Electronics > Beginners
power amp circuit
NASK:
Hi
I need to design simple power amp circuit using Darlington class AB push-pull amplifier with having input resistance 10k to drive 8 Ω speakers. I followed book Electronic devices Thomas L. Floyd and it gives Rin = βac(r e + RL) // R1 // R2 (page 356) equation to design it. In my design output gain is reducing in results, how correct this issue.
Zero999:
There's some crossover distortion there. Add some emitter resistors to the output stage and increase the base voltages by reducing the resistor values, adding an extra diode or a BJT with a VBE multiplier.
HB9EVI:
Hmm, don't you maybe need some voltage gain too? there's no voltage gain in this circuit, thus not much power gain, if the input signal doesn't already have sufficent amplitude
NASK:
--- Quote ---"There's some crossover distortion there. Add some emitter resistors to the output stage and increase the base voltages by reducing the resistor values, adding an extra diode or a BJT with a VBE multiplier.
--- End quote ---
Therefor i change the value but required input resistance is 100k , current system has 247R how improve it?
--- Quote ---Hmm, don't you maybe need some voltage gain too? there's no voltage gain in this circuit, thus not much power gain, if the input signal doesn't already have sufficent amplitude
--- End quote ---
I do not need voltage gain it is doing by pre-amp. pre amp circuit have sufficient amplitude.
Zero999:
The output stage should be in the feedback loop of the entire amplifier circuit, which will both boost the input impedance and reduce the distortion.
Those compound output transistors might not be needed. A similar thing has been done before, see the following thread:
https://www.eevblog.com/forum/projects/guitar-headphone-amplifier/
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