/diy/ - Do It Yourself

Vacuum cleaner motors run really fast with very little torque. They aren't going to be able to turn wheels unless you add a reduction gear system, and cobbling together a set of gears from spare parts can be a nightmare. Also unless you're getting them a battery powered vacuum they will be AC motors, which you can't run off of a DC battery with a lot of hardware.

Find yourself some DC motors with gear systems already on them like ones from car power windows, electric wheelchairs, or battery powered drills.

>>do you think some opto-isolation will be ok
You shouldn't need opto-isolation

>>we'll have little idea about what motor controller to use.
You'll first need to know the voltage and current of the motors. Once you do go to: search.digikey.com/ca/en/cat/integrated-circuits-ics/pmic-motor-and-fan-controllers-drivers/ then select the properties you need from the dropdown.


>on a side note might the image processing for a laser scanner be ok on a Raspberry pi or do you think it would overwhelm it?
I've built a laser scanner with hardware far inferior to the rasberry. http://www.odec.ca/projects/2004/kram4r0/public_html/scan7.html

>>168076
I understand your question now.

>>I don't see an output buffer in the schematic of the chip, so i'm not sure and I can't see how the existing state could remain without a buffer.

There's the input shift registers and the PWM output registers. Loading data into the shift register doesn't effect the data in the output registers until you pulse the Xlat pin. The duration of the Xlat pulse should be at least 20ns; its not dependent on any clock inputs.

>>168060
There's no feedback from a servo or an LED to a controller chip like that. You can force the servo into any position, turn it off, or light it on fire; the 5940 will keep on outputting the same PWM.

Firewire should do it; or just run a wire from your PC's power supply out of the case.

>>168046 My understanding told me the potentiometer/op-amp circuit was to allow the servo to cross reference its input signal to what the shaft position is, and modify accordingly, nothing more. PWM gets converted to a voltage, which is then cross checked to the potentiometer reading via an op-amp. If a pot position is greater than ref voltage (ie, the average of the PWM signal), wind the servo back till it matches. If its greater, wind it forward till it matches. Hell, even the guys at the hobby shop said there was no such beast when I asked today while buying servo's.

Am I reading something wrong? If you already understand how a servo works why are you asking if it will return to its original position after being moved by an external force? Do you mean you want a servo that holds its new position after some external force moves it there, not one that snaps back to where it was?

>>167986 will it hold and return to 70 degrees if it is forced away from this position by external forces like someone manually moving an arm or leg.

Yes, but this isn't a special feature of the 5940. All servos will behave this way. A servo contains a DC motor, some gears, and a potentiometer connected to the output shaft. The internal circuitry reads the PWM and uses its pot to send the shaft to the specified direction. If you force the shaft to move it will try to go back into place.

1) Look very carefully for a switch. You wouldn't believe how often perfectly working equipment ends up at freegeek because the owner just didn't know how to turn it on.

2) Open it up and look for a broken fuse. Not many modern electronics have those; but do it anyway.

3) Look for a popped capacitor. There's this thing called the capacitor plague going on because so many shitty capacitors were used during the last decade.

>>165135
One of my recent projects: Thirty solar powered motion and sound sensitive strings of 100 fully addressable RGB LEDs. Makes a big wave of rainbow lights when a person goes by underneath or a train above. Designed to last at least ten years without maintenance.

http://organelledesign.com/lightmodal.shtml

>>165054 a typical way to mark a 100n cap would be 104K, not 1K4

Its not seen much anymore but values are still written like that sometimes. Its a notation engineers developed to save time. 2.2K resistors are 2K2, and 100nf caps with a 0.1% accuracy are 1B5. I've found a diagram for you that uses both notations interchangeably. Letters do not indicate value. They are accuracy. There is a system for reading capacitors and that's how it works.

http://lmgtfy.com/?q=how+to+read+capacitor+codes

>>165052
My bad B means 0.1% accuracy, not 0.1pF accuracy.

>>165046
Values are not given by letters. The letter codes are accuracy. Just google how to read capacitor codes.

>>165028 Probably 0.1pF
Isn't that exactly what I wrote?
>>164869 The B means its within 0.1pF

>>165028 At least neither of the markings doesn't mean 100nF.
The markings mean 100nF +/- 0.1pF. This isn't a guessing game. That's how you read capacitor codes.

Letter is accuracy. Last number is power. First number(s) are the integer. It gives scientific notation in units of picofarads.

>>164725 1B5
The B means its within 0.1pF of the specified value.
The 1 and 5 mean it is 1*10^5 picofarads = 100000 pf = 100nf

The other numbers and letters are just a manufacturer code. They are not important.

>>163380
One of Graham Bell's first inventions/experiments was to force air through the windpipe of a goat to produce screaming sounds. It irritated his neighbors. Great progress ensued.

>>162101
The local small ISPs connect to larger ISPs, not the backbone directly. Nonprofit ISPs usually do this too and require funding from donations and grants to stay running.

Get yourself a computer and throw four video input cards into it or use webcams or ethernet cameras. There's some free software out there for managing a security camera system like this.

>>162084 Internet without ISPs

That would mean connecting to the internet backbone directly. The purpose of an ISP is to connect a smaller regional network to the backbone. Connecting to the internet backbone will require you to pay many millions of dollars to the company operating the section you're interested in; and of course build your massive computer complex on top of the existing backbone or lay out millions of dollars of your own fiber optic cable. This is not a practical idea.

Get yourself a non-profit ISP or steel someone's ISP account.

>>161787 If only we had our own searchable interface that had a memory too...


http://archive.installgentoo.net/diy/

I've got some old lab equipment that sort of meets the description.

If you want to build your own I suggest getting a flange like this and putting it in a metal box.
http://www.princessauto.com/pal/product/8067571/Tail-Lights/4-in.-Stainless-Steel-Trailer-Light-Flan
ge-Mount

You can make a really ugly hole with a drill and file and it will still look professional because the flange covers the edges. Use an LED to light up a piece of plastic with graphics on it for the display. Put switches and indicator lights in other places.

I've got some old lab instruments that meet the general description.

If you want to build your own I suggest you get a metal box and put a flange like this on it for the screen:
http://www.princessauto.com/pal/product/8067571/Tail-Lights/4-in.-Stainless-Steel-Trailer-Light-Flan
ge-Mount

You can make a really ugly hole with a drill and file if you use a flange because it covers the edges. Behind the flange put a piece of clear plastic with some info drawn on it; light it up with an LED. Throw a bunch of switches and indicator lights on the rest of the box.

>>161151
>>161152
Try googling the writing to bring up a datasheet. Without a datasheet you won't even know which wire is ground and which is power.

It is often not possible to find datasheets on components pulled from electronics online. Companies like to keep some things confidential. There was a contest on SparkFun a while ago to get a random cellphone camera to work with no datasheet. The winner had a lot of experience and put a month of effort into it.

Just because two devices are on separate breakers doesn't mean they are electrically isolated. You probably created a surge through your house wires that was either too fast or not powerful enough to trip the breaker before damaging the computer.

Can you find a datasheet on it and do you have microcontroller experience?

>>161119
>>161118

If you want the PDA to be able to use wifi, bluetooth, or any other radiocomunications you'll need to use a faraday cage with holes bigger than those wavelengths. An EMP at those same frequencies or above will get through. EMPs tend to be white noise; spanning a large spectrum; so you can give some protection to a wireless device; but nothing completely solid.