I'm rather new at this whole thing, so bear with me. Alright, so I needed a basic power supply and decided to use a wall wart. I desoldered the female piece from and old piece of junk sitting around, and I want to use it, but I'm not sure what all three prongs are for .. anyone?
Edited post, because I realised what I said was stupid as I hadn't understood the post properly Welcome to Bit-Tech anyhoo
Welcome to Bit-Tech forums, newtrickz The female end you have probably has a built-in switch to turn off a battery supply when the wart male plug is pushed in like this one. Wallwarts are fine for getting the mains down to a safe level, but an un-regulated design will put out a fair bit more voltage than what it says on the label at low current draw (like if testing leds). Add a regulator or use with caution.
if i knew which prong was which, which i'm not *quite* sure about, how would i go about wiring it? just ignore the switch because it turns off the batteries and that's all?
Try utilizing a voltage meter or a resistor with a LED to gauge which side is positive/negative. The third leg may either be positive, negative, or a stabilizer.
there is a good set of jack pictures here: http://www.dixel.co.il/Astron/Power Jack.htm if you click on "technical drawing" it will show the internal schematic. chances are your jack is there.,
Or the ghetto way. Solder 3 wires to the socket, stick the bared (down to copper if tinned) other ends in a slice of potato, about 1" apart in a triangle. Plug in the wart. After a minute or so, positive will show some greenish dicolouration and gas bubbles, negative should just produce gas bubbles, switch wire should do nothing.
Yay. I just tested it with my DMM and it worked fine (I didn't want to do it before because I wasn't sure if it wasn't a smart thing to do for some obscure reason). I measured 9.17V (+1.9%). So what was the deal with the regulator again (i.e. what actually happens, you mentioned something about it occuring with low current)? And do you think it's plausible for an electronics noob to do it? I basically just want the wart as a stable PS for my soon to arrive breadboard.
Now that is cool! ...off to try that with my wall wart and a potato... (even though I know which wire is which on my wart...)
Assuming it's a 9V wallwart, that sounds like it's well regulated already, which is fine for a lot of circuits and cheaper than PP3 batteries. If you need a 5V supply for some logic chips, then you can make up a cheap & simple 5V regulator that will reduce the 9V to 5V.
Adding a voltage regulator is easy, especially on your breadboard. It's a small 3-pin component. One pin goes to the 0v rail on your circuit, and the other two are connected in series with the line you want to regulate. Basically, it acts as a variable resistor of sorts, varying itself to ensure the voltage between its output and the pin connected to 0v is 9v. The only problem is that most 9v regulators have a minimum input voltage of about 12v, so you'd have to find one with a low dropout voltage... I'm sure someone here can find a better solution.
