[sdiy] Vactrol control ideas wanted

[Peter Grenader]

A Panner.  Seems to me, with the inherent slow-motion release of the
vactrol, it's a perfect candidate for panner applications in that it would
more than likely smooth out the dreaded 3 dB drop in the center.

Sounds reasonable.

Another great vactrol application - little men.  With two leads coming out
the top (arms) and two coming out the bottom (yes, you've got it - legs),
you've got the makings of a one heck of a swell man.  Hell, his torso would
be somewhat shaped like Bob Moog's anyway.

You just need a head, and this is where your tantilum cap comes it. Any
value should do.  Little shoes from switch caps, a tie zip-tie belt and
bingo - a little companion to sit with you while you solder.

huh?

- P







 René Schmitz wrote:

> Hi Harry,
> 
> 
>> I'm planning a vactrol based phaser module (yeah, I know...
>> how original :^)
> 
> In my tube based phaser I've used three expo convertors of the ARP-Style
> (PNP/NPN). Its a six stage design, and this allows me to offset two of
> the vactrols with respect to the third one. By that I get a "notch
> spreading" control (one expo receives the Spread-CV directly, the other
> inverted. I found this to be easier than to experiment with different
> caps, and the big plus is you can change the character with a front
> panel control. (I didn't bother to bring out a CV, but that would be
> straight forward.)
> 
>> 2) Control the Vactrols by running them all in series, with one
>> Photocell fed
>> back into the control circuit.  This is an adaptation of the National
>> Semiconductor
>> "Analog Multiplier" found in AN-20.  However, this version will not have
>> one LED
>> illuminating multiple photocells.
>> 
>> pro: (subject to matching) the photocell resistance can be accurately
>> specified
>> con: its more complex
> 
> con: you also loose the dynamic property of the vactrol.
> 
> Cheers,
> René