The designer of this circuit, Eugene Zhernovoi, emailed me to tell me about his noise gate design, which as far as I know hasn't been introduced here at this forum. Looks interesting. The website is in Russian, but here is the schematic for it:
http://stellar.ho.ua/NoiseGate/Doc/NoiseGate.pdf
Looks very promising. Got a pcb layout by any chance?
Wow, you just gotta call it the KGB. That which quiets down that which one doesn't want to hear!
Quote from: tednet on November 25, 2009, 12:53:33 PM
Looks very promising. Got a pcb layout by any chance?
There is none that I know of.
How do you use it? The FX´s go in the send/receive jacks?
Quote from: Morocotopo on November 25, 2009, 04:51:35 PM
How do you use it? The FX´s go in the send/receive jacks?
I think that is the idea.
> How do you use it? The FX´s go in the send/receive jacks?
The send/receive jacks are convenience frills. You could omit them: Q1 Source to C16.
They ARE convenient when you have a hissy effect. This connection watches the guitar level. When guitar shuts-up, the gate shuts-up, even if the FX continues to hiss.
U1A and U2A is a HIGH-gain audio amp. So much gain that anything bigger than gitar-hiss will make Volts of signal. D1 U2B D2 make a DC voltage, C17 holds that voltage between cycles (and an adjustable bit more).
Q2 sits normally-"shorted", against R19 signal-resistor, muting the output.
Guitar signal swings C17 in a direction to un-"short" Q2, and signal passes R19.
Since the 220K R19 leaves a signal too weak to drive long cables, U1B buffers it to drive almost anything you'd find on a stage.
Layout and bypassing will be fussy. U1A U2A have HIGH gain and any sneakage around them will oscillate. When we did this job with a row of discrete transistors, we used a long narrow board and a separate power supply. Chips make it easier, but not a no-brainer.
There's nothing radical here. Study other noise-gate layouts for guidance, especially around the high-gain path from input to rectifier.
Quote from: sean k on November 25, 2009, 03:01:41 PM
Wow, you just gotta call it the KGB. That which quiets down that which one doesn't want to hear!
Perfect name. Mind if I use it if I build it?
No ownership on my part and it's just a suggestion so go ahead.
The man who designed it may not think the association is kosher and may prefer the FBI or CIA :icon_wink:
I figured this would be a good place for everyone to analyze the circuit and determine what its weaknesses might be. :icon_wink:
Quote from: sean k on November 26, 2009, 03:17:12 PM
No ownership on my part and it's just a suggestion so go ahead.
The man who designed it may not think the association is kosher and may prefer the FBI or CIA :icon_wink:
I'm in Canada. Closest we got is the RCMP. Maybe CSIS. Terrible names though.
KGB works good if you build a Russian Muff and whatever other Russian circuits we can think of. What do you think of assembling an all Russian cast for a pedalboard eh?!? Comrade?!?