I've seen this interesting noise gate made by Adiel here: http://www.diystompboxes.com/smfforum/index.php?topic=116919.msg1103734#msg1103734, and after some Googleing I found schematic and some PCB on Brazilian board, here: http://www.handmades.com.br/forum/index.php?topic=9870.0
Build was a success, it started working immediately, but soon I've noticed some problems. First of all, it had a nasty habit of tremolo-like decay, second, it worked very strange with bass. So I decided to improve it a little, and this is the result:
(http://i64.tinypic.com/2i9nx3n.jpg)
I've changed C4, R11, R2 and Sensitivity pot, added Decay pot and removed swell switch.
This is the finalized pedal:
(http://i63.tinypic.com/ipp2bt.jpg)
Did you try any other transistors?
No, why? I believe you can use almost any NPN, only use low noise NPN for input buffer.
PCB for anyone interested to build this, I hope it will fit in 1590A :icon_lol:
(http://i64.tinypic.com/dg31wm.jpg)
C4 and C5 are back to front. your drawing.
Well Heres what I've made of it so far on the breadboard.
Subs
All jellybeans used are 2N5088.
Some value are changed arbitrarily depending on what was left over in the breadboard parts box.
I didnt like the way your decay pot futzed with the transistor.
So I removed it.
I added a 10k (Attack) resistor R17 (my drawing)this changed the time constant and made the transistor on/ off smoother.
I'm guessing this is what you were trying to achieve with your decay pot.
You can futz with this some more if you wish.
Maybe a series R + Attack pot wired as a varable resistor in the place of R17.
Maybe 1k+B10k pot?
You note that I've also tried some different values for C12 (mine) this had a similar effect to the new R17, ie changing the time constant as before.
I made a switchable swell feature (with two swell times) similar to that seen in the designers drawing.
I also added a noiseless biasing network for the op amp rather than the one the designer used (2x 100k)
Probably futile and a waste of parts on my behalf, but I'm happy with it.
I've no doubt I could have biased the Q1 with it, but it's not really saving any parts.
(https://i.imgur.com/EcH0t2L.png)
Rich
It is quite a noisy circit too.
I forgot I swapped out the sens pot to a B1M.
Quote from: Kipper4 on January 30, 2018, 11:01:13 AM
C4 and C5 are back to front. your drawing.
That's how my drawing app shows capacitors, those two are not electrolytic, so it is not important how are they rotated.
Quote from: Kipper4 on January 30, 2018, 11:01:13 AM
I didnt like the way your decay pot futzed with the transistor.
So I removed it.
I had probably the same problem without it - vibrato style decay :)
Quote from: Kipper4 on January 30, 2018, 11:01:13 AM
I added a 10k (Attack) resistor R17 (my drawing)this changed the time constant and made the transistor on/ off smoother.
I'm guessing this is what you were trying to achieve with your decay pot.
You can futz with this some more if you wish.
Maybe a series R + Attack pot wired as a varable resistor in the place of R17.
Maybe 1k+B10k pot?
Interesting, I'll try that too.
What it the effect of that swell? I can't remember how it sounded, but I presume I didn't like it or thought that it is affecting decay stability, so removed it. It was one month ago, and I can't remember :(
Quote from: Kipper4 on January 30, 2018, 11:14:24 AM
It is quite a noisy circit too.
I forgot I swapped out the sens pot to a B1M.
Interesting, I didn't find it noisy at all? Maybe using BC550 for buffer is really that important?
Looks like you left the swell cap ,22uf on the drawing......
Also is R2 really 100 Ohms.
Yes, I left one of those swell caps, can't remember what happened when using another one? According to LTspice, it shall affect attack?
I made R2 100 Ohms beacause it seemed to work the best, at least in simulator.
I've also changed R16 to 10k to have less noise. Also, C11 should be at least 1u, for better low freq response.
If I remember well, this combination of R14/C6 was necessary to have LED indicator working well.
You can find LTspice file of this gate here: http://www.cad.rs/d/AQR-Noise-Gate.asc
Quote from: rankot on January 30, 2018, 01:30:56 PM
Interesting, I didn't find it noisy at all? Maybe using BC550 for buffer is really that important?
Yes, the BC550 is an ultra low noise device. That's why I recommend using it.
Quote from: rankot on January 30, 2018, 03:18:52 PM
I've also changed R16 to 10k to have less noise. Also, C11 should be at least 1u, for better low freq response.
