DIY Vactrol

[Matthew Sanford]

Just wanted to share the method I'm going with. Shrink was...not quite right.
So inexpensive Xingyheng ldrs, flat topped green leds. I cut a piece of electrical tape about as wide or so as the two together, drop of glue on led, stick em together set on the e-tape and get it lined up together nicely with legs the same, roll the tape round and push excess down on the led. Then two pieces of black silicone tape, I used 1" wide tape cut 3/8-1/2", hold an edge on the back, stretch the other side and roll it on. The other piece is stretch wrapped around the other way between the legs to keep them separated and seal the bottoms.

Works well. I'd done it without the electrical tape but silicone gets thin when stretched so not quite as light tight. For the GL5537 (16-15k -> 2M per seller info), but using StompLFO Offset min and max got it 445R - 4.7M. Full dark was 20M+, I did get one showing just over 200R on the bright side. Not bad!

[PRR]

Little shirt-cardboard boxes, painted flat-black inside and out. Could be a bit leaky when out in the open on a bright workbench. Dead-dark when also inside a metal case, even at Lunchtime Concerts In The (bright sunny) Park.

Is shirt-cardboard a thing anymore?? I don't mean a T-shirt display, I mean the stuff the laundry returned Dad's starched white shirts on.

The backing on cheap note-pads?

[Matthew Sanford]

Interesting. I think the same flat cardboard does come in new shirts still, sometimes, but i only dry clean my trench.

I was thinking about the proximity of the led light to the ldr, if some distance's lux reduction would have an effect on the speed of resistance change with same light changes, and other ldr properties. I had read a guys thing on micbuilders about using highly reflective film as a light mic, light bouncing off it to an ldr (mostly about best way to do that, if I recall) and registering the vibrations from the voice...had thought maybe similar with a piezo for a pedal, though not sure the point of it's an accurate replication.

This way works great though, didn't take long to make 12, and thinking to just roll the tape on before the glue dries, and just have to stretch the silicone well so it sticks to itself.

[GibsonGM]

The venerable Forrest Mimms gave a design for a 'lightwave transmitter/receiver' in the Radio Shack book "Communications Projects", probably available free online. Looks infinitely hackable for DIY purposes!   

Willing to bet the reconstituted signal isn't too high fidelity. The re-do of Battlestar Galactica 15 or so yrs back had odd-sounding comm's while in their fighters. I explained why to a friend...for security, they were using lightwave transmission   The Cylons couldn't intercept that...

[Matthew Sanford]

My brother has been on about getting me to watch the new one, I'll get there.

They just put fiber in my city, lightwave transmission is the way to go! Was thinking parabolic lenses to focus light into fiber to feed solar...But less seriously, there seem to be many out of the box (inside a properly designed reflective box) ways to use it's speed to create funky effects outside of vactrols slower change way. Hmmm...

[amptramp]

It sounds like you may have a way to implement isolated popless, clickless switching that everyone would like for their pedals.  True bypass has its uses but the major manufacturers have avoided it for a reason, mainly expensive and unreliable 3PDT switches.  You can switch from a series resistance of several hundred ohms to something in the megohm range and after a suitable delay, switch the output of the vactrol in its high impedance state to ground with a saturated transistor and get better on:off ratios than most switching systems.

[Matthew Sanford]

It sounds like you may have a way to implement isolated popless, clickless switching that everyone would like for their pedals.  True bypass has its uses but the major manufacturers have avoided it for a reason, mainly expensive and unreliable 3PDT switches.  You can switch from a series resistance of several hundred ohms to something in the megohm range and after a suitable delay, switch the output of the vactrol in its high impedance state to ground with a saturated transistor and get better on:off ratios than most switching systems.

So if I understand, clicking the switch to saturate the transistor and vactrol to gently release it to ground?

Edit: I think I get it, vactrol in series, it's slow change is the delay, and the transistor is always saturated.

[printer2]

My brother has been on about getting me to watch the new one, I'll get there.

They just put fiber in my city, lightwave transmission is the way to go! Was thinking parabolic lenses to focus light into fiber to feed solar...But less seriously, there seem to be many out of the box (inside a properly designed reflective box) ways to use it's speed to create funky effects outside of vactrols slower change way. Hmmm...

Had me waiting each week for the next episode. was an amazing series.

I scavenged some LDR off of Yamaha organs, used for the foot pedal volume control (sure there is a better name). Some good speakers from the organs if anyone wants to pick some up cheap, usually free (avoid the 'ear' speaker of course).

[Ben N]

Little shirt-cardboard boxes, painted flat-black inside and out. Could be a bit leaky when out in the open on a bright workbench. Dead-dark when also inside a metal case, even at Lunchtime Concerts In The (bright sunny) Park.

