Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: lacanau on September 04, 2010, 08:33:43 PM

Title: LDR Issue
Post by: lacanau on September 04, 2010, 08:33:43 PM

Hi guys im building the 50 buck bot.

I'm currently trying to determine the resistor value for the LDRs.
However when I connect my multimeter and measure resistance, There is no change whether the LDR is in darkness or in light.

I have an analogue multimeter and 5 different resistance measuring values, I have tried measuring with every setting. The lowest setting is 1K and the highest is 200K.

What am I doing wrong? :(

Thanks  :D

Title: Re: LDR Issue
Post by: Soeren on September 05, 2010, 11:43:26 AM

Hi,

Hard to say what you're doing wrong, even if it is quite simple to measure an LDR

Are you sure it's an LDR you're measuring?
Are you perhaps shortening the wires somewhere?
Are you sure the probes are connected in the right sockets on the multimeter?

The difference in resistance of an LDR is very large from dark to light, so if regular resistors measure OK, it's either shorted wires or a broken pin.

What does it measure - high Ohms or low Ohms?