I am trying to build a simple LED flasher circuit using 555 timer IC. Tried building it on breadboard and simulators several times but that is not working. As I am a beginner I think I am making some mistakes but with a lot of efforts I couldn't find that. Can some one please have a look to the breadboard circuit that I have build on simulator and tell me what is the problem in this circuit and why it is not working.

enter image description here

Here I have used 4k resistors between pin 6 and 7. and used 1k resistor with LED. Also connected pin 2 with pin 6 which is not visible in the image. Thanks

  • \$\begingroup\$ IC pin no 1 is ground pin You not connect ground \$\endgroup\$
    – Sameer
    Jun 23, 2023 at 1:32

1 Answer 1


I've got a few things for you to check out.

1) your breadboard power busses are not continuous. There is a wide spot in the middle of the breadboard. The power buses break in that wide spot.

2) color code for the LED resistor shows 500k. You say that you are using a 1k resistor. Try connecting the LED directly to the power supply via the resistor and make sure that it lights up.

Is this a CMOS 555 chip?

  • 2
    \$\begingroup\$ Up vote mainly for the bread board comment. A standard breadboard power rail splits half way through the length \$\endgroup\$
    – Passerby
    Mar 22, 2015 at 5:48
  • \$\begingroup\$ Thanks a ton. yes it was the breadboard issue. I used a jumper wire between two parts of the power rail and it works. \$\endgroup\$ Mar 22, 2015 at 6:07

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