1uF for C11 might change the time response, as well. My intention was to provide a simple circuit to suit my needs, not having to resort to rare or expensive components.
I am really glad and honoured it may serve others, and I am going to try all of your nice suggestions here, as soon as I have some free time.
And Rankot, the pedal and the layout are great, congratulations! I am flattered!
https://youtu.be/m4G_WlM37U8
I've been having breadboard problems hence the distortion. It's been a lot worse off camera.
I now have a functioning gate/sweller on the breadboard.
Thanks firstly to Adiel for the design and share.
I've made a few changes I hope you don't mind.
To better suit the swellers needs. Ie having a degree of control over the gate shutting.
So I added a few features, renamed a few, even added an untested decay mod.
R13 (below) is new. Still not sure of its usefulness until i scope this.
I tried 100k,220k. no go
560k that worked so I went 1M as I say I'd rather see the results before I'll commit.
The addition of the "sens" (envelope gain) just gives a bit more control over the gate shutting, not so Important when swelling long sweeping chords but for the fiddly diddly stuff we need a gate shut to order.
The two swell caps on the switch are for long chord swells 22uf
and short swell 4u7.
I wouldnt bother going much above 22nf for the envelope charge cap C5 (below)
I added a small cap to the envelopes NFB too.
Some voltages included
Thank you both great thread.
Edit. Erratta. theres a 1uf NP cap missing between gate pot wiper and Non inverting input.
(https://i.imgur.com/Ro8L8zb.png)
Heres an updated drawing with side chain.
C4 is bigger. Thanks for the advice Stephen.
The side chain may need a series 100k + series diode on the input depending on the signal fed.
(https://i.imgur.com/9rVXMEm.png)
Just to ask - why've you removed gating indicator LED?
I figured it would be pretty moot on the breadboard.
A distraction. I'll probably try it before I think of doing a layout.
Did you find any of my findings useful.
I tried a few send return effects and that would need some more tweaking.
As would a key input, you never know what someone's gonna plug into it.
I was pretty interested in the swell feature
It's just a shame the amp has some distortion and noise.
It does some nice long chord swells to short note swells.
Bonus is, it's a fair gate too.
Kipper4, thanks a lot for the nice ideas. When I tried C4 (last schematic diagram) at 10n, the gate seemed to take too long to close, letting some noise pass through. That's why I settled for 2n2.
The 3-position switch is a clever touch, I did not have a small enough switch at the time, to fit in a 1590LB...
External triggering reminds me of the Gator, from Craig Anderton. Great idea!
Kipper4, I have already boxed my gate, so I am kind of lazy at the moment to experiment (really hate unboxing and boxing again), so why don't you try to add 1M pot instead of swell switch and use only one 22u capacitor? How would it work?
Rankot I tried a 1M pot to Gnd // with the 22uf and I was not of much use. Not worthless either.
Depending on playing dynamics and note/chord lengths i can mostly get what I want without the extra pot.
I've settled on a version without the key input or send/return loop.
2 knobs 1 switch should squeeze nicely into a 1590b.
Currently doing a perf build.
My first in a month or so. It's been all learning and modifiying for a while.
Tonight I get to inhale the sweet smell of solder flux.
If I come back in the morning asking for debug tips.... Just run :)
Great little circuit Adiel thanks.
Rich
Only two problems. Envelope ripple and thump when the shunt opens.
Grrrr
Ripple was the reason why I have changed all those things...
Can you elaborate please. I'm struggling to see how the decay pot works.
I am not sure, I built it first to original schematic, then noticed ripple at decay. Maybe I forgot to put 470n cap (C6 on your schematic), however, I tried to solve that. Since I didn't build it on a breadboard (I made PCB thinking it will work fine 8) ), I decided to model it in LTspice and experiment there, to avoid PCB damage :). So I did that and started tweaking various parts, finally settling at published schematic. I am currently very busy with regular job, so I can't unbox it and try different options (swell, for example), but I will do that in few days.
However, if you are still in breadboard phase, you can try to alter R10 and R11 and see what will suit your needs - it made ripple gone in my case.
And I forgot why I've changed C4 on my schematic to 1u (C3 on yours)! Sorry... :(
Thanks mate.
I must of made a gaff.
If you still have the sim can you see what the voltages on the last transistors are for me pls.
