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A client asked me if I'd ever heard the Roland GP8's phase shifter section. I hadn't, but I found a schematic and breadboarded one. It bares so similarity to the MXR Phase 100 in that it contains both variable and fixed phase shift stages. The Phase 100 uses LDRs and has 10 stages; the GP8...

I got a hold of one of these and had to trace it. It's a modified Silicon Fuzz Face, hand-crafted in the Czech Republic by Electronic Orange. Beautiful construction in a bullet-proof steel case. In the SINGLES position, C2 and the PU trim pot are bypassed. In the HBS position C2 & PU trim...

Here's the C3-PO parametric filter. Top view: 16 cuts 8 links, 4 on the bottom. For the bottom links, just bend over a lead to join 2 adjacent strips on the solder side. For example, the purple GND strips on the left.

This Vero layout is for the R2-D2 Opto-Face. Yeah, it is some Crazy Shit. Top View: 10 cuts 4 links - 2 on the top, two on the bottom. Bend D1-A over to join the two GND strips and bend the right-hand lead of R3 or R4 over to join the two pink power rail strips.

Back when I was a young lad, my friend & roommate Richard bought a Black Finger. As per usual, I would cajole him into letting me take it apart & trace the circuit with the the promise that he'd get it back intact. A very interesting circuit indeed. Years later he sold it to me and I still...

Another OD inspired by HamishR down under in Perth. His earlier versions had four JFETs and a different tone stack. I took one of the later versions, deleted a source-follower stage between the clipping diodes and FMV tone stack, fiddled with the EQ and clipping a bit and here's where I ended...

This pedal has received some rave reviews in the Build Reports forum, so I had to breadboard it and see what it was all about. The circuit starts out simple, with the first two stages looking pretty similar to the BluesBreaker. After that, there is a whole lotta EQ. At low GAIN settings, all...

Found this on PCBWay, designed by Glory to Ukraine. Based on the name, I half expected this to be a banjo pedal. This schematic is from the build docs. Most of it makes sense, although I fail to see the need for input and output buffers. I breadboarded it per the schematic, minus the input...

Guitar PCB offered this PCB as a bonus during a recent promotion. It's an interesting all-opamp version of the traditional BMP architecture. Note the diode soft-clipping on three stages, instead of the usual two. The gain is throttled in the 1st stage feedback loop, instead of between stages...

A very clever circuit and makes great tones right out of the box. It's sold as the Jump Drive here. The 2nd & 3rd stage use MOSFETs as asymmetric clippers. That's clever part #1. Looking at the 2nd stage (IC1.1), when the output (pin 1) swings positive, Q1's body diode conducts and the...

I built one of these a few years back and my only complaint is the hiss. I replaced the aluminum caps with tantalum and it helped, swapped out a couple of opamps, but none of it made much difference. With the GAIN & Tone turned up there was too much hiss. Other than that, it is a sweet...

This was inspired by Music6000. He sent me pix of a pedal he bought called the Canaglia and a link to a schematic on FSB. A simple circuit, 3 knobs, basically an Electra driving a SHO. I made a couple of improvements to how the GAIN & DRIVE pots are connected and here it is. This is a...

In this part, we'll discuss what happens when we put a resistor in parallel with a pot. We'll address the simple case where we use the pot as a variable resistor (as opposed to a variable divider) where we connect two pins together. The first example is a B-taper pot. We'll connect pins 1 & 2...

So how do know which taper to use? It really comes down to how the circuit responds when we turn the knob. For the most part, A-taper is good for GAIN and VOLUME knobs where we want to be able to easily access settings over the full range of rotation. Examples: The maximum output from a TS is...

There are a lot of misconceptions floating around regarding pot tapers and parallel resistors, so I thought I'd make an attempt to clarify things. I'll explain how to read the pot taper charts in the Alpha datasheet, how the circuits react to pot taper and resistance, how to select a pot taper...

HamishR emailed me a few days ago with a mod to the Eliminator (PPCB Recycler) OD. The Eliminator bears a strong resemblance to the M.I. Audio Crunch Box, with the LED clippers deleted. Missing Link added a Vref buffer & output buffer, both of which I consider unnecessary. HamishR added the...

This one has been in the queue for a loooooooooong time. I built it pretty much per the schematic I got from Robert. I subbed an MCP6002 for the MCP602, a CA3240 for the LM258, 1SS98 for the BAT48's and a 2N5246 for the 2K208-Y. The Shallow Water manual was helpful in setting the LPG trimmer...

I just can't get enough of Bjorn Juhl's pedals. There are two versions of the Blueberry pedal. V1.0 has the input feeding into U1. V1.5 has a JFET booster in front of U1. I breadboarded V1.5 with a few minor mods. I rewired the NATURE control as a BASS control and added a TREBLE control. I...

This is something that HamishR & II have been messing with for a few days. It's kind of an an outgrowth of the ChuckMeister. It started with HamishR taking the 1st half of the ChuckMeister (he call his version the Shredmaster) and stacking it with a circuit we call The Beast. Then we started...

This EQ pedal kicks ass. My breadboard is built pretty much per the build docs, but I subbed a few parts when I didn't have a few oddball values. A word of warning, this circuit does not take kindly to mods. Don't ask me how I know that. If I had to guess, this design is based on an earlier...