Can anyone assist me with the LM386 circuit. All examples I see for this circuit only address an output of 8 ohms for a small speaker. I would like to use this ckt to addapt an electrovoice 638 mic to about 1300 Ohms my Icom 730 requires as a mic input.. wondering if a xfmr would do it. If so what would it be.
Not a problem, this is audio, not RF. Just tack a 1K resistor across the output of the '386 and then attach to the radio.
In audio applications, we can always apply a lower impedance into a higher impedance. It won't work like that the other way around, though as trying to drive a low impedance input with a high impedance output will load down the signal.
The opamp is high impedance at input, but low impedance output.
No transformer needed at all here.