# NSL-32 Vactrol installation



## joelorigo (Sep 9, 2020)

I am building the Aion Gale and it has a part that in my 1.5 years building pedals I have never used before. A NSL-32 Vactrol. I just wanted to make sure I am installing it correctly. There is a white dot on the part that I'm assuming matches up with the "+" on the pcb. Based on photos of other finished Gales it seems right but I thought I would post here first - assuming I was right has been wrong in the past ?


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## Mcknib (Sep 10, 2020)

The dot is the negative cathode side here's the datasheet



			http://datasheet.octopart.com/NSL-32SR3-Silonex-datasheet-93144.pdf
		


Just for info you'll find that most components have datasheets if you ever need information, not that they're always easy to decipher! 

They contain varying degrees of information from electrical characteristics to physical size, maximum voltage ratings  etc


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## BCS-127 (Sep 10, 2020)

Hi there - I'm new to the forum, but remember having the same question with my Gale build a while back. If I remember correctly, the white dot indicates the negative terminal for the LED of the NSL-32.

The schematic shows the vactrol LED is driven by a bridge rectifier, so I don't think the polarity will matter for limiter circuit.  It should work the way it is shown in the picture ( I'm sure others will chime in if I'm mistaken ☺)

The Gale is a killer boost - I really dig mine!


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## BCS-127 (Sep 10, 2020)

I looked at the schematic again and my previous response was wrong.  The NSL-32 polarity does matter and the limiter will not work if the anode and cathode are reversed.

Sorry for my error!


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## joelorigo (Sep 10, 2020)

So it seems then the white dot needs to be on the other side (the right side), but still at the top of the PCB, like this:


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## BCS-127 (Sep 10, 2020)

That looks good - White dot upper right.


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## granny (Jul 27, 2022)

Mcknib said:


> The dot is the negative cathode side here's the datasheet
> 
> 
> 
> ...


Actually, the dot is marking the anode, the positive pin for some reason. I was misled by such discussions and my diy compressor pedal buzzed when strumed hard. I reversed the octocoupler pins and everything worked as it should.


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## fig (Jul 27, 2022)

granny said:


> Actually, the dot is marking the anode, the positive pin for some reason. I was misled by such discussions and my diy compressor pedal buzzed when strumed hard. I reversed the octocoupler pins and everything worked as it should.


Ouch. Different makers mark them differently. You can perform a diode test on them before installing.


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## granny (Jul 27, 2022)

Yes, the diode test should clear things for sure. Though I have seen this part being sold by some webshops and they state in the product picture the marking of the positive pin. But you're wright different makers different markings.


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## Diynot (Jul 27, 2022)




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## Mcknib (Jul 27, 2022)

granny said:


> Actually, the dot is marking the anode, the positive pin for some reason. I was misled by such discussions and my diy compressor pedal buzzed when strumed hard. I reversed the octocoupler pins and everything worked as it should.


I just went by the silonex datasheet image defo looks like the dots cathode to me, I could be looking at it  wrong though


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## Diynot (Jul 27, 2022)

I just ran the NSL I have through my little component tester and the dot on mine supports @Mcknib, the dot is on the cathode (-).


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