Piggyback Pair

Germanium transistors are becoming more and more scarce and the ones that you do find aren't great options for the classic fuzz circuits. If only there was a way to use silicon transistors, both cheap and readily available, to simulate/emulate germanium transistors. Well the Piggyback method of tying two silicon transistors together does exactly that. It also allows the gain of the end transistor to be dialed in via trim pot. There are a few pedals on the market that use this method to produce their tones but it's really not that common. Try it out.

Scream & Whisper

My take on one of the most famous pedals to ever be made, the Tube Screamer. I've added some quaint modifications and value changes and added a transistor based noise reduction circuit. The actual screamer side of things is based off my personal Hudson Electronics Sidecar pedal, he threw in some odd valued and unnecessary capacitors but otherwise its a solid pedal and my favorite derivative. The noise reduction circuit is a loose interpretation of the 'one knob noise gate' project from the DIY forums. I stacked my op amps but to be honest couldn't really tell the difference, but it's got that cool factor now so....... 

Optical True Bypass

 I found this one on FuzzDogUk's website. Its a neat way to use DPDT switches for true bypass and still get the indication LED. This is totally doable via the Millennium Bypass family of circuits but I just thought this was an easy project to do. Who doesn't like options.

 

Please Leave A Message After The Fuzz

The ISD1820 Record/Playback IC has seen a resurgence in use the last few years. MidFi Electronics released his Propaganda Machine, Parasit Studios Subspace, BASTL did a project, WRAA did a project, Casper Electronics has fucked around with them, and even I myself have made a few designs with the old girl. Here is a pretty gnarly fuzz I whipped up. The tone/filter control is pretty versatile and has a wide sweep. Something different than another boring transistor fuzz. Check out my other projects using this chip the 'Flooper' and the 'Always Remember To Never Forget".

 

Overprotective Parent (I'm 18 & Moving Out)

 Exact same circuit as the original but with the added onboard charge pump. Circuit will prevent damage from over voltage and is resettable/reusable over and over again. Refer to the original for more information. 

Overprotective Parent

 This is one of the coolest circuits I've been able to wrap my head around. An overvoltage and polarity  protection circuit that wont require the any parts to be changed or re-soldered due to misuse. The only pedals I've had to fix for people were broken because their "friend" accidentally plugged in the wrong power supply and fried some internal components. This little circuit will prevent those parts from getting fried, and will also save the hassle of having to repair it. What is commonly referred to as a 'crowbar circuit', it baffles me that this isn't more commonly implemented. 

Basic Math

Circuit consists of two transistor based drone oscillators tuned to different pitches. With a little experimenting and knowhow this could easily be turned into a working keyboard/piano. I'm pretty positive that this is how a lot of transistor organs function under the hood.