying to run a reversible 24v motor off a PMIC, which is just an H Bridge as far as I can tell. It's wired as shown in pic, really simple.

For some reason when I measure the voltage across the PMIC when it's activated without the motor connected, I get 24v as expected. However, when I connect the motor it only reads 2v and the motor turns extremely slowly. Does anyone have any idea why? I don't have an ammeter but the motor claims to use 1.5a idle and the supply and PMIC are both 5a rated so I don't think current is an issue. Please help I don't know anything about electricity.

PMIC sheet: http://www.infineon.com/dgdl/Infineon-TLE5206_2-DS-v01_01-en.pdf?folderId=db3a30431b3e89eb011bb632994f065b&fileId=db3a30431f848401011fc753a71779a7&ack=t

>>	Anonymous Sat Oct 17 10:27:06 2015 No.889463 >>889418 do a proper drawing, and mark all the voltages present. we cant diagnose anything without numbers. often, the very act of simply documenting the voltages will lead one to find the fault.

>>	Anonymous Sat Oct 17 10:52:08 2015 No.889468 >>889418 the thing has an error flag and everything? check the table at the end, play with the inputs, try and match the detectable/undetectable error flag outputs and see what matches. does the motor work directly on the supply?

>>	Anonymous Sat Oct 17 12:04:23 2015 No.889493 File: 1.09 MB, 2592x1944, IMG_20151017_090231496.jpg [View same] [iqdb] [saucenao] [google] >>880840 18650bro reporting in >120 cells processed this week

>>	Anonymous Sat Oct 17 14:41:12 2015 No.889552 >>889468 Yeah the error pin is low which matches an error for the undervoltage case. The motor runs great (tested under load too) directly off the 24v supply with either polarity. Sorry for the late reply.

>>	Anonymous Sat Oct 17 15:00:42 2015 No.889558 >>889552 I don't really trust your diagnosis, but assuming it's correct: your PSU is shit or your driver's bypass capacitors are inadequate.

Anonymous Sat Oct 17 15:12:39 2015 No.889561
File: 63 KB, 800x600, 090424095444652493539213.jpg [View same] [iqdb] [saucenao] [google]

Got that old baby still working.
problems:
+ the sound is a bit dirty on higher levels of the incoming signal.
+ it makes white noise when sliding the volume up & down
Is it an easy process ? At which components should I give my focus to find the problem ? Does this require an Oscilloscope or is it doable with just a multimeter ?

>>	Anonymous Sat Oct 17 15:15:27 2015 No.889562 >>889552 how is the uc powered? you connected all the 0v together right? pmic needs 3 wires going to uC

>>	Anonymous Sat Oct 17 15:21:04 2015 No.889564 >>889562 uc is connected to desktop usb but I measured the voltage from uc output high to psu ground and got 6.5v which is within the pmic's input range. The third data pin is the error flag which I'm just reading with a voltmeter.

>>	Anonymous Sat Oct 17 15:23:14 2015 No.889566 >>889561 The latter problem can be fixed by cleaning the volume pot. There are sprays for that purpose, but you can also open it and clean it manually. No idea what you mean with the first one.

>>	Anonymous Sat Oct 17 15:25:14 2015 No.889567 >>889564 > from uc output high to psu ground and got 6.5v ... Which gets us back to >>889463's request, as it's rather unlikely your controller runs at 6.5V.

>>	Anonymous Sat Oct 17 15:49:35 2015 No.889571 File: 92 KB, 1885x1568, Untitled.png [View same] [iqdb] [saucenao] [google] >>889567 Alright I made something more detailed. I don't know what constitutes a proper drawing for a circuit so if this isn't what you're after just say so.

>>	Anonymous Sat Oct 17 16:07:51 2015 No.889577 >>889571 the 5V / 6.5V disparity should not exist, coz the uC gnd has to be tied to the PS gnd. otherwise, the 2 input signals have no reference to anything.

Anonymous Sat Oct 17 16:08:57 2015 No.889579

>>889571
One which includes all the components and how they're connected. How do you expect us to spot errors in your circuit if you don't show it to us? On the other hand, it doesn't need to be pretty, shitty doodle on paper suffices.

See >>889562; you need to connect Arduino's ground to PSU/PMIC ground for it to work.
Also, bypass capacitors near PMIC might be required.

Anonymous Sat Oct 17 16:14:03 2015 No.889582

>>889577
>>889579
You guys are focusing on the uC's ground but I should make it clear that the PMIC still toggles on and off fine suggesting that the input is working. Do you think it's the cause of the problem anyway? At any rate that is the whole circuit. Not sure what extra detail I can add.

