switching vactrols

syn · Apr 18, 2010

Hi

I'll be building DAOC and was thinking of switchable vactrols, (also I'll go for a full wave rect. as in Kubi advanced version rather than having leds in parallel & anti parallel). Idea is to have VTL5C4/2 and VTL5C3/2 which is much faster, switchable from the front panel. I'm not sure is it ok to keep resistor side in parallel of all vactrols (4vactrols in total in parallel) at all times hard wired, and to switch only the led part(s), or shall i switch between vactrol "sets" (2xVTL5C4/2 or 2xVTL5C3/2), both, the resistor and the led part. Hope this sounds clear.
Thank you

PRR · Apr 19, 2010

If the light is dark, the LdR will quickly go to 1Meg and soon over 10Meg.

In many cases, this is equivalent to yanking it out.

If that's acceptable, then just switch the LED.

syn · Apr 20, 2010

Thank you PRR. Switching the led part only will work, I tried it. However there is less compression with VTL5C3/2 for the given threshold setting. No big deal.

tv · Apr 20, 2010

But did you think on wiring the both VACTROL SETS in SERIES and HARD SHORTING one series at the time with a ON-ON switch?

This should get closest to the "clean" modus-operandi. Ymmv...

syn · Apr 22, 2010

Thank you tv, great idea.
Cheers

tv · Apr 23, 2010

You could do that on BOTH "sides" of a vactrol: on "photo-resitor" side and on the "led" side (my post wasnt really clear about that).

In essence, you "stack" them, but then you short-out ("remove" from circuit) those who arent needed in a particular "mode of operation".

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Should I patent that? But of course, hey!