# Constrictor Gain Reduction LED



## DSpenceATL (Jun 11, 2022)

Hello all!

I have been a long time lurker on the forum, but today is my first time posting. 99% of issues I've had during builds I've been able to troubleshoot just by reading threads here, so thanks so much for that!

I have just finished a Constrictor build, and it's working great! I would love to add a second LED to show gain reduction. I've done a lot of searching for answers to this, and have yet to find anything satisfactory. I found an old thread on another forum from 2010 which never got a full answer, and I've tried spent some time with IvIark's vero layout over on tagboardeffects, but to no avail.

From what I understand, I need to attach a 330R resistor on the positive side of this second LED, and tap into the LED side of the Vactrol. Can anyone tell me the exact points i should be hooking up the + and - to, in reference to the Constrictor board?

Thanks so much!


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## MichaelW (Jun 11, 2022)

DSpenceATL said:


> Hello all!
> 
> I have been a long time lurker on the forum, but today is my first time posting. 99% of issues I've had during builds I've been able to troubleshoot just by reading threads here, so thanks so much for that!
> 
> ...


I'm trying to picture how that would work. I've actually got my Constrictor fired up right now trying to record a track. The second led would come on when it peaks? Or hits the peak limit? I would up using numbered top hat knobs on my build so I can remember my settings for different pedals.


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## DSpenceATL (Jun 11, 2022)

In my mind, the second LED would come on any time compression is being applied. I don't know if it would only exist in one of two states, off or on, but I would think that if it responded similarly to the opto that it would have varying degrees of brightness depending on how much compression is being applied.


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## DSpenceATL (Jun 17, 2022)

Giving this a bump


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## Chuck D. Bones (Jul 1, 2022)

Try installing an LED and limiting resistor from IC2-7 to IC2-1.  LED cathode toward IC2-1, same as the VTL5C10.  Keep the limiting resistor larger than 1K so as to not steal too much current from IC2.


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## DSpenceATL (Jul 1, 2022)

Chuck D. Bones said:


> Try installing an LED and limiting resistor from IC2-7 to IC2-1.  LED cathode toward IC2-1, same as the VTL5C10.  Keep the limiting resistor larger than 1K so as to not steal too much current from IC2.


Brilliant! I can confirm this works. I seem to have had better luck using a less bright LED, but it still seems a tad on the dull side. I used a 3.3k resistor for current limiting, will moving that closer to 1k yield a brighter light do you think?


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## Chuck D. Bones (Jul 1, 2022)

Use a clear super-bright and you won't need such a small resistor.


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## DSpenceATL (Jul 2, 2022)

Chuck D. Bones said:


> Use a clear super-bright and you won't need such a small resistor.


Absolutely perfect. Thank you SO much for helping me declutter my bench! Will copy and paste your response in the troubleshooting thread in case anyone stumbles across that one too.


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