Improvised Explosive Devices, Radiological Dispersal Devices and Chemical Dispersion Weapons usually contain some type of time delay device. These are grouped together under the common name, “timers”—no matter how they function. Some are combination types, operating on more than one principle.

We incorporate timers in many of our inert IED training aids. Some are mechanical as in windup alarm clocks and kitchen timers. Others are digital countdown types with display screens. Some use electronic circuitry that is pre-programmed to several specific set delay times. Others are mechanical, and some are mechanical/chemical combinations.

Timers may be used to initiate (detonate) an IED at a specific time. They may also be used by the bomber for delayed arming. This allows time for setting up and wiring together all of the components, and transporting the IED to its target location.

Delay arming timers allow for boobytrap devices to be set up, with no hazard to the bomb maker until they have timed down to zero. Delay arming timers are an “open switch” for the other component and initiating devices in the IED circuitry while they are quietly counting backwards to zero.

We make some timers that function based on a lit cigarette, a candle, a mousetrap and solder, the dripping of water, beans and other seeds germinating, etc. Some of these devices have been used for almost 100 years in different parts of the world, to provide time delayed arming, or detonation. They have an equal place in setting off delayed arson devices.