BuffaloEngineer
Member
The mic will not work without a preamp. The resistor that powers the mic must be 4.7k or 10k.
The circuit will not be very loud with 8 ohm to 32 ohm headphones because the opamp cannot supply enough current and the 100 ohm resistors limit the output level.
Points taken - I've updated the schematics and tested it, and the performance is much better. Thanks very much for all the help!
I did have a couple lingering questions - do I need a resistor at the output of the amp going to the headphones? I read that I might need one to prevent a short from frying the op amp when the headphone jack is inserted - in this case the short would just discharge the 100µF (C5) cap to ground.
Also, I put in a 47nF (C6) cap in series with a 10Ω (R11) resistor at the output of the op amp going to the headphones because I saw it in an example circuit. Anyone know what the purpose of this is? Thanks!
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