I'm building an audio amplifier using an LM386. According to its datasheet, I should connect the LM386's output through a 220uF coupling capacitor to the 8 ohm speaker.
If I use a 220uF polarized electrolytic capacitor (the only kind of capacitor of this size at the local Radio Shack), should I connect the + node to the LM386 output, and the - node to the speaker so it won't explode?
Also, will there be any problems with initially charging the capacitor when power is first applied?
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The LM386 uses a single ended supply, +5 volts and ground for instance. The answer to your question is in the datasheet located here:
Look at the typical applications on page 5...
The 386 has internal bias resistors to set the average output voltage at about half way between its positive and negative supply rails. If the speaker connects between this node and the negative rail, then the positive side of the capacitor goes to the amplifier.
There will be a brief pop from he speaker as the capacitor charges to half the supply voltage. If this is bothersome, you can replace the single capacitor with two 100 uf caps in series across the supply, with the speaker connected between their junction and the output of the amplifier. This puts half the supply voltage on the speaker.
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