Connect with us

Bleeder resister size

Discussion in 'General Electronics Discussion' started by colum, Oct 10, 2013.

Scroll to continue with content
  1. colum

    colum

    155
    4
    Jul 25, 2013
    I want to put a resister accross a DC supply leads to discharge the voltage in the capacitors. This will be only used to discharge after each useage. I expect the voltage to be from 1 to 125v DC and the amperage to max of 3 amps.
    I checked all of my books and the internet and I could not find any info on size and from my limited knowledge I understand you should not discharge a cap too fast...Thanks...colum ( I its too late to put an internal res accross the cap)
     
  2. davenn

    davenn Moderator

    13,866
    1,958
    Sep 5, 2009
    from what I have seen across big caps in amplifier PSU's running at ~ 50 to 70VDC something up ~ 10k , 1/2 Watt would be OK

    cheers
    Dave
     
  3. colum

    colum

    155
    4
    Jul 25, 2013
    Thanks Dave
     
  4. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Sorry, Dave, but at 125V a 10K resistor will dissipate 1.6 Watts. A 1/2 W resistor ain't going to make it.

    Bob
     
  5. colum

    colum

    155
    4
    Jul 25, 2013
    Hi Bob. Since this is just for bleeding a capacitor thats disconnected from the power supply would it make a difference and would a permanently installed bleeder require different ratings..Thanks...colum
     
  6. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    If the resistor is connected all the time, it would have to be at least 2W. If you only connect when it is powered off, I suppose you could get by with less.

    Bob
     
  7. davenn

    davenn Moderator

    13,866
    1,958
    Sep 5, 2009
    OK so up the wattage rating a bit :)

    D
     
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

-