Quick question on photocell/photoresistor/LDR -- whatever you want to call it

Started by David, November 16, 2007, 03:55:57 PM

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David

I've been doing "mental design exercises" of a volume/wah pedal that uses the tone god's "Rock'n'Control" as its guts -- with the exception that I want to use a mechanically-darkened LDR as the front end.  I'd like the LDR to be 100K in full dark and the light resistance to be as near zero as possible.  Now, some of the LDRs I've seen are calling 10K to 50K low!  To me, that's hacking out a good chunk of the useful range.

Does anyone have any insight on information sources to lower the light resistance?  I'd like to get the lowest resistance I can so I can create a volume pedal that goes silent.

Mark Hammer

A)  Many commonly-available LDRs have "on" resistances of less than 1k.

B)  There is nothing that says you can't parallel more than one photocell or a photocell and a fixed resistor to achieve very low resistances.

C)  Most filter circuits can be re-tuned (via cap choice) such that vaiable resistances that do not descend below 10k still provide the full desired range of control. You may not have the component values the schem indicates, but you canstill have the performance that schem is intended to provide.

bumblebee