[sdiy] Three Leg Photocell Hunt

[mark verbos]

Let me try this again...


Kyle,

If by "potentiometric response" you mean that one side of the center- 
tap gets greater resistance while the other gets less, you are  
mistaken. This is not how dual vactrols work. Both sides of the center  
tap have the same resistance throughout the range. I don't think you  
will have any luck finding a 3 legged photocell that works as a drop  
in replacement for a pot, unless the pot is being used as a variable  
resistor.

Mark




On Mar 30, 2010, at 3:09 PM, Kyle Stephens wrote:

> Ahoy...
>
> I'm looking for a three terminal photocell with potentiometeric  
> response (the exact log/linearity isn't important) - like what's in  
> a three legged Vactrol.
>
> I suppose I could try and pop one of those open to get what I have  
> in mind, but it'd be a waste of a good Vactrol, assuming it's even  
> possible to saw through and chip away all the potting.
>
> A max resistance of ~10M would be grand, as would a turn on time  
> less than ~50ms.
>
> Any leads anywhere? This is the best I got so far, the "MI (TH  
> Series)":
>
> http://www.macron.com.hk/productlist.htm
>
> The exact terminology seems to part of my problem finding one - what  
> to call it, a (dual?) optocell, photocell, photoresistor,  
> optoresistor, CdS cell, "Cadmium sulfide" spelled out in full, etc.?
>
>
> _Kyle
>
>
>
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