/diy/ - Do It Yourself

>>228554
An off-the-shelf controller is perfectly usable. I added a motor to my bike with one.
Factory-made controllers are cheaper and smaller than anything you will ever make. And you will avoid any costly disasters such as when a bug in your code suddenly destroys everything. It is actually better to expand the possibilities of your controller with additional circuits applied to the throttle signal still.
Oh, and I have over 1000km on my electric bike now and no "timing problems."

I'd say this is a bad idea. Not only you can already push it deeper as he already suggested, but having the handlebars low will make your back uncomfortable. People often seek ways to actually raise the handlebars above the factory limit.

http://www.intimategadgets.com/product/waterproof-body-massager-for-him-9.5cm-length-42642

5 bucks with shipping included!
Thank me later.

One of the final stage transistors is fused short. You can find it with a simple multimeter set on low resistance range. Unsolder it, check again, buy a replacement by its number.

>>225700
The above is me. I also wanted to add that a buff-tailed bumblebee is protected, but it is still the most common of all bumblebees. Remember this stripe pattern. If you ever find a nest on your property with different species (which would be rarer), I suggest that you leave them to finish their season. They will leave on their own in August. If the nest was unwanted, close any holes in the terrain after they leave so that they won't return next year.

>>214498
I suspect you are lying/trolling. Can you back up your claim by an internet link? Because I know what I'm saying is true from experience.
You also seem to model me as a collective imaginary friend of sorts - I did not make efficiency a big deal at all, it is often used as an argument though. The internal resistance, which you wrongly implied as being the same as stability, is indeed a problem and you get to ridiculous sizes for the transformer to control it.
Not to mention that even if you did use an oversized transformer, you would still have problems with the 50Hz ripple and with the tolerance for the mains voltage. Thus your transformer would also have to have a multitude of taps to accommodate it to most powering situations.

Don't ever use lye on a drain that is clogged this much. And if you do, make sure you dissolve the granules fully before pouring it in. LYE CAN SOLIDIFY LIKE GYPSUM and make an expensive plumber job inevitable! I experienced it myself. But we drilled the solid hydroxide out of the fittings so that we weren't forced to buy new stuff. Be careful!

>>213874
It is an equivalent of $20 and here in the Czech Republic we don't have as much money to throw out the window, so many people don't even buy Koss phones.
I have actually fixed mine myself a few times, it's always either the cable or hairs under the grills.

>>214287
Implying I ever denied the presence of a ferrite transformer in a switching power supply. You should have presumed I knew by the rest of my post, namely the differentiating between the two core types. Also I didn't know it was called a linear supply, probably because English isn't my first language. What a surprise on the internet.
Iron core transformers make for less stable power supplies because 1) it is very hard to filter 50Hz as opposed to 40kHz, for instance and 2) they operate with a fixed pulse width as dictated by the mains supply. Voltage stabilizers are inefficient. And I don't count in DC-DC converters with coils because those are already border-line switching supplies and they don't fit the concept of an old-school transformer at all.
I also stand by the need for an oversized transformer because +-20% in voltage used to be acceptable back in the days and these transformers have this inaccuracy by design.

OP, if you decide to use a plain iron core transformer as hinted in the pic, you will need a ridiculously huge one. Today's electronics expect a much more stable voltage than was available at the time of iron transformers. Your piece would have to weigh over 10lb to handle the power.
If you decide to use a switching power supply, you must not try to make it from scratch: Building a power supply is a thesis material for a reason. If I was you, I'd take a used computer PSU and create a -12V rectifier (use fast diodes) along with the corresponding windings of the coupling coil (wind the same amount as +12V, but connect in reverse). This should give you a strong 24V supply complete with a grounded metal box with little fuss.

>>213528
Not a good explanation. With bipolar transistors (which you mean), it is the current flowing from base to emitter (NPN style from now on) that opens the transistor. The opening can be used either as being from C to E (in most cases) or from C to B in high-frequency applications.
Unipolar transistors have their gate (like base) insulated from the rest, so the voltage between G and S is what opens the transistor. Current then flows from D to S (N-channel). Common gate configurations still exist, but they are a kind of hack since they leverage the capacity of G to make the whole thing behave like a full-fledged double-brane for high frequencies.

>>213549
I know about the warranty, but unlike you, I also know that it is with a rather high fee around here. It is not a really free lifetime warranty, but they still call it that.

>>213551
The damage is actually covered too, but that's probably why they introduced the fee.

As for the jack:
Heel/Sleeve: common negative
Ring/Middle: right positive
Tip: left positive

You could just try and connect a weak power source (a single AA cell) to each pair of wires with the phones on your head. When you hear a click in the left ear, you know this pair belongs to the left side. But this method won't tell you the polarity, so you remove the blue plastic lids on the backs of the speakers (they are connected by just push-pins, pry it with a pointed knife) and use an ammeter to find out what is connected to what.You may well discover at this stage that one of the wires is broken somewhere along the cable.

OP, you shouldn't just connect the tweeter directly like that. Although it won't play the lows, it will receive their power and turn it into heat, then not only taking the power from the other speakers, but potentially burning! The easiest way to fix this is to connect a cap in series with the tweeter. A 2uF mylar is a good start. It won't be as good as a proper band filter, but should be passable.

A tricopter is better than a quadcopter in that you only need off-the-shelf components for ordinary helis. The most exotic being a hardware 90° to 120° swashplate converter - and that one can even be substituted with more gyros (3+converter or 4 gyros ), so if you buy cheap DX gyros, it's even better. A quadcopter, on the other hand, requires an ad-hoc mixer. Its only advantage is that it can work with no rudder servo.

The LiPo battery would be an overkill for your power needs. The real problem is the price of the charger. You cannot use a regular charger or the LiPo battery will cause fire!
This means that you will pretty much have to buy the cheapest lead battery available.

The reason why your friend's circuit doesn't burn may be the polarity of the phone line. It has alternating voltage with bias in it, making a circuit receive different voltage depending on the polarity. This is how they make it in my city.
Using voltage regulators may not be a good idea due to the high ringing voltage. That's why they used a transistor in the first place.
I'd just perhaps try a resistor of higher power rating.
Using a transistor with a zener diode is common practice even in today's hi-tech consumer electronics. I have replaced one such thing with the 7912 just recently.

The soldering pads for the jack are probably torn off the PCB. That is a bad condition. Your best option then is to find a larger copper area where the bad spot used to be connected to, solder a thin wire to it and connect it to the connector. Do not attempt to bridge the pad with its adjacent torn off trace, that would tear very soon under use.
If you are lucky, only the contacts inside the connector will be dirty. Bend them inwards to improve pressure, scrub them carefully with a drill-bit (in hand, not drill).