The Dimetrodon Distortion - In Miniature!


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Build Rating
5.00 star(s)
I was looking for a way to take one of my own pedal designs and streamline the production a bit. Most commercial pedals, and honestly many of the independent one-person operations, are using predominantly SMD boards. While these aren't nearly as much fun to build (and aren't nearly as cool in my personal opinion) as through-hole boards - they can be mass produced and assembled more quickly. So I fired up EasyEDA and spent a lot of time looking through components... and the Dimetrodon Mini was born...

Dimetrodon Mini - 01.jpg

Although I'd laid out several boards at this point, including the one for the Dimetrodon Distortion Deluxe, those had all been laid out entirely for through hole components. I'd never attempted to lay out anything with surface mount devices before, so there was a little bit of a learning curve. Many of the components of the Dimetrodon are normal resistors and capacitors, so it was easy to find appropriate parts to add to the schematic. I was even able to find an appropriate op amp, and some tantalum capacitors so I matched the original as closely as possible. I knew, however, that I wouldn't find the appropriate germanium diodes, so those remain through hole - as is the transistor for the gain recovery stage. The boards arrive pre-assembled apart from those through hole components and then I add those key bits myself from the stocks for the normal through-hole builds.

Dimetrodon Mini - 02.jpg

I built my first prototype (not pictured) using my normal Switchcraft jacks and a separate daughter board for the stomp switch and LED. However, looking at most production pedals (especially those in a smaller form factor with side-mount audio jacks) it's typical to see the audio jacks, LED, and stomp switch (at least) on a separate daughter board. This reduces the amount of hand wiring that has to be done saving build time. The one drawback of most of these designs is if you use the PCB mount audio jacks, the pedal itself is not grounded to the enclosure. Fortunately I'd laid out the main board with several extra ground holes (so I could freely move to different form factors as needed) and I was able to find a ring connector with the correct inside diameter that I could use as a washer for the input jack and wire it to the main board. This grounds the whole pedal to the enclosure.

Dimetrodon Mini - 03.jpg

The enclosure itself is smaller than the normal Dimetrodon Distortion enclosure (hence the "mini") and has a very fun piece of dimetrodon art on the front. This one is licensed rather than one I commissioned for the pedal. If these end up taking off, I may change the art going forward... or I may not - it's kind of cute!

In terms of the sound of the pedal - it's a Dimetrodon Distortion through and through. There may be a slight bit more background noise as compared to one of my top of the line all hand-built through-hole versions, but it definitely holds its own. For this run, I used the Sovtek tone stack, which shifts the mid scoop a bit toward the treble relative to the '75 Ram's Head. It's a really solid build with a lot of versatility.

Dimetrodon Mini - 04.jpg

Honestly the real questions at this point are economic... I'll see if enough people actually want an SMD dimetrodon, or whether they'd prefer the all hand-built version. Either way it was a fun experiment. I've now laid out a board using surface mount devices, and created a unified stomp switch, LED, audio jack board so there's very little wiring on the inside of the pedal as well. It gives the inside a very clean look if nothing else!

Original blog entry (with more rambling and so plans going forward):
Great job! I've wanted to use EasyEDA to get some simple smd boards made, but I had a hard time figuring out the parts, specifically what size/type of smd caps and resistors to use.
Great job! I've wanted to use EasyEDA to get some simple smd boards made, but I had a hard time figuring out the parts, specifically what size/type of smd caps and resistors to use.
Honestly that's what took the longest - especially the capacitors. I had to sort through a LOT of parts...