Wednesday, April 8, 2009

cmoy pocket amp


so, my buddy cameron wanted to make a pocket amplifier to use with his ipod (you can never rock too loud... unless you blow an ear drum, which is too loud). he found this well done tutorial over at tangent soft. we got the supplies and started assembling on my bread board. the problem is i haven't touched a real electronics project since university. this was one of several factors that led to a series of problems. here they are in chronological order:

1. one of the capacitors blew up when i put it in backwards
2. the volume knob (potentiometer) was a linear pot and was only for one channel.
3. the voltage splitter went all crazy when the headphones were plugged in (i.e it sounded terrible)
4. once we soldered it up the right channel wasn't working properly.

the capacitor fix was easy: don't be an idiot. the volume knob took some more work as i had to trek all over town trying to find one. when i finally did find one it was super old school with no schematic online, so i had to sort out what pin was what myself. that is probably easier for someone who knows what they are doing. cameron solved the voltage problem. apparently he has very low impedance headphones and there was a significant offset current (i.e. the amplifier needs a certain voltage range to operate and the headphones where mucking it up). so, a couple of electrolytic capacitors later the problem was fixed. we haven't fixed #4 yet, although i should have some time today. i'll keep you posted. here are some pictures of the progress:


it was one of those black capacitors that blew it's top.


adjusting the volume.


cameron trying to decide which "gain" is best.


enjoying the fumes.

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