Ronald N Ziegler Deceased505 Brochardt Blvd, Knoxville, TN 37934

3972471, Aug 3, 1976

May 27, 1975

5/581285

Ronald N. Ziegler - Wescosville PA

G05D 2330

236 46R

An automatic temperature setback system for controlling a heating unit includes the use of two devices. One device includes a oscillator circuit which is actuated by a timer control. The oscillator circuit can be an astable or free-running multivibrator. The output from such device is coupled across the low voltage secondary transformer winding of a typical heating system control unit so that, at specific timed intervals, the low voltage (i. e. , 24 volts RMS) can have high frequency modulations superimposed upon either the positive cycles of such voltage or alternatively the negative cycles or alternatively both cycles. Such one device could be termed, in general, means for half-wave modulating the low alternating voltage carrier from a typical heating system control unit. The low voltage wires from the typical heating system control unit, in a conventional household, are coupled through the house to a low voltage thermostat located in one of the rooms of the house. The second device of the system includes a module, herein termed a thermostat module, which is activated by the modulation in the low voltage wires which are coupled to the thermostat.