Problems Buliding Gaines Noise Gate. [With Pictures]

[NBguitarist]

Hey guys so I have just finished my Gaines Noise Gate build today however I found that it is not working properly.
Here is the PDF file for this project : http://hammer.ampage.org/files/GainesNoiseGate.PDF

I plug in everything and my Noise Gate is not taking any effect as if the signal is bypassed ( Yes I am sure the signal is going through the circuit ). Only the ATTEN. pot is taking effect on the volume.

Here is my work:







I following the test as suggest by the pdf file however I am not be able to get the target voltage on certain pins. (see picture below)











My question is here:

1. Why the GND pad of this circuit is not directly contact to the V-?  
2. While the GND pad is not directly contact to the V-. Why we should expected to see the those pin have the exact same voltage with the supply voltage (since the voltage should drop by certain component) ?
3. What I am doing wrong with my work?

Sorry I am completely new to DIYing pedal and I am not familiar with electronic so it is almost impossible to figure out the problem by myself. However I tried my best to show you guys my works as clear as possible so hopefully someone here can help me with my problem. If you need any further info to help determining the problem I will be glad to provide them as well. Sorryfor my poor english

Best Regrads.

[Fender3D]

1. Why the GND pad of this circuit is not directly contact to the V-?

Because here you need a dual supply

2. While the GND pad is not directly contact to the V-. Why we should expected to see the those pin have the exact same voltage with the supply voltage (since the voltage should drop by certain component) ?

3. What I am doing wrong with my work?

You need a power supply with 3 wires:
1) +V
2) GND
3) -V

Where GND is 15V under +V and 15V over -V

page 33:

"you can run this project from any standard +- power supply....
... Attach the positive power supply lead to the pad marked V+, the negative supply lead to the pad marked -V and the power supply common to the copper ... near the word GND"

[NBguitarist]

"you can run this project from any standard +- power supply....
... Attach the positive power supply lead to the pad marked V+, the negative supply lead to the pad marked -V and the power supply common to the copper ... near the word GND"

So should I apply this change to my circuit? Many thanks.

[Noise_Ninja]

So should I apply this change to my circuit?

No don't do that, you will pull the -15V to ground. you need a power supply with +15V, -15V and ground.

you need something like this:


but if your country uses 110V AC you need a transformer from 110V to 12V.

[Fender3D]

^^
NO

please start here http://www.geofex.com/Article_Folders/How_It_Works/hiw.htm

then google "dual power supply" and read everything about it...

[Mark Hammer]

This project was intended for home studio uses, so the assumption was that it would be in a rack-mount or half-rack chassis, rather than a stompbox.

You could implement a power transformer , as suggested by others.  What you might want to consider, though, is simply using a pair of battery clips for 6 or 8 AA batteries.  They don't take up an enormous amount of room, and if the goal is to aim for least noise, well, you'll never get LESS 60hz ripple than when using an absolutely pure DC supply from batteries.  If you go this route, you will need a DPDT switch (toggle or slide or rocker) to turn the power off and on.

[NBguitarist]

Thanks for your help. I finally got a dual supply by using two 15v dc supply. However still I am not be able to get my circuit working. It is not not taking any effect as if the signal is bypassed ( Yes I am sure the signal is going through the circuit ). Only the ATTEN. pot is taking effect on the volume. Any way to debug it? Thanks

[Mark Hammer]

Are you certain you have the JFET pinouts correctly identified?

[NBguitarist]

yes, i use the exact same fet as pdf suggested and I insert the fet according to the layout diagram.

[Mark Hammer]

Well, just to check off this particular box from the list of possibilities, I can confirm that years ago I built one from the layout in the article, and it worked exactly as intended.

HOWEVER...looking over the article again, I now realize that it used a piece of unobtainium: a TL075 quad op-amp, which is NOT the same pinout as a TL074.  It is a quad op-amp with the same pinout as an LM/RC/XR4136 - something that only a few of us tend to have in our parts bins.

Did you use a 4136 or did you attempt to use a TL064/74/84/LM324?  Note that the circuit will certainly work with a TL074; you just can't use Gaines' PCB layout.

