[sdiy] Five-terminal Vactrol question

[Magnus Danielson]

From: "Alex C. Reed IV" <alex.reed at gatech.edu>
Subject: [sdiy] Five-terminal Vactrol question
Date: Wed, 3 May 2006 02:48:31 -0400
Message-ID: <E72CA4E4-FC81-4B7E-BD2C-7AF128E9108F at gatech.edu>

> I'm looking at a VTL5C3/2 5-terminal vactrol (http:// 
> users.ece.gatech.edu/~lanterma/sdiy/datasheets/vactrol/vtl5cx2.pdf)  
> but I am confused.  I know the two pins that correspond to the  
> cathode and anode of the diode, but the other three confuse me.  Is  
> there a fixed resistance between the outside pins (10MOhm, 3 and 5,  
> respectively) and the middle pin sweeps between the other terminals  
> (light-dependent potentiometer) or does the middle pin just give half  
> the resistance across the outside pins?

Isn't this two LDRs with pin 4 as common?
The hint is loud and big in the title "Dual Element Axial Vactorls".
Vactorls - yes, Axial - packaging style (semi-round with pins sticking out on
the axial ends). "Dual Element" hmm... :-)

> Thanks for any help, and sorry if the question is dumb.  I've always  
> made my own LDR cells (flat diode, light dependent resistor, and lots  
> of electrical tape).

Hehe... see Bergfotron for another way of doing basically the same, nick-named
"Bergfotroler" locally.

Cheers,
Magnus