You can use this to detonate a sonic grenade, firework, lights, anything! Super cheap and reliable, $5 project.

Step 1: Get Your Materials

-Depending on what you want to do, I suggest you pickup an alarm clock (with sound) or kitchen timer. Both were $1 at Dollarama!

Step 2: What to Detonate?

I picked up a 90dB window alarm, and was going to use that for a sonic grenade, then I found a 105dB personal alarm, and decided it would be better!

Step 3: Building.

-This is where the fun starts, smash open the clock and the and locate the wires running to the tiny alarm speaker.
-This will be a low voltage out put so you will have to connect those wires through a relay to allow a higher voltage (usually 4.5V) to be sent to the personal alarm. otherwise it will not be loud enough.
-Carefully smash open the alarm (you will need to preserve part of the case, because the speaker needs to vibrate in it to amplify the noise)
connect the wires to the alarm speaker to the relay (note the correct polarity)

This is pretty much it, set the alarm clock to go off at a certain time, and its output will be sent to the relay, which will set off the alarm!!! This makes a great alarm clock for someone that doesnt like to wake up!!!

Step 4: Optional

Of course you could have used the timer if you wanted to make a count-down detonater... and instead of an alarm at the end of the relay, how bout an explosive?

Get some nichrome wire, and thread it through a safety fuse, and connect the wire to the relay, for a more detailed how-to on electrical igniters visit UN: http://unitednuclear.com/wire.htm