Jackson Audio Amp Mode

Here's Jackson Audio's MOSFET boost, the Amp Mode. Pretty simple MOSFET circuit with a BJT output buffer. Easy fit in a 1590B. 

Caroline Wave Cannon

 Here's a very cool Rat variant now out of production. Fairly straight forward Rat with a variation of the Ruetz Mod, LEDs for clipping and a switch to toggle a feedback loop. On the original this is a toggle (SPST), but would be fun to put on a momentary footswitch. Couldn't confirm the IC in the original, as the markings were painted over. Might be easy to assume the IC is an LM308 or OP07 since it's based on the Rat, but it's missing the compensator cap (30pF cap across pins 1-8 in a normal Rat) so I'm guessing a TL071/LM741, but an OP07 would work too. Fits nicely in a 1590B or 125B. Schematic here

Boss SG-1 Slow Gear

 The Slow Gear emulates a guitarist riding the volume pot or a volume pedal, creating a swell effect. This will fit comfortably in a 1590B or 125B, though with the 1590B you'll probably want to wire the pots off board or use long-leg right angle pots mounted on the component side. Here's the schematic for reference.

J. Rockett Tim Pierce Overdrive

 Thought this one was interesting so I gave it a go. It's a fairly typical Rockett overdrive (.45 Caliber, Animal, Blue Note, etc.) with a fairly typical MOSFET boost (AMZ Booster, EQD Black Eye, etc.). Fits in a 125B with dual footswitches. Schematic and discussion found here. Fabricated version available on the store.

Solid Gold FX Rosie

 Happy Fuzz Friday, all! Here's a cool silicon Tone Bender style fuzz from Solid Gold Fx. Aside from using silicon transistors, the first stage is a JFET. When the switch is closed it adds in a 4.7uF input cap in parallel with the 330pF input cap. You could replace the switch with a B100k pot (lug 1 to Sw1 pad, lugs 2-3 to Sw2 pad) to blend the two values. Set the trimmer to 4.5v for the JFET and adjust by ear as needed. 

EHX Small Clone

 The blog needs more modulation, so here's the classic EHX Small Clone chorus. Made famous by Kurt Cobain, the Small Clone has a wide range of chorus tones. I've laid it out two ways, one stock, and one with the Depth switch replaced with a pot. You can probably squeeze this into a 1590B, but I'd stick with a 125B if you want the board mounted to the pot(s). Schematic for reference.

Solid Gold FX Super Drive

 Here's an interesting take on the classic DOD 250/MXR Distortion + circuit. It's pushed by a simple BJT boost and has an added presence control and tone switch. Schematic here. Easy to fit in a 1590B or 125B.