An interesting timer

[chemwarrior]

Ive discovered a highly interesting timer. What it is is a mason jar that has a piece of metal that is cut to fit snugly inside the jar, but will allow it to move with relative ease. The lid must be a plastic one that has had 2 nails punched through it. (You connect the leads to it.) Once that part is done, then you get some dried peas and place them in the jar. You then fill it with some water. Place the piece of metal on top of that then place the lid on it. the piece of metal will contact the nail and comlete the circuit. Im not completely positive if this will work(I got the idea from a friend) but it was interesting and I felt this was the perfect place to put it up. Any ideas or comments on how it could be made better would be appreciated.

[mongo blongo]

I suppose it could work but it's incredibly crude! You can never be sure of the exact time delay! What happens if there is an emergency that means you have to switch it off? The pigs could be near by or something and you won't know when it could go off so you can't go near the device to switch it off.

[chemwarrior]

Actually, you can be relative sure of the time by figureing out the rate of expansion the peas take. I know its crude, but I figure it could be of some use when testing things and you dont want to wast a more valuable timer.

[A43tg37]

The only problem is that all peas will expand differently. Even within the same bag, the expansion rates could be different, and even if they were the same for one bag, using a different bag when the first was empty, or even using different water temperatures, could cause differences in expansion times. Probably not dramatically, but even a few seconds difference in expansion could cause a lot of trouble in explosive timer applications. It seems like a very unreliable timer to me, and I'd rather resort to a cheap electromechanical timer (which is still way more relaible and predictable than the dried pea timer) for simple test applications. And if I was compelled to make an expansion timer, instead of peas, I'd use several stacked-up sponges (certain kinds of sponges-the ones using as wipe sponges on many soldering irons come to mind-they expand dramatically when they get wet, but do so at a steady enough rate to be somewhat predictable). Oh, and your friend probably got this idea for a "dried pea timer" from either the Improvised Munitions books files online or the terrorists' handbook or Jolly Roger crapbook (yech-I hate to even mention the last two on here), and we all know how reliable those (the latter two) books are.

[hodehum]

Actually he may have got the idea from “CIA Improvised Sabotage Devices” (page 15)
It says that in the case of dried peas it usually takes to expand usually ranges from ½ to 2 hours to expand. Which is just far to inconsistent for my liking.

But I would have to agree with A43tg37 that there are far better alternatives available that a lot more accurate.

[Mick]

well, given the purpose of a timer. i don't think it would matter if coppers were around.
i mean the whole idea of timer is so it detonates when your not there, and someone else is.

frozen peas seems a little dodgy is my book.

much easier to use a small alarm clock and a 9v relay.

[NoltaiR]

Though most of the HEs in crapbooks are really crap, much of the simple 'common sence' devices are credible... the reason being that they are virtually always plaguarized procedures from army manuals and various other research books.

But in any case, dried seed timers powered by osmosis are one of the oldest ideas in the book, and in my opinion are far too crude and plain to be discussed in a forum of this caliber.

<small>[ September 09, 2002, 01:35 PM: Message edited by: NoltaiR ]</small>

[xoo1246]

I have read it in various manuals too, and I wouldn't use it unless nothing better was at hand. Very crude indeed.

[sinstar]

I remember when I was just starting out, I would always use really shitty unreliable stuff like that, one time I even used that cloths peg delay(you know you use the jaws as electrical contacts and wrap solder around the legs of it)on a large cheddite charge, its just a bit annoying having to sit around for like 20minutes before it goes off, and if some technical problem accurs you know that you have to go and reset it(as opose to leaving it for some poor little kid to find).

[NoltaiR]

I do, however, like the idea that sinstar speaks of.. its another one that can be found in the crapbooks but when used for trip wire ignitions, I find it to be very simple yet somewhat perfect for the use in the improvised battle field in which only the most basic of devices reign as the most devestating.

[SATANIC]

yeah, a little crude, especially by the standards that are usually upheld here, but you never know..... in some third world country it may be quite useful.....

and i must say, it's one of many assorted ignitor / improvised switch devices that pop up from time to time, but some of them are quite useful... like the spoon and clothes peg one, it does make the perfect tripwire, especially when you have ration pack spoons around....

but it can be said that with a little imagination, much better ways can be thought of... all you have to work out is how to get two wires to touch..... :rolleyes: