Speaking of CDS cells...do they go bad? And if so, what are the options
besides a handheld meter, which is always de riguer anyway, IMO.
Earl
*********** REPLY SEPARATOR ***********
On 10/24/2003 at 11:36 AM Moose wrote:
>lamadoo@xxxxxxxx wrote:
>
>>My wish: simple mod that allows pre-fire, putting camera in
>"hair-trigger" mode. Another press would send the rest of the process in
>motion.
>>
>You would not be able to judge the moment through the viewfinder, as the
>mirror would be up. What I'd like is a second self timer mode with a 2-3
>second delay, that 12 seconds gets kinda long when used repeatedly.
>
>>Anyway, I'm thinking that one of the 70s rangefinders will be a fine
>concert camera: very fast lens near 40mm, quiet, and very sharp. I may
>have to buy/reject/sell several to sort out an outstanding example before
>I rebuild it. I'm reading with great interest the various ideas about
>converting from mercury to silver batteries. Once I find the example with
>a sharp lens, I can tune the poteniometer rather than install a diode.
>Does anyone have links to ideas about upgrading from a 70s era
>cadmium-sulfide cell to a silicon-blue one? If I'm adjusting a pot
>anyway...
>>
>>
>CDS cell generates its own current to drive the meter. Si-blue is a
>light variable resistor, so it needs a power source. You would have to
>determine full characteristics of the meter movement and design a
>circuit to generate the correct voltage and current range across the
>coil resistance. Then, of course, you have to figure out how to mount
>the cell and where to put the rest of the circuit. I used to be up for
>this kind of project years ago, but no more.
>
>Moose
>
>
>
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