LM386 Operational Amplifier
Audio amplifiers come in all shapes, sizes and specifications. We have quite a few different chips in the buckets of components which will see the light of day on this blog. But the very first audio amplifier I built from scratch on a breadboard featured the venerable LM386 opAmp which has been fueling hobbyist dreams since 1969.I only half read the datasheet (??) so I fed it 27V and popped a few before I realised that I was way over voltage. Fortunately they come in for about AU11c each so it was no big deal to blow a few up in the interests of science?
After a bit more digging around I was able to obtain the LM386N-4 which according to the datasheet should make the most noise.
There are a billion examples of this circuit out there in cyber-world, but I returned a few times to this page and the circuit shown below (which is simple and works well).
This site has such a great tutorial and you can keep adding components to make the sound louder and sweeter. I recommend that if you're serious about these audio amp circuits you head over to the site rather than look at my efforts as I'm only trying to look at how these opAmps might be used. As the original IC was designed for use in an automobile as part of a fuel injection system there might be a few more blogs on this site with this component in other guises.
In the meantime, this is the circuit that I decided to build (with the swap out of 12V for 9V and the LM386N-4 for the standard LM386 opAmp).
If you're unhappy with the sound quality of the amplifier in the video below, remember it's coming through a cheap old speaker and then into a cheap phone microphone. It sounds better in the real world and in fact it has been chugging away on the kitchen bench providing background music for the last few days.
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