LED Green and RED Random Light generator

Thread Starter


Joined Apr 28, 2012
Good day

I need to make a basic hand held unit that once you press a button 2 LED's will flash simultaneously and then randomly select either the red or the green LED.

I need some guidance as to what IC to use so I can begin to research it and try and build it.

Many thanks


Joined Apr 7, 2016
I have a quick cut and paste idea, with only a chip:
When the button is not pressed, R1 and R2 will hold the capacitor C1 voltage on the half power supply, thus stopping the oscillator in the state it has reached.

To get a good symmetry between the two LEDs, I use the Discharge output (U2.7) and diode D1 to switch between LEDs.
But for best, non adjusted, symmetry I would probably choose a CMOS version of the 555.

If the switching rate is to be changed, select the same value for R1 and R2 and set them to be at least 10 times the R3 value.