DOD 230 Noise Gate

DOD 230 Noise Gate

Project description

A true vintage noise gate!


Well, I guess this layout isn't very true to the original design. The original had a TL022 and an LM358 dual opamp which I replaced by the TL074 quad opamp.

The original also had a now obsolete CLM50 optocoupler, which I replaced with the VTL5C10 (D1) as suggested by "Foo Zen Trader". A LED/LDR combination will work too, but may require some tweaking of R14 to get unity gain when the gate is open.

R21 is added as a pulldown resistor in case you want to true bypass it.

Verification status

I have yet to build this, so it's marked as unverified!


I boosted the input signal by changing R1 to 1M which gave me a better control over the gate. You may need to lower R4 to 110K if the gate won't close at all...

You can also use standard true bypass switching instead of the 'open gate' switch SW1.

Bill of materials

R1: 10K
R2: 10K
R3: 470K
R4: 220K
R5: 220K
R6: 22K
R7: 22K
R8: 22K
R9: 47K
R10: 100R
R11: 1M
R12: 1M
R13: 1M
R14: 10K
R15: 1M
R21: 1M
R20: 500K Log (A)
C1: 10nF
C2: 100nF
C3: 100nF
C6: 120pF
C10: 100nF
C4: 1μF
C5: 4.7μF
C7: 10μF
IC1: TL074
D1: 5mm
Q1: 2N3904
6 jumper wires
15 trace cuts


Click here to see the bill-of-materials as a list or download it as a comma separated values file (.csv).


BB Forum code
HTML code



Here is a discussion on how to get this to work:
No success yet...

What is D1 supposed to be?

I'm pretty excited about this one, I've been having some trouble getting the Tonepad MXR Noise Gate working, so this might save the day :)

One little thing though: The description talks about a VTL5C10 or a LED/LDR combination... but the BOM and the actual layout doesn't mention them at all.

What do I need to do?
Thanks! :)

verified - increase sensitivity?

This definitely works, and fits into a 1590A case :)

I used your mods R1 = 1M, R4 = 110k (actually have a 100k in there now)

The pot is most useful between 4 and 5 o'clock, and 5 o'clock is maxed.

I'm still kinda new to this, any suggested mods to get even more use of the range of the pot? Guessing bumping R4 might have something to do with it? Seems like having a lower value pot would make it more useful?

Appreciate any ideas!

thanks :)

Add a comment