How to limit range of LDR?

Started by blockhead, October 04, 2005, 02:48:24 PM

Previous topic - Next topic

blockhead

Hello fellow pedal enthusiasts,

I am trying to figure out how to limit the range of an LDR.  Google has not been useful, and it seems to me that there has got to be a way to do it easily.  Perhaps a 1M trim pot in parallel?  The results on the breadboard were not promising, though.

Any suggestions?

Thanks in advance.

BH

Pedal love

#1
If you put a 3.3k resistor in parallel with the ldr and a 3.3k in series that would be limiting to 6.6k at one end and a little over 3.3k on the other end. Of course you could choose your values.pl

blockhead

PL,

Thanks for the reply!  I will try it out on the breadboard tonight.  I am trying for a total range of 250k, so your example really helped.

Much obliged,

BH

Pedal love


blockhead

Quote from: Pedal love on October 06, 2005, 12:12:05 AM
Cool! Please post how its working.pl

Pedal Love,

Originally, the LDR was ranging from a few hundred ohms to about 1.6M.  I did a quick check with the first pair of resistors that I found on my bench; 8.2k. 

I used one resistor in series, and the other in parallel, and tested the LDR under the same light/dark conditions.  The range was now limited to 8.2k on the low end, and 11.7k on the high end.  It wasn't exactly what I expected, but with a little tweaking (and resistors in the correct range), I am sure that I can dial in the range that I will need. 

Thank you for your help!

BH

Pedal love

You're welcome. I repeated everything and the results were 16k and 8.25k. Anyway hope everything turns out. Peace.