[NBguitarist]

Hi Mark I am using TL075 (I can get this chip in my country with high price). I know the layout is working because I saw someone else built one with this. I later on find a error on my PCB board. I short pin 2 of TL075 to V-. Although it is now fixed and I can get a targeted voltage on certain pins of each IC. But still I am not be able to get my circuit working.

[moosapotamus]

I'm not sure exactly what you mean by...

It is not not taking any effect as if the signal is bypassed...

I'm probably misunderstanding, but a noise gate is not supposed to give you a bypassed signal. It is supposed to give you silence when you stop playing.

I also recently built the GNG and, while I found it to be kind of quirky, it did suppress low level noise, and the key input also worked to open/close the gate.

I tested mine by plugging a guitar into a noisy ring modulator pedal that had a significant amount of carrier bleed-thru, then plugging the ring modulator into the GNG. When playing the guitar, I got the ring modulator sound and, when I stopped playing, the GNG suppressed (gated) the carrier bleed-thru and I got silence, which is exactly what a noise gate is supposed to do.

What kind of noise are you trying to gate or suppress?

What instrument, effect(s), etc... have you plugged into the noise gate circuit, and what exactly are you expecting the noise gate circuit to do?

~ Charlie

[mistahead]

Get another box that has a bit of hiss in it, plug guitar into that box, then the Noise Gate, then the amp.

Back the noise gate way back and listen for the hiss, push the gate back up and see if it "cuts it off" the hiss (haven't bothered looking at how this one gates noise sorry).

I think you might have something moosey.

[Roger Martin]

Frustrating, eh ?
I once studied this Gaines noise gate.
In the end i decided naaaah...this is an ancient technology for such noisy pedals sold around the market today.

[moosapotamus]

I think you might have something moosey.

What?!?! It's not contagious, is it?

~ Charlie

[Mark Hammer]

I am almost embarrassed to be asking this question so late in the game.  This unit assumes a line-level input, so the sensitivity of the envelope follower and the range of turn-on thresholds is based around the expected range of signal amplitude.  If a person feed a guitar directly into it, the unit will not likely be sensitive enough to turn on.

I would suggest a few things, here, if this is the case.  First, try using it with a clean booster (e.g., LPB-1, MOsFet Booster, etc.) to confirm that the problem IS a question of mismatch between threshold and signal level, rather than a construction error.  The signal level may still be somewhat lower than the design expects, but with the threshold set low, and your booster set high, you should be able to turn the gate on when you pick hard (make sure to set the attack quick and release long).

Now that I am reminded of it, I seem to recall that in the exchange of letters to the magazine in the months after the article was published, Jon suggested chages to the values of R7, R10, and R11 to arrive at a range of voltages so that comparator A (that op-amp section) could be made to trigger in response to typical guitar range.  I wish I had saved those issues or at least photocopied the pages.  Unfortunately, I don't remember the recommended values.

Another possibility is to add some gain to the op-amp stage marked C.  If you put a 22k in the feedback loop and a 1k from the inverting pin to ground, I would imagine the level would be brought up high enough that the existing threshold range will work.

[moosapotamus]

Wow! Thanks for pointing that out, Mark. I don't know why I never realized that the GNG was intended for line level input. No wonder I thought it was quirky! I should probably dig it out and try making some tweaks.

Thanks
~ Charlie

[Mark Hammer]

I guess the name of the magazine it came from - Modern Recording - was not an obvious tip to very many, including, it would seem, myself.  If it's a recording studio, then the working assumption is line levels.

[DGAXEMAN]

you need 2 9v batterys one has red wire to ground black to minus v. the other, black wire to ground red to positive v also the
resister r27 does not go to ground according to the schematic but goes to r9 dont know why the pcb has it going to ground this may be a problem

[DGAXEMAN]

dont know why you have 5 caps in a row at the ATTACK POT SHOWN AS C1 there is only 1- 0.35uf there. built one and it works R27 GOES TO R9 TO PIN
1 OF THE THRESHOLD POT AND NOT GROUND.