00940
HeadWizerJoined: Nov. 5, 2002
Locale: Belgium
Total Posts: 173 |  posted 03-17-2009 03:28 PM CST (US)   |  | 
Here is a very cheap but surprisingly decent little amp. It can probably be built with the parts in your junk box. It's somehow similar to a Eaton (see library).
Some explanations:
- the input pot is a 100K linear one. Interaction with the input resistors gives a usable (not perfect) curve for audio.
- Offset varies between 13 and 3mv in one channel, depending of the position of the pot (the other channel is in between 0.8 and 9mv).
- Input impedance is kind of low at min 13K
- The signal is taken from the pin5. The jfet ccs which biases the ne5534 also biases the led for the class AB output stage.
- The emitter resistors' value is a bit high at 33r. I picked the value according to the forward voltage of the leds I had in hand. It gives me a bias of around 12ma.
- Power supply can be about anything in between +/-9 and +/-15VDC. I used a 24vdc wallwart, regulated by a lm317 to 18v and split with a passive rail splitter.
- Some additionnal decoupling isn't shown. Original idea from here: http://www.diyaudio.com/forums/showthread...
Attachment: C4763.GIF |
