I had this idea for a buoancy timer. Back on totse, some people came up with the idea to use two close pins held apart, with wires attached, so that when they closed, the wires would connect, completing a circuit and heating a light bulb filament which ignites an explosive charge. When held open, the close pin is frozen in water. So once the water melts, the pin closes and the explosion occurs. Problem is that this is not very predictable especially in cold weather. Using a similar concept, a hole can be poked in one container(container A), with a small weight in it, so that once the container that container A is sitting in (container B) is filled with a fluid, container A gradually sinks, allowing wires to touch and complete a circuit. This can be used with a liquid that doesn't easily freeze, so it's much less affected by temperature. Very precise and predictable timing. Easy to put together. Yep, some people will say 'omgzbongoz bombs r bad' and it's a "kewl" idea. That's why I'm posting it here. Where all the other shitty messed up ideas go.
EDIT: container B can obviously also be the only one with a hole in it. That may work better. Pull a thumb tack out of it or something and pour water or whatever liquid up to a certain level. Thumb tack is likely to take forever though unless there's sufficient weight in container A to force water out. You'll have to adjust it to get the right timing.
Originally posted by Narc
Yeah you know water conducts electricity tho right?
Myself and other totse members had tried the ice timer. Works quite well. I scared the shit out of my brother once by attaching one to some fireworks, left it in the barbeque pit and forgot it was there. He took a nap in the hammock and it went off while he was asleep. He was convinced I was outside sneaking around messing with him and it was dark. I explained to him I had forgotten about it. It was a hilarious coincidence... As someone pointed out, you'll need more power for the water's conductivity to be a problem. Much bigger battery required. Use a 9 volt and you're good, but if it's cold enough outside, it may take forever to melt, and then possibly drain the battery, so you'll need a fully charged battery.
Originally posted by Narc
You wanna risk your life on that?
It's not dangerous at all with the ice timer, so long as you're using the right filament. You'll need quite a bit more juice going through it in order to get the filament hot enough to ignite a pyrotechnic mix or primary. You can test this out by not attaching any pyrotechnic mix or primary, and put your fingers on the filament. You won't feel any noticeable heat. Try a thermometer if you want to be sure. Brake light bulb + 9 volt battery. Gun powder for example, is going to take quite a bit more heat than anything you'd get with that small amount of current flowing through the ice. Certain primary explosives are quite heat sensitive compared to others, but even those aren't going to be a problem. If you're really paranoid, attach a length of fuse to the filament, and first check with thermometer.
Originally posted by aldra
electronics are so simple and cheap to come by nowadays it'd be easiest to just run an egg timer's alarm pins to a relay. if you want to use a mechanical timer an old trick was to attach contacts to the hands on a clock so that the circuit completes when they touch, or I guess putting contacts into an hourglass (filled with conductive powder) so that it completes when it fills to the point where the pins are
Everyone already knows about those methods though. The purpose of this is just mostly something new, which doesn't leave as much evidence.