Distortion pedal #1
Category: Pedals
2016-01-28 11:11:17
This is my first guitar pedal build - I've gone with what looks to be a pretty simple single transistor plus diodes distortion circuit.
Not knowing where to start, I basically typed 'distortion pedal' into my favourite search engine, and went from there. There are some really bad places to start if you don't know what you're doing.
- Instructables had some circuits that are almost right, but have really bad advice on selecting your transistors and diodes. Or they had capacitor values that are out by factors of 1000. Breadboarding some of those circuits didn't work.
- There's a good summary that got me started at Sessionvile. Later I realised that they have copied all their circuits from other places though.
- In the end I found an article on Premier Guitar website that was perfect for beginners. It has a demo video, and detailed instructions in a PDF. This is the one that I ended up getting working.
All of the diodes, resistors and capacitors for this build came out of old electronics that I had sitting around. I basically went nuts with some pliers and a soldering iron, pulling likely components out of broken toys, old answering machines, etc. I think the only things I needed to buy were the transistor (used a PN100), and the potentiometers, jacks and switches. The only place I knew to buy electronics was Jaycar, which has an OK range, but I didn't know which transistor to buy so ended up with a generic one.
I started with a breadboard version, and experimented with different diodes for clipping. In the end I decided on a soft clip pair of diodes and a hard clip asymmetric trio, each controlled by a switch. The hard clip is three 1N914 diodes, and the soft clip has a 4001 diode in there, but I've got no idea what the other diode is - it came out of random bits of electronics and I don't know what the coloured markings mean. I also tried LEDs as the clipping diodes, but couldn't get much difference out of them.
I put a switch in to change the input capacitor between 100nF and 6.8nF, to vary the amount of bass cut.
Soldering was done onto a perma-proto board, because it meant I could simply move everything straight from the breadboard on to the PCB.
For the enclosure I used an old iPhone plastic packaging box. After putting it all together I then read about the benefits of a metal enclosure for cutting outside interference. With this pedal, if you touch the switches on the top you can hear the local radio stations through the amp. Not ideal!
[video width="640" height="360" m4v="http://graybloomfield.com/guitar/wp-content/uploads/2016/10/dist1.m4v"][/video]
The sound is not bad - I prefer the soft clip sound.
