Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Did I just fry my IC555 ?

  1. Dec 20, 2012 #1
    Did I just fry my IC555 ??????

    Hi, 1st time poster, long time student/hobbiest of math, physics, most sciences. Just getting serious about electronics lately so I made my 1st 555 circuit ever

    I made this blinker , it's a short vid with a very simple schematic in it, he draws it as he goes towards the end. I'm using 5V from an old printer PSU, I used 2 series of 2x 4.7kΩ, the circuit only uses "capacitance" in one place.

    I had it working fine and I was trying different capacitors and series/parallel caps.

    Then I put a 33kΩ between the neg side of the single cap and pin 1 of the 555 (should of had it before the cap to make a little RC series), and it blocked the current almost completely.

    So I took it out and now the circuit won't blink anymore. If I place a short where the cap goes (between pin 1 and 2) the LED lights up and says on. But if I use a cap, the LED lights up for the correct amount of time, but never comes back on. Then if I reverse the cap (not ideal I know), the LED will light up for the correct time.

    So I can get the LED to light for the right time, but it never comes back on.

    The resistors all still measure correctly, so what happened?
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Dec 21, 2012 #2


    User Avatar

    Staff: Mentor

    Re: Did I just fry my IC555 ??????

    Replace the IC. If the new one works where the old one wouldn't, I leave you to draw your own conclusions ..... :wink:
  4. Dec 21, 2012 #3
    Re: Did I just fry my IC555 ??????

    only 1 I had, I made another 555 circuit and it doesn't work right either

    So I'll have to make some 741 circuits, at least I have a few of them
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook