LM386 Utility Amplifier

It's always handy to have a little amp kicking around to trace audio signals, test mics, CD tape and TV audio outputs. You know, something that doesn't weigh a lot and isn't clumsy. There are tons of uses for this little circuit. There are a couple of versions of this amplifier chip. Both are 8 pin DIP packages and the difference between the two are apparent by their part numbers. Either are suited for this circuit provided the supply voltage does not exceed the recommended 5 to 12 volt DC range. Power output can range from about 325 mW to about 750 mW within this supply range when using an 8 ohm speaker. Power it with batteries or a small DC supply...why not solar cells or a little windmill generator?

The circuit shown has gain of about 200. VR1 is the volume control. The voltage rating of the DC blocking capacitor C1 should exceed the supply voltage of any piece of equipment you want to probe if you're using this as a signal tracer. Tube amp circuitry supply rails can exceed 600VDC, so make sure you choose C1 with this consideration in mind.

Parts
C1, C2 10uF 16V electrolytic
C3 .1uF capacitor
C4 .05uF capacitor
C5 220uF 16V electrolytic
R1 10 ohm 1/4w resistor
U1 LM386 amplifier
VR1 100K "A" taper pot
SPKR1 8 ohm speaker

Seen on electronics-diy.com