Is shirt-cardboard a thing anymore?? I don't mean a T-shirt display, I mean the stuff the laundry returned Dad's starched white shirts on.

The backing on cheap note-pads?

Pizza slice cardboards should do it.

[Matthew Sanford]

Dang it, all these people saying my older brother is right! Gotta squeeze it in...though I think he wants the Expanse in my eyes and ears first...

All this cardboard talk has me thinking on thick cardboard tubes/straws, or the black plastic one at the center of the pups potty bag rolls...I knew they had a use! I guess after current project I'll have to measure differences caused by slight distance increases, wonder if it gleams the cube like magnetism or proximity capacitance? I guess light intensity vs distance will end up a google search for me...

Gotta think on that popless, 3pdt-less bypassing. I usually think of vactrols in a potentiometer way, but maybe flip flop led control or a logic chip to feed in what the we want to output. My brain was thinking on panning option box to plug effect chains through to vary which goes out, why not switching done the same to pan over to the chosen one?

[duck_arse]

I scavenged some LDR off of Yamaha organs, used for the foot pedal volume control (sure there is a better name). Some good speakers from the organs if anyone wants to pick some up cheap, usually free (avoid the 'ear' speaker of course).

I think the foot pedal volume control is a swell name.

[marcelomd]

Just wanted to share the method I'm going with. Shrink was...not quite right.
So inexpensive Xingyheng ldrs, flat topped green leds. I cut a piece of electrical tape about as wide or so as the two together, drop of glue on led, stick em together set on the e-tape and get it lined up together nicely with legs the same, roll the tape round and push excess down on the led. Then two pieces of black silicone tape, I used 1" wide tape cut 3/8-1/2", hold an edge on the back, stretch the other side and roll it on. The other piece is stretch wrapped around the other way between the legs to keep them separated and seal the bottoms.

Works well. I'd done it without the electrical tape but silicone gets thin when stretched so not quite as light tight. For the GL5537 (16-15k -> 2M per seller info), but using StompLFO Offset min and max got it 445R - 4.7M. Full dark was 20M+, I did get one showing just over 200R on the bright side. Not bad!

Sounds interesting. Do you have any pictures?

[Matthew Sanford]

Why yes, thank you for asking! I took this picture of 6 of the sticky little buggers (stretched silicone does want to "melt" to itself) but neglected to add it to the post



And now my mind is on using them to make planner/faders to different busses to mix in different signal chains via LFO or other controls...being inspired by the ESP mixer, I think.

Well actually now thinking on different ways to use them instead of a 3pdt! Thanks amptramp for that brain worm!

[amptramp]

They look almost identical to the devices used in Fender amps from a while ago to isolate the tremolo oscillator from the signal.  All you need is the white dot that goes on the tube side of the terminal eyelet board and you could have something.  Of course, they used neon lights rather than LED's as drivers but the idea of a tremolo isolator is still a good one even in solid state circuitry.

[ElectricDruid]

Oooh GLOOPY!! 

Those look fine, and the numbers you were getting out of them look great. I'm sure you can come up with all sorts of inventive stuff to do with them.

PS: I like the idea of painting a single white dot on the side of them to make everyone think that they're "selected"

[Matthew Sanford]

Or maybe an evil eye on the side to reflect the designer's disdain back at them!

Early in messing with PT2399 when loving the after madness which would grow to obscene levels I had a thought of using it (envelope of it) to drive a vactrol divider, or bjt, to drain some of it off to keep it at a manageable feedback of delay. I think the slowness of a vactrol would let the insanity sit on the surface just a bit...

On the weird Stomplfo thing...ah, I'll send you a message to pick your brain...maybe learn my Thenevin too...

[Phend]

Lots of dead mice around. Has any one tried the red led from a dead optical mouse ?

[Matthew Sanford]

PS: I like the idea of painting a single white dot on the side of them to make everyone think that they're "selected"

Been a bit on this, had to make a new batch - no glue blue tape instead, silicone tapes sticky so stretched heat shrink shrunk, and they're selected!

[Ben N]

The venerable Forrest Mimms gave a design for a 'lightwave transmitter/receiver' in the Radio Shack book "Communications Projects", probably available free online. Looks infinitely hackable for DIY purposes!

https://www.zpag.net/Electroniques/Kit/Radio_Shack_-_Engineer's_Mini-Notebook_-_Communications_Project.pdf

[GibsonGM]

Yessir, that's the one. I still have the paper copies of some of those...the one for the 555 time still gets used, ha ha!  Good stuff!  Used to be able to grab them at the local Rat Shack for $1.99