Nobles ODR-1 switch glitch

[PBE6]

I just repaired a Nobles ODR-1 pedal for a friend, but I'm worried I may have screwed something else up along the way. For reference, here's the schematic:

So Q1 was the original culprit, I replaced the BC264D with a 2N5457 (which, as I discovered later, has the *opposite* pinout), and everything is back to normal. Everything works fine when I'm using a 9V battery (around 8.1 V now), but when I plug in the adapter the switch gets a glitch - when I try to switch the pedal off, the light flickers and then comes back on again. I forgot to measure the voltage from the adapter (duh), but I do remember it being around 10-11 V from an earlier project. I've read through GeoFEX's Technology of JFET Switching article a few times, but I still don't see how a higher supply voltage would impact the switching since we're just trying to pull the gate to ground.

Could it be that the switching chip shown in the bottom left of the diagram isn't happy with more than 9V?

Any help would be appreciated!

[PBE6]

BUMP

Anyone ever had problems with a JFET switching scheme with where it worked fine with a 9V battery but not so fine with higher DC power from a plug? Is there a general reason why this might happen?

[duck_arse]

interesting. this very day I spent all afternoon aimlessly fartarseing on the breadboard rigorously observing empirical evidence of the nature of a pnp-mosfet soft bypass fet switcher, one of transmogrifoxes designs. not messing with voltage changes, but I did find that different devices have different reliable working ranges of C for R.

in some cases, a switch of transistor would render an R/C set non-operational. they seem to have a fairly narrow window of C values that will work for a given R, and a too high value would give an odd blink of the led. (I can't see what's going on in that corner with the switching, is it just a single pushbutton?) the 4007 mosfets would be somewhat similar to the circuit I was fiddling, so it might be that the extra volts has shifted the range of good R/C's.

[PBE6]

Interesting! Good to know. That could indeed be the case here. I guess the easiest fix is to get a well-regulated power supply!

The switching on this pedal is just a single push button, very similar in looks (and function, I think) to the BOSS/Ibanez switching scheme. I've never used or seen a 14007 IC before, wasn't even sure I was reading the name right! (Sorry about the tiny image BTW, was all I could find.) I'll see if I can find a datasheet for it and check out their voltage range warnings.

[mcknib]

Here's a bigger zoomable schem might be useful:

http://experimentalistsanonymous.com/diy/Schematics/Distortion%20Boost%20and%20Overdrive/Nobels%20ODR-1.pdf

[PBE6]

Thanks!