I'm trying to find a modern alternative for a discontinued photocell (a Clairex CL5M4 CdSe photoresistor.)
Its datasheet gives the following:
Illuminated resistance 1.5k @ 2ft-candles
Min dark resistance 400k @ 2ft-candles
Max voltage 250V
1: I believe 2ft-candles ≈ 21 lumen, but modern photocells are rated at 10 lumen.
How do I convert the given resistance to 10 lumen? Maybe (1.5k / 2.1 = .7k)?
But the light source will appear brighter when closer, so maybe (1.5k * 2.1 = 3.15)?
2: Modern photocells give Illuminated Resistance as a range, ie. "0.5 ~ 17kOhms".
How do I choose an appropriate photocell if I only have a single number as shown above?
3: How can I use a multimeter to measure the voltage applied to the Clairex photocell?
Any help would be greatly appreciated!