I've attempted to set up a 556 timer on a breadboard. I bought two 556 timers because the project I will be using it in requires 3 timers, and I wanted to be cost effective.

I have followed a tutorial online about how to wire it on a breadboard, and for right now I am only using one of the timers on the 556 chip. Unfortunately, there is no output going into the LED, i.e it isn't flashing like it should be. I've read the data sheet, turned my LED and capacitor around, and tried a second chip that I have. No luck so far

Have I wired it incorrectly, or did I just have bad luck and end up with 2 busted chips?

Thanks for your help

Here's a picture of my breadboard: 556 on breadboard

Link to 556 datasheet

  • \$\begingroup\$ (a) Unfortunately, in that photo it is not possible to clearly see all leads on every component, to identify where they are connected. Providing a clear schematic diagram would help, but even then, since the breadboard construction might not match the schematic, we need a photo from you where all leads are visible. (b) I'm especially concerned about your LED connected to NE556 pin 9, as it looks like both LED leads are connected to the same horizontal row 58. If they are, then that won't work as you expect. Please clarify exactly how the LED and its resistor are wired on your breadboard. \$\endgroup\$
    – SamGibson
    Oct 11, 2017 at 5:25

1 Answer 1


Even if the picture is not very clear I can guess you're trying to implement the classic astable circuit, using timer 2.

enter image description here

enter image description here

However, I find the following issues:

  1. You are not connecting the reset (pin 10) to VCC (even if internally is connected to the base of a PNP transistor, so leaving it open might not cause a reset).
  2. The LED is likely connected to the same row (unless you soldered the resistor to its cathode), but we cannot see this from the picture.
  3. The capacitor has its negative terminal toward threshold and trigger: the negative terminal should go to GND.
  4. Maybe is not shown, but from the picture we cannot see if you are connecting the ground (blue line) of the right part of the breadboard, to the ground of the left part of the board.
  • \$\begingroup\$ Thanks so much for your answer, you were right, the capacitor was oriented the wrong way and I put both LED leads in the same channel. Can't believe I made such a dumb mistake! \$\endgroup\$
    – DylanG
    Oct 11, 2017 at 5:56

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