Intro

Hi everyone! I had the chance to get my hands on the MXR Doubleshot for a little while, and found out there are no available schematics anywhere. It's nice to do some selfless circuit tracing once in a while, in the true spirit of FSB.
Starting from what was known already, the Doubleshot is usually described as the dual channel version of the Dime, and we'll see this is accurate. That circuit already has something interesting in its own right, but this one builds upon it with the...

Hi guys,
I was just reading a lot of topics and I'm looking for clues to repair my EHX Memory Boy.
It was stored for some years, and now i can't get any effect out of the pedal, i already tried battery, and AC, and the behavior its the same, i can turn it on and off, i have sound, but no effect...
Delay and Depht doesn't affect the sound and blend and feedback just do some type off modulation turning the sound imperceptible.

Anyone can help me with this one?

pls delete

Thought I'd pick up one of these to see what it's like.
I was hoping I'd be lucky and it would be a take on the Moen Shaky Jimi/Jimi Nova, which are based on the EasyVibe.
Here's links to the Moen Shaky Jimi and Moen Jimi Nova threads.
And I'd like to thank John Hollis for his lovely EasyVibe circuit. :thumbsup

What's inside then? The highlights:
1 x ST 064C
3 x TI TL062C
4 x LED/LDR pairs

It does indeed look to be generally based on the Moen/EasyVibe circuit although I haven't checked the...

Hello
Since high beta germaniums become so expensive Im searching for germanium transistors with low hfe and leakage. Do any of you know what russian models to search for??

Like like 1-10 hfe maybe at most 20
And 1-30ua leakage, the lower the better

Its for distortion pedals and the low leakage is the most critical since i use them in darlington configuration

I”’ve hade excellent results with af239 and a few other low leakage AFs with zero to 20ua leakage.

Sorry for my bad english

When I was in highschool in the mid-1990's, one of my bandmates got a brand new Turbo Rat. I was surprised to see that it didn't have the same kind of footswitch as my Rat 2 (also bought new around the same period, probably 1994). His Turbo Rat had a plastic soft touch footswitch like this:

I later saw this same style footswitch on my Roadkill. We now all know that the Brat/Roadkill used electronic FET switching like a Boss/DOD pedal. Now I'm very curious if there was a short-lived version of...

Radiopratica 1971_09 Camero Distortore.pdf

Radiopratica 1971_09 Camero Distortore 1.jpg Radiopratica 1971_09 Camero Distortore 2.jpg Radiopratica 1971_09 Camero Distortore 3.jpg Radiopratica 1971_09 Camero Distortore 4.jpg Radiopratica 1971_09 Camero Distortore 5.jpg

Figured I’d take a few pics of this before I let it to. Not a bad sounding unit at all. Darker than most pt2399s based delays I’ve used but it has a darker vintage analog delay tone “think dod FX90 or any old Reticon units pushed to their max. Modulation was also nice. Just have too many delays. Only changed I noticed with the chips is a tl072 used instead of a burr brown. Even has voltage regulator and preamp trim.

Tecnica Pratica 1965_12 Ampli transistore tremolo.pdf

Tecnica Pratica 1965_12 Ampli tra 01.jpg Tecnica Pratica 1965_12 Ampli transistore tremolo 02.jpg Tecnica Pratica 1965_12 Ampli transistore tremolo 03.jpg

Nothing much to see here with all the smd components. But I know others have been curious as well is this is just a crushing orange , bb pre, clone. It doesn’t sound like the bb preamp. Or, atleast the taper on the gain and level react differently. Isn’t near as loud as the crushing orange or bb pre either. All I could make out were the 2 TL072 op amps and 2 diodes d1 and d2. Maybe 1n914 or 4148s? Anyways I figured @cheapedalcollector may enjoy it.

Tecnica Pratica 1966_12 Tremolo.pdf

Tecnica Pratica 1966_12 Tremolo 01.jpg Tecnica Pratica 1966_12 Tremolo 02.jpg Tecnica Pratica 1966_12 Tremolo 03.jpg Tecnica Pratica 1966_12 Tremolo 04.jpg Tecnica Pratica 1966_12 Tremolo 05.jpg Tecnica Pratica 1966_12 Tremolo 06.jpg

PDF: Radiopratica 1968_11 Vibrato.pdf

Radiopratica 1968_11 Vibrato 02.jpg Radiopratica 1968_11 Vibrato 03.jpg Radiopratica 1968_11 Vibrato 04.jpg Radiopratica 1968_11 Vibrato 05.jpg Radiopratica 1968_11 Vibrato 06.jpg

I took a few shots of the TonoMatch ProTubeScreamer.
It is a high quality pedal in mechanical and electrical workmanship.
Jacks with gold-plated contacts.
True bypass with relay and electronic control.
Only film capacitors in the signal path.
TonoMatch 1.jpg
TonoMatch 2.jpg
TonoMatch 3.jpg

Hi,

We just released an open source, DIY tape echo you can build.

