Abstract: A unit is disclosed for individually controlling power to multiple loads, such as lights. The unit has multiple phase control channels, each having thyristor control of current to the load, triggered by a ramp-and-pedestal firing circuit employing a unijunction transistor with a capacitor at its emitter. The system has a circuit providing a pulse to all of the firing circuits to discharge the capacitor synchronous with the AC line. Another circuit generates a sinusoidal compensating signal for all of the firing circuits.Each of the load channels has its own power control. In addition, a master control allows the power on all channels to be changed together, with the proportion of power in each channel set by its individual control.The unit is housed in a box having a base sheet shaped to form front, bottom and rear walls, with side walls attached at opposite edges of the base sheet.

Abstract: A circuit for linearizing the power output of a thyristor uses a threshold switch to pulse the thyristor into the conducting mode. An accumulating capacitor provides a current to operate the threshold switch. The current that charges the accumulating capacitor arises in a DC amplifier and absolute value of sine current source. The accumulating capacitor may discharge either through the threshold switch or through a shunt switch if the threshold has not been attained within a predetermined time period. The timing device for the shunt switch is a sync pulse supply that keys off the absolute value of sine current source.