Remote Control

Some effects can be operated locally (shelves and pictures can be dropped by removing nails or supports from behind). Others have to be controlled from a distance.

Electric ignition

A novel method of releasing something can be achieved by using one or more pyrofuses (page 112) and a nylon drop line.

The item to be released is tied to the nylon line, which passes through a transverse hole in a short length of metal tube. This tube has a diameter sufficient to accommodate a pyrofuse, which is positioned with its head against the line. A small plug of paper is inserted to trap the spark and retain the heat.

Firing the pyrofuse causes the nylon to melt and release the load. A priming of gunpowder is needed for heavy lines.

Solenoids

Electrically energised solenoids are useful devices for remote control, but they consume a great deal of current and have only a short operating travel. For most efficient use they should be incorporated in mechanisms where they release levers, these taking the weight or the strain. A typical example is shown for a dropping box.

Bowden cable

A stranded steel cable in an armoured sheath can be used for pulling things. For light work it will also push, but generally push/pull motions are achieved by employing a return spring. A cable of this kind can also be used for light rotational movements (the movements of dials or the hands of a clock).

Pneumatics and hydraulics

A plastic tube with a balloon fixed at either end can act as a remote-control device for certain purposes. Before being fitted, one of the balloons is inflated to its full capacity so that when released the air pressure equalises, half inflating both balloons. When one balloon is squeezed the other expands – useful for breathing dummies and pulsating nasties.

Two bicycle pumps can be connected to perform in a similar fashion. Filled with water or oil they will transmit considerable energy.

Professional air-control equipment and hydraulic systems can be purchased from commercial manufacturers or hired from theatrical property suppliers.

REMOTE CONTROL

Remote control devices must be simple and foolproof.
1. Bomb release type with sideways-opening jaws (b). 2. Release using lever attached to solenoid (a) to hold the heavy weight. 3. A nylon line passing between two holes in a metal tube is severed when a pyrofuse is ignited close to it. a, Nylon line, b, Metal tube, c, Plug, d, Pyrofuse.