Cheap and Easy DIY vactrol

[mcknib]

Here's a link if anyone wants it for making a cheap and easy DIY Vactrol using a 5mm plastic LED bezel not ground breaking or original by any means just a wee bit of a different approach for the hard to find tutorials on making one that looks fairly good and performs fairly well:

http://www.guitarpcb.com/PDF%20Files/DIY%20Vactrol.pdf

It's downloadable in PDF format

Thought I'd contribute something as a way of thanks for all the help, advice and knowledge I've received here

*EDIT* changed the link to a complete and updated PDF that advises that the rubber you use for the end caps should of course be non-conductive so if you purchase any make sure it's non-conductive some rubber sheets do contain carbon black powder. I read digi2t's post and thought whoa I never mentioned that! so cheers for that important note

[Will.mendil]

I tried to make these before but did not know how to test them. Does someone have a simple test circuit to check the behaviour of these diy vactrol?

[mcknib]

I don't over test them you could use the datasheet for the one you are making and test it under those conditions i.e so many mA gives you whatever resistance, speed / response time etc.

There is a link here where Flo FX used a more scientific method than mine to run his tests

https://sites.google.com/site/flofxdiy/optocouplers-measurements


All I do is once it's made test it under normal room light by taking the resistance on the LDR end then completely cover it and test dark resistance which usually is in the M ohm off range and lastly I clamp the LED legs around a 3v coin cell battery in my vice which should fully illuminate the LED and check it for bright on resistance not scientific but let's you know it works when you can't see any light from the LED and I've never had a problem when it's in the circuit I'm using it in.

There are some circuits that would obviously need much more precise vactrols if that's the case I'll spend the money on a commercial one.

You could if you really wanted to make a circuit on a breadboard with a few resistors or pots to give you your desired test current to the LED I'm over simplifying it but it shouldn't be too difficult. Google vactrol testing circuit I'm sure there will be something around.

[Kipper4]

I'm sure Duck Arse made a vactrol testing rig. I built it.
Thanks for sharing Billy

[digi2t]

http://www.diystompboxes.com/smfforum/index.php?topic=95269.msg824665#msg824665

[Will.mendil]

@mcknib    Thanks I'll check this up.I'll get back to you if I ever get any cool stuff to post

@Kipper4    duck arse ? have I missed something?

[mcknib]

Nice Digi2t never saw that in the search lots of great testing info

and Will.mendil  duck-arse is one of the more knowledgeable and very helpful guys on here:

http://www.diystompboxes.com/smfforum/index.php?action=profile;u=35188

perhaps he'll chip in and save you searching his 4436 posts for the test rig

[duck_arse]

I still had to go and search.

http://www.diystompboxes.com/smfforum/index.php?topic=107530.0

another thing for if you do different types of vactrols, is to sleeve the led leg for polarity with sleeving the same colour as the led. not waterclear, obviously.

you can do similar with the ldr, if you have different types from the GL55xx series. black for a 5516, orange for a 5539, etc, you get the idea.

[you used to call me "duck's bottom", will.m.]

[mcknib]

I still had to go and search.

I knew you were a good egg Mr Duck cheers and nice circuit too

For you: