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Ok, so I built this high octane Blues Driver for a friend, working on 18V using an ICL 7660 S CPAZ like in a Road Rage. So I get a phone call two days ago that his chorus pedal is making weird ticking noises in combination with it. I can best describe it as a birdlike chirping, like waking up on a nice spring morning. Cool yet undesired. I made a recording of it whilst fiddling the depth and speed knobs:

Recording

This happened with his DOD Super Stereo Chorus FX68 (sadly, no schematic is available, though there is one for the FX67) but not with an Arion Stereo Chorus SCH-1.

This is the schematic for the Blues Breaker:


Anyone ever experienced something similar or have any clues/tests/suggestions?

I use vinyl sticker for my graphics, they're very scratch resistant. I sometimes include the drill template in the artwork. Put on the sticker and drill on.

I've started drilling the holes a bit over sized so I have some room for adjustment. I convert the image to PDF, this helps a lot with the printing usually. Then I test fit everything together in Photoshop.

And it's working
Thanks all, on to the next version, not done with this thing.

You seem to be spot on oldhousescott. Adfding a cap there stops the whining. Now all that's left (hopefully) is to check it with guitar later this afternoon. Over at DIYSB someone suggested making it a split rail design. I have a few issues with the tone control as well. All in all, enough to do a little redesigning

More tests, more info: it seems pins 5 and 7 of the opamp are working as transmitters? I came close to them with an audio probe (not touching) and it picked up the sine wave through the air. I'm guessing this should set off alarm bells for someone with more electronics know how than me...

The first part of the circuit, up to C2 in my schematic has been confirmed to work properly.

Could it be that C2 at the input of the second opamp stage is the cause? Should I swap C2 and R6?

*Edit* Just checked the schematic of the Madbean King of Klones (also a BB type thing) and that suggests that the order of C2 and R6 shouldn't be an issue.

As a quick test, I clipped off the second half of the opamp and the oscillations went away. So my guess is that it's the second part that's oscillating, supported by the fact that the frequency is influenced by both the gain and the tone pot.

Ok, this is a bit of a long shot, but I'm hoping someone can help me out. I've been working on a modified Blues Breaker circuit, running on 18V, and designed a PCB for it that I had fabbed by OSH Park. I tried the circuit before hand on a bread board but it was oscillating, which I thought was caused by long wires to the IC. But I just fired up my prototype and it's oscillating as well.

I tried audioprobing the circuit and the oscillation is all through the circuit, the pitch responds to turning any of the controls. Interestingly, I got the loudest sine tone when touching the input jack, so I suspect that something is going wrong right in the beginning of the circuit. This is supported by the IC voltages:

Pin 1: 9V
Pin 2: 9V
Pin 3: 8V
Pin 4: 0V
Pin 5: 9V
Pin 6: 9V
Pin 7: 9V
Pin 8: 18V

Notice Pin 3 with a 1V drop compared to the others. I'd expect 9V there?

I really don't know what to look for. Everything seems to be connected properly as far as I can tell with my DMM. I checked the schematic that I made to the one at GGG and the Morning Glory project, and I don't see any faults (but may of course be wrong). Any and all suggestions welcome.

Schematic


Board

Sound like it's not a problem with the diodes...check all your solder joints, audio probe the circuit, see where it's going wrong (probably in the first opamp stage).

Wow! That faceplate is absolutely gorgeous! I'd almost ask if I could order one from you Care to share how you did it?

Bought an Ampmaker.com kit last year. Very happy with it.

Very pretty, Stevie!

I still have more blisters from occasionally playing bass (plectrums suck with bass) than from soldering. Most of the soldering burns happen not during soldering, but during DEsoldering actually. I try to wear gloves (when drilling), goggles (when soldering) and ear plugs (when drilling holes larger than 1 cm) as much as possible. Most severe injury to a finger happened when an exacto knife slipped while trying to cut the plastic wire that was holding a pair of socks together. You can't see it anymore, but the tip of my thumb came right off (pasted it back and over the coarse of a few weeks it healed perfectly).

Grace Potter - The Lion The Beast The Beat
Avantasia (saw their show live last week, A-Ma-Zing, Kiske for president)
At The Gates - Slaughter of the Soul

And I just got tickets for both The Black Crowes and The Rival Sons

Covering all bases as you can see

@DutchMF: for an example of the sticker method, check my entry for the February contest (Spartan Overdrive). The guy usually ships the next day. Best to use a pdf of your picture and mail him the exact measurements. It does limit your choice of box colors to the lighter shades (or bare aluminum, which looks rather good).

Any Dutch people here know a good screen printing or laser engraving place? Anybody thinking of setting up a DIY rig? My house is to small to do it, but I'd love to develop a good alternative for small batches.