audioguru Posted May 10, 2005 Report Share Posted May 10, 2005 Hi Guys,We have a nice new audio power amplifier project:http://www.electronics-lab.com/projects/audio/041/index.htmlI think the author makes an error when he says to put a current meter on the output and adjust the trimpot for zero current reading. I think the adjustment is to reduce offset voltage at the output to zero so there isn't a DC voltage on the speaker.I don't see any temperature compensation for the output transistors like nearly every other audio power amp includes. Temperature compensation prevents thermal run-away. As the output transistors heat-up during normal operation, the heat causes their base-emitter voltage drops to decrease, causing them to draw more current. The increased current causes them to heat-up more and draw even more current and around and around it goes getting hotter and hotter.I also don't see any emitter resistors for the output transistors like nearly every other audio power amp includes. Emitter resistors would help equalize the gain of the output transistors and they reduce the tendency for thermal runaway.A 741 opamp? I won't say anything until someone carefully listens to the amp. ;D Quote Link to comment Share on other sites More sharing options...
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