Off-topic electronics question

[kristoffereide]

Hello.
I've been assigned this project from my airsoftclub:

I need to make a "bomb simulator", and this would be a timer that counts 3minutes and has a signal output and two led-outputs.

Can anyone tell me how to make this?
The signal-out would be connected to a smokedetector for loud sound and the two led-outs to green and red leds (ok and bang-mode)

Any answer would be of great help!

Just a timer-circuit would be great, the rest I can make myself. No need for signal-makeup or thinking about noise. There would be no input, just a counter to a relay

[frequencycentral]

Google for some NE555 circuits, that will do the job.

[Sir H C]

With a divider/counter to make a reliable delay of that long.

[kristoffereide]

With a divider/counter to make a reliable delay of that long.

Could you be more specific? A counter other that the 555?

[frequencycentral]

I think he's suggesting using the 555 as the timer and using a CD4024 or similar to divide the output. that allows you to run the 555 faster, and is therefore more accurate. If accuracy isn't an issue the 555 should do it on it's own with a suitable timing cap.

[kristoffereide]

thanks! I'll get experimenting