It's built using 3D printing and a cheap walkman style cassette player. Everything needed is free online (goto our website or our github page to get the files). There's some detailed build instructions on our website.

Be interested to see peoples builds!

r Vibrato April 1962.jpg

Hello all,
just to let you know, if like me you use eagle for pcb design and download a lot of footprints from snapeda. I noticed , already 2 errors:
1 the 2N5172 transistor footprint is wrong: EBC instead of ECB (the probably copied a generic 2NXXXX footprint)
2 I tried a 3 colors LED footprint, but when I open it on eagle the pads overlap...
So double check everything before making a PCB...

Cheers
Benoit

I continue to trace my Exar pedals - today, it's Exar KM-03 Kamikaze. That particular model seems to be quite popular in Poland back in time because I've seen some good mentions about it. I had two units; both had the same components inside, so I traced the one in a slightly worse condition. For another one, I have a box and user manual.

PXL_20230225_192446413.jpg
PXL_20230225_192518975.jpg
PXL_20230225_192529156.jpg

PCB is standard for Exar series 3. However, it uses two SMD ICs, which...

Does anyone know what exactly this does? He doesnt offer it anymore, so I assume it's fair game. I have one lying around that I want to do something with

I would appreciate any help troubleshooting this uni-vibe issue.

This is the uni-vibe with the vintage button. PCB UV-1 Main Board Rev. A July 10, 1997

Power supply is Dunlop ECB004US 18v
1 Amp.

Effects led briefly flashes as power supply is plugged in. Chorus/Vibrato led works as expected when activated but no effect because sw2 never activates.

Voltage regulator is ok. 18v in 15v out.
Effect switch has continuity when activated.
Ribbon cable from switch board to main board has...

Hi,
I received this pedal for repair. Totally not working.
Someone could help me with schematic?
Thank you!

I do quite a few pedal and amp repairs for a music shop so built a 1 kHz 2 transistor multivib signal generator with a 386 amplifier and a 3 inch speaker all in a re-purposed plastic box.

It works fine but the 1 kHz tone gets on your nerves after about 10 seconds so I started using my Strat as a sound source instead. This is not ideal as you have to keep strumming it and strummed open strings get old fast.

I then came across a set of sound samples that The G posted a couple of years ago and...

Hi guys I bought the Appetite for Distortion pedal from PCB Guitar Mania but it's barely making any sound.

I put the red LED backwards (facing up instead of down) so i removed it and i struggle to put it back the right way. I dont think this affects the sound though.

When the pedal is off, the signal is passed through cleanly. When it's on, i can hear the distortion, but it's super low output signal, i can barely hear it. I don't know where i went wrong.

Your help would be appreciated....

I wondered if I could swap the LED/LDR (or opto) for a FET, mosFET or 4049 gate (inspired by the PUP phaser series).

Here's the original:

I wanted to add a buffer, and that leaves me one opamp left on a quad, so I thought: What if I add dry non-inverted signal to the inverted filtered signal? The other frequencies should cancel out and the peaks should get peakier , right?

LTSpice kinda agrees:
( r being the resistance from point A and B to GND, where the opto is originally)

And a...

Hi,
I Have an MXR Analog Chorus that doesn't apply the effect:

- The original/dry sound passes trought the pedal, in both footswitch positions;
- Its a second hand Pedal;
- I don't have the diagram to troubleshoot;
- I disassembled the pedal and verified that the TP2 is missing, and instead, there is one resistor, with one leg in C16 and another led direct to one of the U3 pins;

I need some help trying to troubleshooting this. Sorry some english mistakes.

Hi all,

This is my first post here so let me know whether I am posting in the wrong section, or anything!

I was wondering whether anyone had success building Tim Escobedo's Q&D VCF, or a variant of it (I understand that the topology is an active bridge-T filter, so variants might be published elsewhere).

simplevcf_252_119.gif

I put the second version on a breadboard with my guitar at the input and a digital cab simulation pedal at the output and all I am getting is a nasty metallic...