This is the file so you can try to mess with it yourself. I believe that the most important change is R11 on your schematic, it shall be 100 Ohm, not 100k.
http://www.cad.rs/d/AQR-noise-gate.zip
It was the cap hanging off the base of the last transistor that was causing the thump. I made mine 10uf.
Sorted.
If I use a 100 Ohm between the two last transistors it doesnt work as a sweller.
I found the minimum for my application between 22k~47k.
You have to be mindful of the collector voltage when changing the resistors..
Have you sorted out the ripple with those resistors or not?
Yes thanks just needed a bigger cap on the base.
I'll write it up when I finish work.
Quote from: Kipper4 on February 08, 2018, 07:04:39 AM
It was the cap hanging off the base of the last transistor that was causing the thump. I made mine 10uf.
Sorted.
If I use a 100 Ohm between the two last transistors it doesnt work as a sweller.
I found the minimum for my application between 22k~47k.
You have to be mindful of the collector voltage when changing the resistors..
Maybe you can use 100 ohm fixed in series with 100k pot for swell controll?
I'll come back at the weekend over a cup of coffee or two and write some more.
Since getting back form work I've got one of those annoying little lead cut offs in my toe and given my left pink a second degree burn with the hot melt gun.
Bonus is I've wired up an indicator led and the boards nearly ready to box.
I have one more possible ammendment in stall. I'll see what happens on the breadboard with that one.
I'm off to bed to cry myself to sleep :).
"Night John boy"
Heres where I am with the sweller/gate (actual build varies from the breadboard in that charge cap mostly.
It does what I wanted. Not just a gate but a gate as an effect and a sweller too.
(https://i.imgur.com/88VBuNM.png)
Is this C11 really necessary?
Real world pcb wouldn't function just with the 470nf.
Might be faulty?
So I tried 470n 1u 2u2 4u7 10u
That's what worked best.
I can't simulate the behaviour on the breadboard.
I tried a series R between cap and gnd.
Has to be a small value.
Not worth the part probably since it didn't really solve the issue.
Here's some fooling.
My noise gate is without 470n (C11) and I have 10u (not swelling, because my R12 is 100R). So I thought that you don't need C11 at all, since you also have C10 in your schematic at the moment.
I couldn't get the range of swell times I wished for without the // cap arrangement.
I could sacrifice the 470n and a 10 but it will limit the range of swell effects.
I'm not sure why it's behaving like this. The breadboard version does not display such behaviour. Although I've had my problems with it.
A 100 ohm will make it work better as a gate.
I've seen several schematics with a small ceramic cap in parallel with a large electro, though usually for power supply filtering.
IIRC, the idea is that the electro could have significant parasitic inductance or resistance (or maybe both? I forget) that cause it to filter poorly at high frequencies.
In other cases, the electro filters the entire supply rail, and *every* IC gets it's own ceramic decoupling cap as close as physically possible to the supply pins. This appears to be nearly-universal in most fields of electronics -- virtually every opamp datasheet suggests it. In that case, I think they're entirely to counteract stability issues stemming from the resistance of the PCB traces themselves.
My original values were the ones that worked better for me, regarding opening/closing times, as well as swell...
I really like this discussion, as we tend to learn a lot more when things do not match our needs. Congratulations, boys! :)
Boldly resurrecting this thread as a noob to ask the AQR experts, do you think a TL071 IC can be used in place of the 741?
Rising from the ashes, you can use any operational amplifier in this circuit, because the main idea of the project is to keep things simple with easy-to-find parts, or whatever-is-available parts... :) :) :)
Has anyone built this?
I'd love to know.
Rich
It will be nice to get the layout, too. ;)
Quote from: Kipper4 on December 14, 2022, 11:54:14 AM
Has anyone built this?
I'd love to know.
Rich
nice to see you back, Rich; didn;t you build this, back on page 1?
I did indeed and thanks for the welcome back.
Page was a long time ago.
How are you Duck?
Just wondered if any others built it is all....... :icon_lol:
Quote from: Kipper4 on December 15, 2022, 12:50:22 PM
Just wondered if any others built it is all....... :icon_lol:
Nope..!! :icon_wink:
(till some willing guy make a layout..)
P,S,
Glad to see you back, Rich.. :icon_smile:
If I get time I'll see if I have a layout.
Thanks Antonis
Is post #32 a final schematic?
I believe so Blackie. Hope your ok mate ?
I think R3 probably gets bias from VB rather than +9v.
Hello Rich.