Is it possible to build a circuit where it constantly turns a component on and off with transistors? I heard that a NOT gate loop does something similar but I cannot figure out how to build a NOT gate loop that does exactly that.

I've tried with an online circuit simulator and had gotten a LED to turn on but the LED would not turn on and off continuously.

Here's the simulation

Any help will be appreciated

Btw if anyone wants to edit the circuit, after you've finished you have to press file>export as link

Thanks for all the help, turns out I went in the completely wrong direction.

I tried the astable multivibrator circuit and it worked!

The circuit

  • 2
    \$\begingroup\$ google "astable multivibrator circuit" and look at image results. \$\endgroup\$
    – The Photon
    Apr 3, 2017 at 1:52
  • \$\begingroup\$ It needs to be Schmitt triggered. Or it won't work. \$\endgroup\$
    – Bradman175
    Apr 3, 2017 at 3:26

1 Answer 1


There is the Uni-junction Transistor like(2N2646) configured as a Relaxation Oscillator. The timing can be set with emitter side components using the usual RC time R/C calculations for output load controlling the on/off stages. The time period of the oscillation T2 and the discharge time T1 can be configured with components but you have to make sure that the resistance is not too high or too low or the oscillation or trigger will not happen. Schematics can be found for these. Good luck.


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