Should be doable, I can't see why not. But I would recommend to simulate it in Spice first before building the circuit. In integrated design, scaling of currents is done via geometrical properties of the transistors and cross-matching. Which is something that isn't visible on a schematic like this, ...

Yes, at that point you can just take out the cap and resistor completely. To further reduce gain you can put in a series resistor with the 22µ on Q2 emitter or take it out as well. Like Belanger said increase the emitter resistor or increase the 47k in series with the potentiometer, which limits the...

It seems like you don't have a pulldown resistor in front of the input capacitor. Comparing with the original schematic, it isn't there as well. Just put a 1M from the cap to ground.

Maybe their reasoning was to avoid the electrolytic capacitor. The bigger resistors only require smaller capacitors, which allowed the use of film instead of electrolytic. That is the only possible reason I can think of. Not sure that is much of an advantage though. Any opamp will drive a couple of ...

Sure it will work. But why not strive for better?

Low input impedance. This will seriously load down the guitar pickup if it is directly connected and remove much of the harmonic content. If it's another pedal before it, chances are it will decrease the level a fair bit and decrease the SNR. Should be 500k-2M. Unused opamp half, this is bad practi...

That must be the worst design I've seen in quite a while. Thanks for posting anyway . How somebody can mess up even the simplest of circuits that bad is just mind-boggling.

Checked my photos, 50k linear is correct.

Manfred wrote:BTW, all drawn schematic found by tracing are copyright infringements too.
viewtopic.php?f=7&t=24020&start=20#p269820

No, they are not. It's your own artwork, you created it.

C10 should be at the junction of R8/R9, not at the opamp output. I won't argue that it should be, but I'm fairly certain that it wasn't. @marshmellow As long as C10 is in the Vref net, there's no big difference. Check the pics in page 1 of this thread. :thumbsup Placing a capacitor of that size on ...

bugg wrote:Traced from original, all SMD caps removed and measured.

CharlesEQ.jpg

Full schematic (and PCBs) available here:
http://www.pedalpcb.com/product/angrycharles/

C10 should be at the junction of R8/R9, not at the opamp output.

One remark: the MPSA18 isn't a darlington (like some of the other MPSAxx), it's a standard bipolar transistor.

See here: http://valvewizard.co.uk/smalltime.html Pin-6 of the PT2399 is a voltage source that rests at half the chip's supply voltage, which is provided by a 5V regulator in this case, so pin-6 will be at 2.5V. The current sucked out of this pin controls the delay time. An important thing to consid...

With the switch open the circuit is just a flat buffer, the frequency boost is disabled.

Borrowed this for an afternoon to take a look inside. Yet another 386 circuit, yawn... But it actually doesn't sound too bad over the whole gain range, still nothing to write home about though.

For reference, the Purple Plexi and the Black Magic.

Gyrator based equalizer.

The output volume should be well above unity gain if the pedal works correctly. Check the DC voltages on the JFETs first.

The first triode is just a standard gain stage, it is not part of the PI. So the part AC coupled seems to be important: you mean that plate1 is connected to grid2 trough a 22nF coupling cap, thereby blocking DC? Yes, that's what it means. A capacitor is used to block DC, hence only AC signals can pa...