Time for some Homebrew Vactrols !!

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Would you be interested in making your own Vactrols from Generic parts ?

Yes , i want to make some Vactrols !
122
97%
No , i'd rather pay for them from an established producer.
4
3%
 
Total votes: 126

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cleaninglady
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Time for some Homebrew Vactrols !!

Post by cleaninglady » Thu May 03, 2012 6:27 pm

First of all , i want to pay for respect to samuraipizzacat29 and valis for all their time and effort on the whole subject of Vactrols in the past week or so.

It is these kind of selfless , often time consuming gestures from fellow Wigglers that makes this place such a joy to be involved with and makes me want to give something back. :hail: :hail: :hail:

With all of the rising prices and supply problems , i think it is high time for some Homebrew Vactrols !

I'd be really interested to know if anyone has any experience in making them.

It would be great to have some Homebrew Vactrol experiment results available similar to those found on the datasheets for Excelitas Vactrols.

If we could get some LED / LDR combination close to that of the VTL5C3 , it would save alot of people alot of time , money and pains in the arse.

Is someone here in contact with any of the elder pioneers of synth module production ?
Perhaps some of those guys and gals could shed some light on this magical component that seems to be shrouded in mystery and black shrinkwrap ?

Has anyone ever cut a VTL5C3 open ? It would be great to see what the combination of components was inside and exactly how the light sheilding was most effectively achieved.

All i can do at present is ask questions but hopefully , if the combined knowledge of the Forum is posted here ; we may end up with something.

This is obviously not the first thread on this subject.

Great links have been posted by dmitri , decaying.sine , bleeps , Luka , fluxmonkey and many others here :

I'll put links posted in this thread and whatever i can find from other threads right here :

Building Vactrols

Measurements and build pics.

Grant Richter's Hairball using Modelling Clay

Great Japanese page with indepth test results on many parameters.

A picture of exposed Vactrols on a Buchla 261e board.

Look close at the Red LED's laying on their side facing some LDR's , that's them.
Last edited by cleaninglady on Fri May 04, 2012 7:41 pm, edited 4 times in total.

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valis
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Re: Time for some Homebrew Vactrols !!

Post by valis » Thu May 03, 2012 6:37 pm

cleaninglady wrote:First of all , i want to pay for respect to samuraipizzacat29 and valis for all their time and effort on the whole subject of Vactrols in the past week or so.

It is these kind of selfless , often time consuming gestures from fellow Wigglers that makes this place such a joy to be involved with and makes me want to give something back. :hail: :hail: :hail:
Thank you for saying that. If I can give back a little to this community that has given so much to me than I'm happy.

Anyway, here's Scott Stites tutorial on optoisolator rolling

http://web.archive.org/web/200904142352 ... a52a376625

And don't forget about this thread

viewtopic.php?p=756093&sid=e3d6a61e48b4 ... 1fc8b964eb

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Orbless
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Re: Time for some Homebrew Vactrols !!

Post by Orbless » Thu May 03, 2012 6:43 pm

valis wrote:
Anyway, here's Scott Stites tutorial on optoisolator rolling

http://web.archive.org/web/200904142352 ... a52a376625
holy shit that site is impossible to read anything on!

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valis
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Post by valis » Thu May 03, 2012 6:45 pm

lol. You kind of have to highlight it. There's some good info if you do.

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cleaninglady
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Post by cleaninglady » Thu May 03, 2012 6:47 pm

Cheers valis !

Maybe i should contact Scott Stites and see what he has to say.

Keep 'em comin' people , this could be a really great thread...

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Orbless
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Post by Orbless » Thu May 03, 2012 6:47 pm

even highlighted I was struggling. Maybe the combo of the background color, almost matching text color and small size. It was gibing me a headache.
I think I will copy and paste the text into something else so my eyes don't explode

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cleaninglady
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Post by cleaninglady » Thu May 03, 2012 7:01 pm

Orbless wrote:even highlighted I was struggling. Maybe the combo of the background color, almost matching text color and small size. It was gibing me a headache.
I think I will copy and paste the text into something else so my eyes don't explode
If you click on the first and larger header that says 'Rolling Your Own Optoisolator' it takes you to a page with easier to read text.
I agree that first page is brain-splittingly difficult to make out. :zombie:

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andrewF
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Post by andrewF » Thu May 03, 2012 7:22 pm

one good page on diy vactrol is by Motohiko Takeda
http://www.aleph.co.jp/~takeda/radio/phaser/indexE.html

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cleaninglady
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Post by cleaninglady » Thu May 03, 2012 7:24 pm

Cheers Andrew , copied and pasted up top. :sb:

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ersatzplanet
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Post by ersatzplanet » Thu May 03, 2012 7:50 pm

I am interested more in the 5-legged variety of Vactrol that act just like a pot (all three legs). The data sheet for the VTL5C4/2 mentioned in the eye-exploding website article is one of these type. The Build your own version shown uses two LDRs sharing one leg and being lit from one LED. I can't see hoe this would work unless one LDR has resistance high with light and the other has resistance low with light. Am I missing some face-palm moment here? with the same type LDR wouldn't light just affect both LDRs the same way lowering the resistance to both "outer" legs?
-James

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Post by DGTom » Thu May 03, 2012 8:19 pm

I don't think the dual vactrols act like pots tho do they? If they did then you wouldn't be able to use either / or in designs like the Buchla LPG.

