Need useful ideas for a part

[Govmnt_Lacky]

Found some of these laying about in a drawer and I feel like they can be useful for some of the latest projects BUT, I am not savvy with LDRs so I am consulting the forumites.

CL705L/2

They are: LDR dual

Tech info:

Resistance @2ft-c = 7.5K
Min. Dark Resistance 5 sec. After 2ft.-c = 500K
Max Voltage = 100V
Spectral Response = 5500

Dual element Cell matched to <or= 20%

Any help would be appreciated. What can these be used for?

Thanks 

[Mark Hammer]

Assuming their rise/fall time is not too weird, they could be great for a phaser.

[Govmnt_Lacky]

I tried to measure the device but, I am not sure how to do it correctly. In the lighting I am in now, I can get down to 1K (really close to the lighting) and when I cover the LDR completely the resistance just keeps going up, up, and up!

I guess the DUAL function just lets it vary 2 different resistance in the circuit. So, instead of having 4 different LDRs focused on a lamp/LED you can just use 2 of these and it would be more accurate too 

@Mark: I didn't even think of a Phaser. I was thinking more along the lines of the highly debated UVICS or some form of Univibe-based circuit. Maybe even an Optical-wah.

[EATyourGuitar]

you can use it to control an APC or 555 oscillator etc.. since the APC works great on 500k or 1M pots. instant photo theremin. I drew up a schematic where the LED lights up when you play to decrease the resistance of a feedback loop for rock solid sustain with no dynamics.

[Govmnt_Lacky]

Very nice EYG 

I am a noobie to using LDRs and LDR circuits so this is all new to me. It is one of those situations where I only know enough to be "dangerous!" 

[EATyourGuitar]

think of it like a pot where the value of the pot is anywhere from 300k up to 3M but not exactly known until you measure it with a meter and a flashlight. the cheaper the LDR the greater the tolerance. you can get 300k and 1M in the same bag radio shack. not sure if they are different parts or just tolerance all over the place.

[Govmnt_Lacky]

think of it like a pot where the value of the pot is anywhere from 300k up to 3M but not exactly known until you measure it with a meter and a flashlight. the cheaper the LDR the greater the tolerance. you can get 300k and 1M in the same bag radio shack. not sure if they are different parts or just tolerance all over the place.

well, like I said above... I am not sure if I measured it correctly. The datasheet for this LDR says it is a 7.5K/500K on-off. However, in my lighting, it will measure around 2.5K (at sitting on my arse level) and when I cover it up (by hand or the likes) it will start to climb into the 2-3M ohm region and up 

Like I said, I do not know if this means it is a BAD ldr -OR- I am just not measuring it correctly as in adding/removing the correct amount of light.

[EATyourGuitar]

conditions on stage will never be the same as the lab. LDR's are only broken when the resistance doesn't change at all. if you look at LDR's with really nice specs (and tighter tolerance), you'll also notice that the price jumps from $0.10 up to $10.00 each. I'm fine with the cheap ones for a little wanky photo theremin that costs me $1 total to build.