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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

Project Source on GitHub Project Gallery Return to the LEAP Catalog

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. Two main themes have emerged in recent years, sometimes combined:

  • electronics - 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
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.