The LM386 TI applications notes page 11 show an amplifier. Would like to use this chip with complete isolation of the output speaker and with the addition of an isolated input speaker. Am using impedance matching transformers on input and output for speaker isolation from the power supply. Should the 10 mfd shown be polarized?
Yes, the 10µF capacitor between pins 1 and 8 can be polarized, but it doesn't have to be. If you use a polarized capacitor, have the negative side on pin 8.
This will give you a gain of 200. If you want a different gain, you need to add a series resistor.