Playing around with this little audio amp, I came up with a nice simple little 3-transistor amplifier that drives a set of headphones very nicely.
**broken link removed**
I like it because 1) it's simple, 2) it only uses 3-legged devices, and 3) it can be built from parts in your junk box.
I listened quite a while with this running on a 9 volt supply, and it sounded good to me. It took a while to tweak the input attenuator network (R1 & R2) so that it wouldn't be too loud, the volume control would actually work (instead of acting as an "on-off" switch) and the input would be inaudible with the volume control at its leftmost position.
I actually ran this without any output coupling capacitors with seemingly no ill effects either on my headphones (mid-range Koss) or my ears, so I'm not convinced they're absolutely necessary.
I powered this with Mr. Al's simple 3V--> 9V boost converter, which worked great. (Had to throw about 1000µF of filter capacitor across the power rails to quiet it down.)
**broken link removed**
I like it because 1) it's simple, 2) it only uses 3-legged devices, and 3) it can be built from parts in your junk box.
I listened quite a while with this running on a 9 volt supply, and it sounded good to me. It took a while to tweak the input attenuator network (R1 & R2) so that it wouldn't be too loud, the volume control would actually work (instead of acting as an "on-off" switch) and the input would be inaudible with the volume control at its leftmost position.
I actually ran this without any output coupling capacitors with seemingly no ill effects either on my headphones (mid-range Koss) or my ears, so I'm not convinced they're absolutely necessary.
I powered this with Mr. Al's simple 3V--> 9V boost converter, which worked great. (Had to throw about 1000µF of filter capacitor across the power rails to quiet it down.)
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