My project involves sounds from boards salvaged from children's toys running at 3v~5v. These need to be much louder. I have built a circuit with LM386 (How to Connect a LM386 Audio Amplifier Chip to a Circuit) without success. I assumed that audio input was from the +/- speaker wires of the toy to the 386. Is this correct?
That is correct, however you may want to couple into the input through a capacitor to remove ant DC on the input signal.
Thanks for the advise. To be sure I understand correctly, should a cap be placed across pos to neg of these two wires from the toy board speaker to the 386 amp circuit. Also, should the grounds of the two (toy and amp) be joined, or is this already happening with the ground speaker wire when connected to the amp circuit?
No the c should be in seriese with a speaker lead.
The -ve speaker should be ground. If it is not then connect the grounds together and have another c in the -ve input as well.