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Led flasher 555 delay-off help!?

I have a working 555 flasher circuit:  http://www.555-timer-circuits.com/flashing-led.html - i have added a switch between the + and the board, and replaced the R2 with a variable. Works great!

Now i would like to add a "delay-off" function, if thats what it is called, so a single activation gives 10 seconds of flashing.

So, any advice?

PS: I have pnp & npn's, resistors etc, but no relay's.

Thanks fella's!

frollard5 years ago
You need to replace the switch that powers the board +, with another 555 timer (or the other half of a 556). The first stage needs to be in 'one shot' or 'monostable' mode where it stays off, when activated with a pushbutton stays on for 10 seconds, then goes back to stable off.

http://www.555-timer-circuits.com/operating-modes.html shows monostable mode that you would use for the first stage.
http://www.bowdenshobbycircuits.info/page9.htm#555mono.gif