Abstract: A relay control circuit which is capable of reliably controlling the transmission of electrical power in very small time increments. Specifically, the present invention features a proportional firing circuit which will create an SCR firing signal whose pulse timing is proportional to the magnitude of a variable input signal. The control circuit varies the conduction time for the SCRs by varying the time between firing signal pulses of fixed duration.

Abstract: A strain measurement device to determine the amount of clamping force or pressure developed in a machine from the small amount of linear movement which results from strain on a predetermined part of the machine, such as a tie bar. The strain measurement device features an elongated arm which will pivot in response to such strain movement and amplify or magnify the amount of this strain movement. The strain measurement device also includes a sensing unit which will measure the amplified strain movement, and a circuit for converting this measurement into a signal indicative of force.

Abstract: A multiple phase electricity switching apparatus having electrical components arranged and mounted on a heat sink structure which having the same external dimensions as a conventional electromagnetic relay. The switching apparatus controls the amount of electrical energy passing therethrough and into electrical resistance heating elements thereby controlling the temperature of the molten plastic raw materials. The switching apparatus includes a pair of inverse parallel connected SCR's (silicon control rectifier), a photo coupling, and a zero cross switching circuit. The SCRs are separately mounted on and separated by a structure having two parallel members. The electronic circuit components permit the electrical power supplied to the load to be switched more frequently thereby realizing improved temperature regulation.