Dynamite Blaster Box

While most “normal” people have never seen a blaster box in person, chances are that they’ve seen one on TV or in a movie.  Anyone who has ever seen a Roadrunner cartoon featuring Wile E. Coyote has seen one in action, although usually not with the intended effect.  For some examples in TV and cinema, click here.

The blaster box is a portable device that allows the operator to send a pulse of electrical current through a pair of wires to an explosive charge.  This is typically dynamite, TNT, or some other compound that is detonated using an electrically-fired blasting cap.  These are particularly common in mining operations, or military demolitions in the field.

The charge is typically generated by a mechanism that actuates a generator or dynamo.  This is essentially an electric motor operating “backwards”: the shaft of the motor is rotated using outside force, and this generates an electric current across what would normally be the input connections. This “outside force” can be a plunger pushed downward through a rack-and-pinion arrangement to cause the dynamo to spin, or with a spring-loaded action.  The device is rated on the basis of how many blasting caps it can set off in one shot (basically, providing enough current to heat the filaments in the serially-wired blasting caps sufficiently to initiate the explosion).