With regard to the bypass caps is there anywhere I can read up on those in the context of motor control? Googling them suggests that they're a pretty broadly applied thing.

>>	Anonymous Sat Oct 17 16:15:49 2015 No.889583 >>889582 >Do you think it's the cause of the problem anyway? we are 100% certain. put the grounds together! you made a silly noob mistake.

>>	Anonymous Sat Oct 17 16:19:25 2015 No.889586 >>889583 Alright, thanks for the help. I can't run the uC off the psu right now because I don't have anything to sink the heat a 5v regulator would put out, but I'll give it a shot next time I'm on campus.

>>	Anonymous Sat Oct 17 16:19:40 2015 No.889587 >>889582 >PMIC still toggles on and off fine funny things happen when you don't have any loads connected.

Anonymous Sat Oct 17 16:27:09 2015 No.889589

>>889582
>With regard to the bypass caps is there anywhere I can read up on those in the context of motor control?
The datasheet of your IC would be the first thing to read. It has example schematics.

>>889586
You don't need to power your Arduino from that 24V supply. You need to connect the grounds together. One pin. Together with your two control pins, three pins.

>>	Anonymous Sat Oct 17 17:02:16 2015 No.889601 File: 906 KB, 1920x1080, 2015-10-17 16.56.43.jpg [View same] [iqdb] [saucenao] [google] >>889589 >>889587 >>889583 Based /ohm/. Enjoy a picture of my expert wiring skills.

>>	Anonymous Sat Oct 17 17:14:20 2015 No.889604 >>889601 >Based /ohm/. so does it fucking work or not also i'm embarrassed that i simultaneously couldn't work out what those grips were up to or find the motor driver. what are the black wires doing? long jumper?

>>	Anonymous Sat Oct 17 17:16:31 2015 No.889606 >>889604 Yeah it works well. The black wires are for a 12v power brick. The arduino has an onboard regulator that'll do up to 12.

>>	Anonymous Sat Oct 17 17:17:45 2015 No.889607 >>889606 GJ. what is it for?

>>	Anonymous Sat Oct 17 17:21:33 2015 No.889609 >>889607 It's controlling a set of trim tabs, which are basically stabilizers for boats if you're not familiar with them.

>>	Anonymous Sat Oct 17 18:04:06 2015 No.889622 >>881299 fuck it

Anonymous Sat Oct 17 18:48:20 2015 No.889640

I'm building a fairly ghetto rail gun which involves discharging a 300 volt 10000uF capacitor through the two rails, basically a short circuit that generates some electromagnetic propulsion. My problem is that I really don't think that the wires I'm using to connect the capacitor to the rails are big enough, they're only 18 gauge. The two main problems are that I don't know whether the wires will fry, and whether the wires will have too high an impedance to function. The reason the wires are so thin is because I didn't know whether any kind of corrosion would occur if I used copper wires instead. It seems obvious that the wires that small would fry, but since the power is very momentary, I wasn't too sure. Anyone got any pointers?

>>	Anonymous Sat Oct 17 20:01:57 2015 No.889671 >>889640 It's a piddly amount of energy anyway, you're not going to get much.

Anonymous Sun Oct 18 01:39:20 2015 No.889778

>>889640
I built a coil gun, so not exactly the same, but... basically I wound the coils with enamel coated 18AWG wire, and the power supply will switch them on for less than a second each. The power supply is 170VDC, and I estimate it's providing around 30A. After 5 or 6 shots, the coils start to warm up. After 12 to 20 shots they are hot. Again, these would just be estimates for you, but I hope it helps. In my opinion, I would be as interested in the insulation as the gauge. I would recommend considering romex as an alternative to what you're using now.

Anonymous Sun Oct 18 13:05:58 2015 No.889949

>>889640
Parallel a few wires up until it becomes unpractical, also keep the overall length of the high current path as short as possible.

300v @ 10,000uF is only 450 joules, which sounds like a lot but its really not. Only a fraction of that goes toward moving the projectile.

>>	Anonymous Sun Oct 18 13:12:39 2015 No.889952 File: 85 KB, 960x539, decker.jpg [View same] [iqdb] [saucenao] [google] Does /diy/ like double decker PCBs?

>>	Anonymous Sun Oct 18 13:14:15 2015 No.889954 File: 79 KB, 960x539, decker 2.jpg [View same] [iqdb] [saucenao] [google]

>>	Anonymous Sun Oct 18 13:16:10 2015 No.889955 File: 82 KB, 960x539, decker 3.jpg [View same] [iqdb] [saucenao] [google] Guess what this contraption does, /diy/ ?

