Author Options:

Flashing led? Answered

I know this may be basic but im still pretty new to this all. I have 4 leds that have to flash together. Would a 555 timer work? could someone link me to a diagram. I was wondering if i could make the speed change able, super fast to slow.

3 Replies

icengBest Answer (author)2012-04-18
rickharris (author)iceng2012-04-19


The 555 works by comparing the voltage on the capacitor with an internal reference.

The rate at which the capacitor discharges controls the time the output is on.
As the discharge of the capacitor happens through pin 7 via R2 then R2 controls the rate - Bigger slower smaller faster. There are formula to calculate available on the 555 data sheet.

Pin 2 starts the process pin 6 monitors the voltage. Pin 3 is the output.

To change the speed make R2 a variable resistor.

Radical changes may call for a change in the value of C 1 - you can switch in different values. Bigger slower smaller faster the value isn't critical except in relation to the speed on/off.

Select as Best AnswerUndo Best Answer