Connect with us

low voltage led for 3V coin cell

Discussion in 'LEDs and Optoelectronics' started by tbender54, Aug 18, 2011.

  1. tbender54

    tbender54

    3
    0
    Dec 31, 2010
    I made a simple timing device with Picaxe 20M2 that operates off 3V coin cell. I want to have a red or yellow led come on when voltage drops below approx 2.5V.
    It looks like I need a regulated supply to do this with Picaxe and thats out of the question.
    Is there any way to do this with a few external components - does not have to be super precise.Space is limited in the device.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,191
    2,692
    Jan 21, 2010
    There are voltage detector chips that will do this sort of thing. The only concern is that you're getting close to the forward voltage drop for a red LED, so it may not stay on for much longer if the voltage drops.

    Something like this may do the job. (note the outputs vary and I have not verified that this will drive a LED, it's just a suggestion for a class of devices.)
     
  3. tbender54

    tbender54

    3
    0
    Dec 31, 2010
    Thanks much.

    Thanks I'll give them a try - certainly cheap enough!
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,191
    2,692
    Jan 21, 2010
    Just make sure that you get one that can either source or sink current when the voltage drops below the set point. Some can only do this when the voltage rises.

    Like I said -- I didn't check.
     
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

-