For example, if you compare the Easel LPG to the 292 they are quite similar but the former uses 2 single vactrols & the latter uses a dual & I'm pretty sure the Fonik / TW variants spec either.

I've built one of Foniks boards using 2 LDRs & an LED. . . no cover, leaks like a machine gunned colander but it works & if you put it in a case with lots of blinken (sequencer) modules you don't even need to plug a CV into it :omg:

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Post by toppobrillo » Thu May 03, 2012 8:22 pm

Am I missing some face-palm moment here?
yes, it's just 2 LDRs connected in series, with the "center tap" available as the middle lead

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ersatzplanet
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Post by ersatzplanet » Thu May 03, 2012 8:56 pm

toppobrillo wrote:
Am I missing some face-palm moment here?
yes, it's just 2 LDRs connected in series, with the "center tap" available as the middle lead
Well this diagram from the data sheet is very misleading. It shows a circuit exactly like a pot with a wiper and two outside taps - not to resistors in series with a center tap. I have one of these in a box somewhere and I will have to test it out.
Image
-James

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toppobrillo
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Post by toppobrillo » Thu May 03, 2012 9:11 pm

yeah, that is indeed a misleading diagram.

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bleeps
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Post by bleeps » Thu May 03, 2012 10:26 pm

With any luck they'll have a dual...

Image

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Post by toppobrillo » Thu May 03, 2012 10:30 pm

^like!

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clarke68
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Post by clarke68 » Fri May 04, 2012 12:46 am

Arrite...here's my first homebrew vactrol:

Image

I had to fill a Tayda order up to the $5 minimum, so I got some of their LDRs and ultra-bright LEDs and wrapped 'em in a little shrink-wrap tubing.

What do I do now?
DIY Euro synth panels: Synthcube

clarkerobinson.com - music, video, synth panels, and more!

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Isaiah
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Post by Isaiah » Fri May 04, 2012 12:53 am

Last week I ordered LEDs, two types of LDRs and some black epoxy from Farnell.
I will report back when I've experimented...

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snufkin
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Post by snufkin » Fri May 04, 2012 5:52 am

if we can come up with a sandard led ldr combo with quick reaction/decay time that could effectivly solve our problem you may have to build a few at a time

really it's the speed thats the issue here
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Post by Jarno » Fri May 04, 2012 7:23 am

I don't think light leakage is that big an issue, bit of heatshrink and you're done, specially for something that's residing somewhere in an enclosure. IIRC, in my Joe Meek MQ3, the LDR just sits on the board, with a led looking at it, no shielding whatsoever.
The big thing is response, all those LDR's you can buy have such a wide variation on several parameters, that you'd have to buy an aweful lot of them and do binning yourself. IMHO, that's what you pay for if you buy a readymade one, you don't pay for the LED, the LDR or the nice light shielding but the fact the supplier makes 10million LDR's, and takes the time to do elaborate binning (resistance on and off, speed on and off) of each LDR. Possibly, all the loose piece LDR's you can buy for little money are simply ones that don't fit in a solid category, and are hopeless to match yourself (although that's just guesswork). You never seem to find any specs for them, the nice ones you can get at Rapid are an exception, but at 1GBP each, not exactly cheap.

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Post by Paradigm X » Fri May 04, 2012 9:10 am

Orbless wrote:even highlighted I was struggling. Maybe the combo of the background color, almost matching text color and small size. It was gibing me a headache.
I think I will copy and paste the text into something else so my eyes don't explode
Out of interest if youre using firefox, go to view, then page style and choose no page style and itll be standard formatting. :bacon:

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cleaninglady
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Post by cleaninglady » Fri May 04, 2012 9:11 am

It will be great to hear any results from either Clarke68 or Isaiah ; scientific or otherwise , it's all progress towards some sort of idea of what fits our purposes.

I will get some LDR's in my next run of ordering but it might be a few weeks before i can do any putting together of Homebrew Vactrols.

I was thinking that i might try to contact Motohiko Takeda (...thanks andrewF ) and see if he can shed any light on LDR values to achieve VTL5C3 specs.

I think collectively as a starting point , this is what we are after ; am i right ?

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Paradigm X
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Post by Paradigm X » Fri May 04, 2012 9:18 am

Im liking this thread tho. Even moar DIY than DIY!

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cleaninglady
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Post by cleaninglady » Fri May 04, 2012 9:20 am

:cloud: Just trying to give a little back to these excellent dudes.

mckenic

Post by mckenic » Fri May 04, 2012 9:51 am

This stuff might be useful...

http://www.plastidip.com/home_solutions/Plasti_Dip

Got some when I was reading the Collins DIY book - to my shame, Ive not opened it yet!

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