>>	Anonymous Sun Oct 18 13:17:27 2015 No.889956 File: 84 KB, 960x539, control panel.jpg [View same] [iqdb] [saucenao] [google]

>>	Anonymous Sun Oct 18 13:18:27 2015 No.889957 >>889952 Like? No, but they're often necessary.

Anonymous Sun Oct 18 13:30:48 2015 No.889968

>>889957
I didn't like single sided boards, but it turns out soldering wires from one side to the other is a major pain in the anus and copper plating the holes requires conductive ink, which I can't find at all.

I like the look if my double-decker. There is no risk of touching the triacs, since they're on the board below.

Anonymous Sun Oct 18 21:47:39 2015 No.890131

i have a kart engine i recently installed charging coils on for the battery. it outputs like 8-48vdc @1.5-3a depending on rpm with no battery, just my multimeter. however when hooked to a battery my multimeter reads like 12.5-12.75v (battery is about 12.5v by itself). there are no regulators other than a fuse. is this going to detonate my battery and i should get a power converter or am i ok?

>>	Anonymous Sun Oct 18 21:57:37 2015 No.890137 File: 1.79 MB, 3552x2000, WP_20151018_20_54_52_Pro.jpg [View same] [iqdb] [saucenao] [google] >>889952 only did this one because I needed to make better connections to a chip and didn't want to wait for amazon to ship my sockets

Anonymous Mon Oct 19 03:18:51 2015 No.890245

>>889968
>requires conductive ink, which I can't find at all.
You can try car spare parts stores, it is used to fix window heater elements.
It's also a pain in the ass, just like all the other methods for making plated-through holes.

I tried several methods, but the result is that I now mostly order my PCBs, if I need plated holes. And if I absolutely have to make a 2-sided board where the top layer is not all ground, I use thick copper wire which barely fits to the hole and kinda-sorta rivet it to place. It's slightly less annoying that way.

>>	Anonymous Mon Oct 19 06:44:13 2015 No.890280 >>889561 >tfw i bought one for almost nothing and butchered it without knowing what they are worth. I've let my country down.

>>	Anonymous Mon Oct 19 06:45:41 2015 No.890281 >>889601 >vicegrip heatsink boss

>>	Anonymous Mon Oct 19 07:29:51 2015 No.890286 File: 33 KB, 1018x352, my face my soul skeleton.jpg [View same] [iqdb] [saucenao] [google] >>889035 >Iskra Ah fuck. Back in the day Yugoslavia actually manufactured something of value.

>>	Anonymous Mon Oct 19 11:44:04 2015 No.890336 >>890137 That's pretty ghetto

>>	Anonymous Mon Oct 19 11:45:47 2015 No.890337 >>890245 They only sell really small amounts of it. It's just carbon and a resin, why does it have to be expensive?

>>	Anonymous Mon Oct 19 23:05:54 2015 No.890701 >>881299 rollan

Anonymous Tue Oct 20 03:09:23 2015 No.890770

>>890337
The stuff I've seen contains silver. That explains something, but the main reason is that you don't need a huge bottle for fixing a heater element and there's no reason (from the seller's point of view) to sell it at super low price or in big quantities.
Actual graphite based stuff is cheaper and is usually sold in bigger bottles. Check ebay for Aquadag or something. You can expect you need to electroplate copper over Aquadag for it to work for vias, though.
Then there is special stuff for via filling (for plugged vias), containing silvered copper particles. DuPont is one well-known manufacturer, but that stuff is somewhat difficult to find.

Anonymous Tue Oct 20 08:09:54 2015 No.890833
File: 8 KB, 675x533, dumbcuck.png [View same] [iqdb] [saucenao] [google]

Hello retard here

Can someone explain how this configuration ensures constant voltage on R2 (R2 can change it's value)

The guy I got this from said that the Zener diode will do some magic and draw current away from the R2 if R2 value falls

Anonymous Tue Oct 20 10:58:04 2015 No.890866

I have a motion activated camera whose IR lights are too dim to light up my back yard and I'm trying to see what's leaving piles of shit out there. Anyone have source on simple electric circuit to sense voltage on a LED and use it to turn on and off a bigger light source?

Anonymous Tue Oct 20 11:05:35 2015 No.890872

>>890833
http://www.learningaboutelectronics.com/Articles/Zener-diode-IV-characteristics-curve

zener diodes are reverse biased compared to other diodes, and maintain a nearly constant voltage drop across themselves under certain circumstances

because the zener and resistor are parallel they have the same voltage drop, I don't remember how to explain this because it's just something I remember from classes, I've long forgotten the reasoning behind it, probably kirchoff or some shit

>>	Anonymous Tue Oct 20 11:10:17 2015 No.890873 >>889955 Violates wiretap laws?

