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[Anirban]

Hi,
 
I have just disassembled a CdS light meter from the seventies (in order to calibrate it), and I notice the photo resistor cell has three pins. I figured out after tracing the circuit  diagram that one is a common pin, and the other two  are connected to two pots. The other terminals of the pots are then connected together
 
I have measured the resistances between the two non-common pins of the cell and the common pin (they are 15 kOhm and 35kOhm), Probably the CdS cell is a composite of two individual cells, but I cannot figure out whether these cells are connected in series or parallel.
 
Have anybody else seen such a photo resistor?
Any ideas would be greatly appreciated.
 
Thanks,
Anirban

[Wernerjb]

Hi, similar cells were used in the Ricoh 35 Elnicas, for example. I guess they were put in to increase both meter range and sensitivity.  
It turned out to be impossible to replace them by two single cells, that is why I gave up all attempts to repair the Ricohs. Besides, I could never find even one such three-pin cell, and that is why I never figured out about the wiring (which would have meant a complete knockdown of the board in the lens barrel), W.