[sdiy] Interest in characterized vactrols?

Bob Weigel sounddoctorin at imt.net
Sat Jul 13 13:08:24 CEST 2013

On 7/13/2013 1:56 AM, Jason Nanna wrote:
> A while back I designed a device to characterize vactrols for on
> resistance, decay time to 100k, and dark resistance at 10 seconds, for
> a range of drive currents. I could also modify this to provide
> resistances at various PWM values at a specified drive current.
> I got a bunch of surplus vactrols that I believe were discarded
> because they're outside of part specs, for a video synthesis project.
> I'm looking for specific characteristics, and when I'm done
> distributing these kits, I'm sure there will be a ton left over which
> fall outside of my own spec. I'm curious if there's interest in the
> community for a website where you could put in search parameters and
> have a 'closest match' returned which could be purchased...
> It would be a bit of work to go through the effort of putting this
> together, which is why I'm trying to gauge interest in advance. Please
> let me know if this would be of use to you, as well as specifically
> what you're looking for them for. Do you need matched sets? What is
> the most relevant characteristic for you?
> I believe these are silonex vactrols - they are mostly stamped NSL
> 7053 and some of them bear markings like 'SR3', as in 'NSL-32SR3'
> I've also got a quantity of VCL53/2's that could be specified.
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Nice.  I got some surplus russian ones a while back.  But tonight I was 
just doing a study on the Hamamatsu 0805 since people are wanting to 
order the last few I have.  Over the last 6 I have I found a range of 
nearly a factor of 2 in values but the worst match was just off maybe 4 
percent I think it was between the two halves. I tried to clone it ...a 
yellow led measured nearly the same on diode check but the curve is 
different with the ldrs I used on that first model.  Mine is nicely 
matched though til it goes into high resistances. I'll have to try it in 
a clone of the mutron circuit some time.

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