>>	Anonymous Tue Oct 20 15:31:25 2015 No.890962 File: 18 KB, 500x255, rab-stl360h-stealth-360-deg-with-bell-floods-motion-sensor-lights-27.gif [View same] [iqdb] [saucenao] [google] >>890866 use a motion-activated lamp. about $15 at hardware store, $3 at thrift store.

>>	Anonymous Tue Oct 20 17:58:27 2015 No.891020 >>890962 I'd still have to replace these bulbs with IR LEDs. I'd like to use what I have.

>>	Anonymous Wed Oct 21 03:38:53 2015 No.891193 >>889035 >tfw school "throws away" old tech >"throws away" is just sending it to the nearby recycling shop be sold. Fuck me

Anonymous Wed Oct 21 05:17:07 2015 No.891213
File: 28 KB, 681x564, UVLED.png [View same] [iqdb] [saucenao] [google]

Hello guys, can I ask you a question?
In advance, let me tell you that I have no idea about electronic engineering, but Im and chemical engineer and we are currently working on some doodad that should use UV LED diodes. Can you help me?

Basically we need to several of pic related connected to a power source.
What is the best way to do that? in series or in paralel?
We have a power source that has:
Variable output voltage: 1-16 VDC
Variable output current: 0-60 A

I know Im asking elementary school stuff but still, its better to ask than to destroy a several parts that cost 350 € each.

Anonymous Wed Oct 21 06:05:52 2015 No.891226
File: 18 KB, 467x348, LED IV-graph.gif [View same] [iqdb] [saucenao] [google]

>>891213

the major thing to understand about LEDs is that the have a very sharp I-V curve: as you increase the voltage beyond a certain point, the current line shoots almost straight up into self-destruct territory. so, you always wanna regulate the current rather than the voltage, coz each device has a different inflection point.

so you have an If of 9A and a Vf of 3.6V. the simplest way to connect them would be in series, using 2-4 devices. if the power supply has a current limiting function, you set it to, say, 7A, and just crank up the voltage until the current-limiting kicks in (around 14.5V if using 4 devices).

if you dont have current limiting, then the best way is to wire them is in parallel, with each LED having a series power resistor. so, say you set the voltage to 6V, you'd need a 0.33-ohm resistor rated at 25W or better.
R=(6v-3.6v)/7A=0.34ohm,
P=(6v-3.6v)*7A=17W

Anonymous Wed Oct 21 11:58:18 2015 No.891293
File: 1.00 MB, 2048x1536, tmp_13692-20151021_140827-705297347.jpg [View same] [iqdb] [saucenao] [google]

Which is the backward voltage ant which a white LED gets destroyed? I'm working on a little lamp with 15 LEDs in series and I was wondering what would happen if the polarity was inverted and the voltage increased. If they're not safe I could add a 4007 diode to avoid destroying them.

>>	Anonymous Wed Oct 21 12:57:43 2015 No.891314 http://www.ebay.com/itm/191467000119 is this transistor kit worth the price? if not any ideas on what would be a good deal. thanks.

Anonymous Wed Oct 21 13:41:59 2015 No.891324

>>891314
I'd say so. Those are pretty common and they're sorted for you. BJTs aren't really static sensitive and are pretty rugged so the case is fine and they'll probably all work. You won't be using them for power or anything crazy like that, but they'll be fine for logic or low amplification.

Anonymous Wed Oct 21 13:50:15 2015 No.891330

>>891314
Also if you know what you're doing, 2N5551 is a good batch to find avalanche transistors in if you have an oscilloscope and can make a test circuit without destroying them. If you can find a couple in that 40 piece set then you definitely got your money's worth. Just remember to drive the base and not overload the Vceo breakdown voltage if you so use them as avalanches.

>>	Anonymous Wed Oct 21 14:14:44 2015 No.891346 >>891330 >>891324 Thanks. Greatly appreciate the quick response too.

Anonymous Wed Oct 21 17:46:44 2015 No.891462

is there a website or youtube channel that shows and explains the working of some basic circuit snippets like, say, a capacitance multiplier, an oscillator, or an audio delay, flanger etc...?

Like basic circuits that normally appear as parts of bigger circuits but that are nearly always the same, and the mathematics behind them.

>>	Anonymous Wed Oct 21 20:24:13 2015 No.891504 >>881118 Looked up the EVK1105, it's too expensive, I can make do with a cheap LCD screen. Haven't read the datasheet for the AVR32 but it looks like I might need this. Thanks for the suggestions!

>>	Anonymous Wed Oct 21 21:15:23 2015 No.891521 >>881299 Roll

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