The Crank by Mark Hammer

The Crank by Mark Hammer

This is interesting variation on the Tube Screamer style diode clipping. Read more about it at Mark Hammers site here: https://hammer.ampage.org/files/The_Crank.gif

In a nutshell the goal seems to be less distortion. More of a booster to overdrive effect. I’d say this circuit meets that goal. The sound is mostly clean with some gravel or grit as you get louder. It never gets fully distorted.

My Schematic of The Crank

The Build

I designed the PCB in Eagle. Then had some boards manufacture at PCBWay.com. The cost was $50 for 10 boards, which is seriously cheap. The shipping costs were $20. By ganging this order with a couple other orders I kept the costs down to $1 per board. So $10 for 10 boards is better than making the boards by hand.

Sadly I mixed up the pots so the rotation is backwards. While I could fix this by cutting the legs on the posts and soldering some jumpers, I think I I’ll just make a new version of the board in the future. There were a couple other improvements I also want to make.

I designed the board with the pots and LED mounted to the board and off board wiring at the bottom edge. This makes for a very easy build.

I designed the graphics in Sketch and milled the enclosure on my desktop mill.

Last I wired everything up. With the offboard connections organized along the bottom of the board the build process is easy and prevents errors.

I may publish this one to the shared service but it will need an update first to fix the pots which operate backwards.


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