Turn a timer into a bomb timer
A really simple project to have fun and play cops and thieves. For educational and fun uses only.
To have a bomb timer, you need two things.
1. To get sure that nobody can cut the cables or open the case and check the circuit.
2. You have to trigger a relay when the buzzer beeps in the end of count-down.
1. You put more than two cable connecting the timer and the trigger. This way, nobody can know which cables to cut. You take two cables and connect them in the case, in a way that if the case opens, they disconnect. In the other side of the cables (trigger side) you check the connection of these cables with a relay normally close. If its power is cut off (by cutting the cables or by opening the case) the relay closes and the trigger goes 'boom'.
2. You connect two cables to the buzzer's connections, that is in parallel. When the buzzer beeps, you get a voltage in your cables. You make a flip-flop circuit to avoid close-open-close-open (this happens when beep-beep-beep). Finally you drive a relay from the ff output. Simple but a little tricky too.
The timer is a simple gadget you can find in your local RadioShack shop.


