Pedal-Pi is a lo-fi programmable guitar pedal that works with the Raspberry Pi ZERO Board. The project is totally Open Source & Open Hardware and made for hackers, programmers and musicians that want to experiment with sounds and learn about digital audio. 

You can code your own effects using standard C and get inspiration from the ready-to-use effects from the forum, like the Clean/Transparent, Booster/Volume, Distortion, Fuzz, Delay, Echo, Octaver, Reverb, Tremolo, Looper, etc.

The project was created with the aim of having fun and learning about guitar pedals. If you want to program digital audio effects in C without deep knowledge on DSP languages or electronics, this pedal is for you. But take also into consideration that it is only 12 bits and does not feel like a finished pedal that you could buy in a shop. 

The MXR 102 Dyna Comp is a compressor effect guitar pedal, released in 1972 by MXR and rapidly becoming popular because of its price and ease of use. The electronic circuit was also used as a reference design on many other compressor effects like the Ross Compressor, T-Rex CompNova, Ibanez/Maxon CP5/CP9/CP10 and boutique pedals. This model is neither the most silent nor the most hi definition piece of gear but it has real character and its easy to find.

This pedal produces dynamic range compression, this is basically smooth out volume differences between notes; giving more body and level to weak notes so the sound does not change drastically no matter what the real signal level is, giving better articulation and sustain to the guitar. The pedal also adds its own colouring and tone to the signal.

pedalSHIELD UNO is a lo-fi programmable guitar pedal that works with the Arduino UNO / Genuino UNO Board. The project is Open Source & Open Hardware and aimed for guitarists, hackers and programmers that want to learn about digital signal processing, effects, synthesizers and experiment without deep knowledge on DSP, electronics or hardcore programming.

You can program your own effects in C/C++ or get inspired using the ready-to-play effects from the online forum.

The Boss DS-1 is a distortion guitar pedal released in 1978 by Boss. It was the first distortion pedal made by Boss with a distinctive hard-clipping sound perfect for high gain rock and metal still keeping the character of the original guitar. The Boss DS-1 together with the TubeScreamer and the ProCo Rat cover almost all the spectrum of tastes for vintage classic rock/hard rock guitar distortion.

Referring to the electronic design, the current Boss DS-1 has a simple circuit: some transistor stages with an op-amp core and hard clipping diodes. This analysis is focused in the latest pedal schematic revision which is easy to find and prone to modifications.

1Wamp is a one Watt small guitar amplifier based on a JFET guitar pre-amp, the Big Muff Pi tone control and the LM386 power amplifier. This portable amp is an open hardware project designed by ElectroSmash using only free and open-source tools.

The preamp stage with two J201 transistors is designed to give a tube-like sound, the BMP tone stage is able to produce a big range of tones and the LM386 output stage can drive any kind of speaker, from headphones to a Marshall 2x12 cabinet.

Don Morris  is an electronic engineer who joined MXR's Engineering Team back in the spring of 1979. This is a short interview about how he worked on the Phase 90 redesign, the insides of the company at that time and his own story.

The Fuzz Face is a distortion guitar pedal designed in London by Arbitrer Electronics Ltd in the autumn of 1966. It produces a characteristic high distorted sound called fuzz.
Ivor Arbiter took the round shaped enclosure idea from a microphone stand and it was the first pedal including a DPDT stomp-switch. The effect became very popular because Jimi Hendrix played it and there were not many distortion pedals around at that time.

The gist of the Fuzz Face remains in the simple circuit that uses eleven components (2 transistors, 4 resistors, 3 caps and 2 pots) and the astonishing tones created with them; delivering a soft asymmetrical clipping that changes to hard clipping in both semi-cycles under the fuzz pot action.

Arbitrer Electronics manufactured the pedal from 1966 to 1975, Dallas Music Industries did a final batch in 1975-77, after that the production stopped. During its lifetime the pedal went through some minor cosmetic but major sonic changes. The fuzz face was re-issued from 1986 to 2000. In 1993 Dunlop took over the production selling the fuzz face in different flavors. Today, both the Dallas Arbiter and Fuzz Face trademarks are owned by Dunlop Manufacturing Inc.

This analysis covers the first Arbitrer Fuzz Face model equipped with PNP germanium transistors from the first releases which is considered the best sounding.

The Dunlop Crybaby is a Wah-Wah pedal released around 1982. The pedal is a copy of the original VOX model made by VOX/Thomas Organ Co in 1970. The effect is basically a band pass filter, it boosts the resonant frequency around 750Hz attenuating above and below harmonics. The rocketing action of the pedal shifts the resonant frequency up and down.

Due to the great success of the pedal, being maybe the most sold guitar pedal of all times, Dunlop produced several versions of the Wah-Wah and signature models adding enclosure customization and small circuit modifications. This study is focused in the first model, the Dunlop Crybaby GCB-95 which is considered to have the classic wah tone.