You sometimes hear electronics types talk about “jellybean” components. They’re not necessarily referring to the shape, so much as that such parts are likely to be stocked on hand in reasonable quantity in even a modest electronics lab, often in bins to be dispensed as needed like candy. The 2N2222 transistor, 555 timer, and ‘741 op amp are other such parts.
The LM386 audio amplifier is one such “jellybean” part. Although as a digital partisan, when I hear “386,” I think of the Intel 80386, the LM386 audio amplifier chip is a very useful part for projects that include a speaker.
The LM386 is straightforward enough to use: Provide ground, suitable supply voltage (5-12VDC or so), and a low-level audio signal on the non-inverting input. Leave the gain pins disconnected for the default gain of 20, and connect a speaker via a 250uF series cap, with a 500nF+10R series pair to ground from the output, and you’re good to go. The input is nice and high impedance, so it can be driven by pretty much anything.
