[sdiy] Vactrol Selection (for 2 meg pot)?

[phillip m gallo]

Cynthia,

Do i understand that you want to dynamically change the "flash" rate of your
strobe such that across a small period of time (i.e. across a 2 second
period, flash rate ramps from .1Hz to 10Hz)?  If so would an Envelope
Generator make more sense to drive the LED?

regards,
p


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Cynthia Webster
Sent: Thursday, May 09, 2002 5:08 PM
To: Diy
Subject: [sdiy] Vactrol Selection (for 2 meg pot)?


Hi Everybody!

This vactrol discussion going on lately is very interesting isn't it?

It got me thinking... I have a cheapo ten-dollar strobe light, and I'm
trying to add a way to voltage control the flash rate.

There was a 1 meg pot controlling the flash speed, and I found that the more
resistance in place of the pot - equals the slower the flash rate...
Aactually, I like a 2 meg pot more that the 1 meg original -
because it's slower, (but three meg didn't make much of a difference).

I'm using a Modcan modular system and know that the square wave outs from
the oscillators are zero-to-five volts That I'd use to control the LED part
a vactrol...

so How would I pick a vactrol that takes a 0-to-+5 Volt control to
manipulate a 0-to-1-Meg ohm range circuit?

Are there any parameter charts of currently available Vactrols?

The challenge here is to do it all passively, as all the circuitry in the
Strobe is 110 (at least I think so) because there is no power supply and
there aren't any kind of voltage regulators or anything like that inside the
tiny case.

I'd originally thought of making an opto-isolator for this with a "white
light" led and a cheapo Radio shack photo-resistor heat shrinked in a tube
together.  Would the vactrol be better?

Fun with Vactrols?  Any ideas guys?

Thanks

Cynthia

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