Connect with us

Photocell Light Level Controls Bar Graph

Discussion in 'LEDs and Optoelectronics' started by DenisNH, Dec 3, 2006.

Scroll to continue with content
  1. DenisNH


    Dec 3, 2006
    Hi All. I'm new here and have been searching around for more information on this subject without much luck. If this has already been discussed, I apologize. I've always worked on a systems level and have done very little component level work, so my theory in that area is pretty rough.

    What I would like to do is make a basic light meter using cadmium-sulfide photocells available at Radio Shack. (Part# 276-1657) I would like to use the LM3914 bar graph driver with a 10 LED bar graph. The greater the light intensity, the more LED segments would glow.

    These photocells vary resistance rather than supply a micro-voltage, and this is messing me up a bit. The greater the light intensity, the LESS the resistance. The photocells are very sensitive, though, and I think they would do a great job if I can work them into the circuit.

    I've only spent a few hours on the circuit so far, but at this point feel that I'm spinning my wheels. Having just printed off a bunch of data sheets and application notes, I'm ready to go back to studying the available information before jumping back into the project.

    If anyone has pointers to web sites that explain this, or have any advice to offer, I will be very grateful. The LM391 seems like an awesome chip with a lot of potential!

  2. gravesend


    Jan 5, 2010
    intriguing question
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day