Electronics > Projects, Designs, and Technical Stuff

Where to buy a good vactrol ?

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floobydust:
I recall CdS photocells are most sensitive to green, like the human eye. CdSe are red-sensitive. But there is doping involved I think for higher gain but getting slower response.
I'm not sure why Vactrol is using red LED's - perhaps they were brighter/cheaper back in the day? Some even used neon lamps. 40mA LED drive for a 5mm part seems oddly high, so they need brightness.
I would try a CdS photocell with a high efficacy pure green LED in some heatshrink tubing and do some pulse experiments. The response time made the sound of a compressor what it is, so important to try keep that if cloning vintage gear. It seems faster CdS parts have shallower slope.

The parts are still relevant. Stumbled onto Jim Williams (July 1990), "Bridge Circuits Marrying Gain and Balance", Linear Technology Application Note 43
He uses Vactec VTL5C10 or Clarex CLM410 in an ultralow (better than a JFET) distortion sine oscillator 0.0003% or 3ppm fig.48 wow. Bless his soul.

schmitt trigger:
Your comment made me research further.

I found the following datasheet. It is indeed a CdSe photocell and the sensitivity peaks at 690 nm. Definitively blood red.
See attached.

Jan Audio:
Why are those amerikan shops so racist ?

2N3055:

--- Quote from: Jan Audio on April 04, 2020, 01:14:24 pm ---Why are those amerikan shops so racist ?

--- End quote ---
:-// :wtf:

schmitt trigger:

--- Quote from: Jan Audio on April 04, 2020, 01:14:24 pm ---Why are those amerikan shops so racist ?

--- End quote ---

 ??? ?

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