#783 555 Delay On

A simple 555 circuit that provides a power-on delay.

Notes

This circuit provides an output (pin 3) that does not go high until some time after power is applied. Adjustable from 1 second to 2 minutes. One can find variations of this circuit in many places, for example:

• Delay Before Turning On on Talking Electronics

Circuit Design

Designed with Fritzing: see DelayOn.fzz.

Testing

With the resistor set for a pretty short delay, I’ve captured the on-sequence with an oscilloscope:

• CH1 (Yellow) - 555 output (pin 3)
• CH2 (Blue) - power rail

Credits and References

• LM555 Datasheet
• Reference Circuits:
  • Delay Before Turning On on Talking Electronics