Amplifier Help

Starhawk wrote 05/24/2017 at 22:24 1 point

First, an artsy photo with schematic.The volume control is in the notched-in area. It's a little thumbwheel (trimpot) getup. The red and black wires nearby run to the battery holder underneath with a single AA in it.

Here's a better shot of the schematic...

I admit one mistake already -- the 150R resistors are supposed to be 150K resistors (oops!) per the original (mono) design, here -->

The left side of the schematic is the input side, with outputs to the right. (Apologies for the poor labeling.) Those 100nF caps are standard MLCC jobs. I added the huge electrolytics (left over from a mobo rework project that was abandoned; they are rated 6.3v, BTW) on the theory that they might help drive speakers/headphones, since a large value electrolytic is usually required to drive such things from e.g. a microcontroller pin.

Alas, this amplifier does not amplify -- it rather seems to whisper where I want it to roar. I'd like to be able to drive standard headphones with it, although my current 'dummy load' is a pair of unamplified speakers left over from a 2007 eMachines system that has otherwise long since gone skyward. The actual physical speaker units inside the eMachines-supplied case indicate that they have 16R coils, although I don't have a photo of that.

Perhaps someone can tell me what I need to jostle around to make this amp at least holler if not roar, rather than whispering quietly...? :-/