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Project Notes

#096 Smokey

A quick build of a Smokey-like LM386 guitar power amp.

Here’s a quick demo of the circuit in action:



The Smokey is pretty much the grandfather of a range of LM386-based guitar amps, like the “Little Gem”/A386 variant by General Guitar Gadgets .. see my build here.

So I thought I’d see what the Smokey really sounds like. This circuit uses the details from this analysis to do the build. The 47μF C1 is required to correctly bias the input since we have a direct connection from guitar to the op-amp input.

I had to make a couple of variations to get it to work properly:

  • I had to remove the short from pins 1-8 of the LM386 because it couldn’t handle the gain. Without the short, the amp runs at the default 20x.
  • adding 100μF C3 filters noise from the power supply. This is essential with a switch-mode 9V adapter, not required with a battery.



The Schematic

The Build

Credits and References

About LEAP#96 AmpAudio
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.