Timer delays, or "time bombs" are usually employed by an individual who wishes to threaten a place with a bomb and demand money to reveal its location and means to disarm it. Such a device could be placed in any populated place if it were concealed properly. There are several ways to build a timer delay. By simply using a screw as one contact at the time that detonation is desired, and using the hour hand of a clock as the other contact, a simple timer can be made. The minute hand of a clock should be removed, unless a delay of less than an hour is desired.
___________________________________ to igniter from | | igniter | 12 | : : | 11 1 | : : | | : : | 10 2 | : : | o................|......: : | | : | 9 3 | : | | : | | : | 8 4 | : | o.........|...... : | 7 5 | : : | 6 | :.+.....-.....: |__________________________________| __|_____|
| |
| battery |
o - contacts | |
..... - wire | |
|___________|
This device is set to go off in eleven hours. When the hour hand of the clock reaches the contact near the numeral 5, it will complete the circuit, allowing current to flow through the igniter or squib.
The main disadvantage with this type of timer is that it can only be set for a maximum time of 12 hours. If an electronic timer is used, such as that in an electronic clock, then delays of up to 24 hours are possible. By removing the speaker from an electronic clock, and attaching the wires of a squib or igniter to them, a timer with a delay of up to 24 hours can be made. To utilize this type of timer, one must have a socket that the clock can be plugged into. All that one has to do is set the alarm time of the clock to the desired time, connect the leads, and go away. This could also be done with an electronic watch, if a larger battery were used, and the current to the speaker of the watch was stepped up via a transformer. This would be good, since such a timer could be extremely small. The timer in a VCR (Video Cassette Recorder) would be ideal. VCR's can usually be set for times of up to a week. The leads from the timer to the recording equipment would be the ones that an igniter or squib would be connected to. Also, one can buy timers from electronics stores that would be ideal. Finally, one could employ a digital watch, and use a relay, or electro-magnetic switch to fire the igniter, and the current of the watch would not have to be stepped up.
4.33 CHEMICAL DELAYS
Chemical delays are uncommon, but they can be extremely effective in some cases. If a glass container is filled with concentrated sulfuric acid, and capped with several thicknesses of aluminum foil, or a cap that it will eat through, then it can be used as a delay. Sulfuric acid will react with aluminum foil to produce aluminum sulfate and hydrogen gas, and so the container must be open to the air on one end so that the pressure of the hydrogen gas that is forming does not break the container. See diagram on following page. _ _
| | | |
| | | |
| | | |
| |_____________| |
| | | |
| | sulfuric | |
| | | |
| | acid | |
| | | |---------- aluminum foil
| |_____________| | (several thicknesses)
|_________________|
The aluminum foil is placed over the bottom of the container and secured there with tape. When the acid eats through the aluminum foil, it can be used to ignite an explosive device in several ways.
1) Sulfuric acid is a good conductor of electricity. If the acid that eats through the foil is collected in a glass container placed underneath the foil, and two wires are placed in the glass container, a current will be able to flow through the acid when both of the wires are immersed in the acid.
2) Sulfuric acid reacts very violently with potassium chlorate. If the acid drips down into a container containing potassium chlorate, the potassium chlorate will burst into flame. This flame can be used to ignite a fuse, or the potassium chlorate can be the igniter for a thermit bomb, if some potassium chlorate is mixed in a 50/50 ratio with the thermit, and this mixture is used as an igniter for the rest of the thermit.
3) Sulfuric acid reacts with potassium permangenate in a similar way.
4.4 EXPLOSIVE CONTAINERS
This section will cover everything from making a simple firecracker to a complicated scheme for detonating an insensitive high explosive, both of which are methods that could be utilized by perpetrators of terror.
4.41 PAPER CONTAINERS
