Anyone have a simple noise gate build?

[moosapotamus]

I think I found a discrepancy between the schematic and PCB for the Gaines Noise Gate.

In the schematic, R9 and R27 are tied together. But in the PCB, instead of being tied together, it looks like they both go down to ground.

In the overlay I posted (above), R9 is near the bottom center of the layout, between C1 and R10. R27 is directly below IC2.

My gut says to modify the PCB and go with the schematic. Yes/no?

~ Charlie

[Brymus]

I think I found a discrepancy between the schematic and PCB for the Gaines Noise Gate.

In the schematic, R9 and R27 are tied together. But in the PCB, instead of being tied together, it looks like they both go down to ground.

In the overlay I posted (above), R9 is near the bottom center of the layout, between C1 and R10. R27 is directly below IC2.

My gut says to modify the PCB and go with the schematic. Yes/no?

~ Charlie

Thanks for doing the overlay thats what I wanted to do ,but couldnt figure it out in Gimp.
And I think your right,I see what appears to be another problem based on what you already found.
I am going to evaluate it more and post back.
Thanks for catching that,Bryan

[Brymus]

Here look at this, I think this will fix R9, R27, and C1 by tweaking a few traces and adding two jumpers.
But someone else should look it over >The red lines are where the new jumpers would go.
I also cleaned it up even more,so hopefully this will provide a good sharp transfer if its all correct.

[Brymus]

This one is easier to understand >

[moosapotamus]

Bryan - Do you have larger images? I think I see what you are doing, but It's kind of small. What was wrong with C1?

FYI - I am working on redoing the whole layout for a couple of reasons...
1) Needs a bipolar power supply, so I'm going to add a +/-15V supply that will run off of a standard +9VDC power supply.
2) The specified dual opamp is TL075 (that's not a typo). Obsolete and not pin for pin compatible with TL074, so rerouting.
3) Flipping the footprints for the pots around to allow PCB mounted pots that will orient up and fit, 4 across, in a 1590BB.

~ Charlie

[Brymus]

Yeah I have the Gimp files if you want them,send me a PM with E-mail info.
Personally, I would rather just use what you draw up as you have WAY more experience at this than me 
I doubt I will use PCB mounted pots as I dont trust my precision, but I can just hand wire to the pads.

C1 was connected to R9 on the PCB and in the schematic it wasnt.Was I correct to unconnect it from R9 ?
Or was I looking at the PCB image wrong ?
thanks for the help,Bryan

[moosapotamus]

Okay, I see. You got it right. C1 goes to ground, it doesn't connect to R9.

I think I've got the layout reworked to use a pair of dual opamps instead of the weird TL075 quad. Now I just need to squeeze in the bipolar power supply. I'll post it when it's done.

~ Charlie

[~arph]

The Q & D compressor 2 uses the SSM2166 ic (smallbear has them, about $8)

That ic has a downward expander inside. If you build the Q & D compressor with a compression ration of 1:1 (no compression) you have a noise gate.

Low parts count too..

http://www.muzique.com/ssm2166.htm

[Mark Hammer]

The Q & D compressor 2 uses the SSM2166 ic (smallbear has them, about $8)

That ic has a downward expander inside. If you build the Q & D compressor with a compression ration of 1:1 (no compression) you have a noise gate.
Low parts count too..
http://www.muzique.com/ssm2166.htm

The downward expansion is one of my favourite parts of the Q&D.  Cures the perennial complaint of compressor-users: "Why is my compressor so noisy?".  And while the chip itself is not exactly a 25-cent op-amp, so few additional parts are needed to make it useful that you can still have yourself a great compressor/noise-reduction system for under $15 (minus the chassis, stompswitch, etc.)

I know that HUSH chips were produced by SSM.  Can they be purchased by "mere mortals" at all?  http://www.zmitac.aei.polsl.pl/Electronics_Firm_Docs/Analog_pdf/ssm2000.pdf

[~arph]

Soon I'll be able to comment on the SSM2166, they are now somewhere over the ocean between the USA and Amsterdam.
I need to do some downward expansion after four PT2399's in series. The inter stage filtering is insufficient. I was really happy when I found this little chip. Haven't seen many downward only expanders, let alone simple ones.

I'll have to experiment with putting the expander in front and a filter at the end. Or the other way around.

You can see that it's prone to noise..though still surprisingly quiet 

[~arph]

I know that HUSH chips were produced by SSM.  Can they be purchased by "mere mortals" at all?  http://www.zmitac.aei.polsl.pl/Electronics_Firm_Docs/Analog_pdf/ssm2000.pdf

There is one on ebay for twentyfive bucks..

[El Heisenberg]

I might actually want a noise gate for drums. I'm a drummer and when I have my buddies over and we mic my kit there re some issues.The simple one posted by moosapotamus, would this work alright for that?


There's so many noise gates here now, I dunno which to commit to!

[Mark Hammer]

Arnoud,

The LM1894 is still available as far as I know, and is much cheaper than the SSM2166 and HUSH chips.  It provides single-ended "noise-filtering", with 2 channels on a single DIP.  http://www.nalanda.nitc.ac.in/industry/appnotes/Natsemi/AN-390.pdf

[~arph]

Thanks Mark,

I've seen that one too.. Interesting one as well. Needs little more signal conditioning at the front. Couldn't find supplier though. And I kinda like the fact that the SSM2166 can compress too. (found the ssm for about 4,95 euros now too ). Might try that one someday too.

[moosapotamus]

I might actually want a noise gate for drums. I'm a drummer and when I have my buddies over and we mic my kit there re some issues.The simple one posted by moosapotamus, would this work alright for that?


There's so many noise gates here now, I dunno which to commit to!

I would not recommend "committing" to that simple one that I posted unless you breadboard it first and confirm that it works well, or can be tweaked to work well for you.

And then another option that appears to have gotten some rave reviews is the single-knobbed DOD230. I believe scheme and layouts have been posted in other threads here, as well as at FSB, so should be able to search it up pretty easily.

~ Charlie

[moosapotamus]

DOD230

[Nasse]

http://i837.photobucket.com/albums/zz293/Nasse2/simplex1.jpg

I was shovelling dust off of some of my "archives" and found one paper I have saved. Perhaps not on topic but perhaps it is useful for something. Never tested it. It might be nice on drums or something. Small component count but dual supply and perhaps not for everything

[El Heisenberg]

The DOD230? They made another noise gate? I know they had the DODfx30 and DODfx30b which are really different from each other...


great now MORE noise gates to choose from! That percussion noise gate would be cool.

[moosapotamus]

For anyone interested in building the Gaines Noise Gate, I reworked the layout to replace the TL075 quad with a pair of TL072 duals. I also made two different power supply versions. The article references +/-15V for the circuit, so I did one layout with a 5V regulator and a 5-15V DC-DC converter to make +/-15V. But the DC-DC converter is a bit pricey and can sometimes be difficult to find. So I did another layout and replaced it with a LT1054 to supply +/-9V. My guess is that would give plenty of headroom for guitar playing. I have not built this yet, so both layouts are not verified.





The board dimensions are 3" x 1.8". Should fit nicely in a 1590BB.

Let me know if anyone finds any mistakes. Also if anyone wants to give it a go and wants a PCB transfer image, let me know and I'll post them, too.

~ Charlie

[El Heisenberg]

I gotta ask, what's "key in"?