Abstract: A low voltage dimmer is shown with the dimming function being on a primary side of a low voltage transformer. Live voltage feeds through a triac to the primary side of the transformer with the gate for the triac being controlled by a microprocessor. To prevent burnout of the transformer if the secondary load side is open, zero crossing of the incoming signal is determined by the microprocessor. If the time constant between the zero crossing of the live voltage and the charging of a capacitor with resistance being provided by the primary side of the transformer exceeds w predetermined time period, the microprocessor will be inhibited from generating a pulse to fire the triac. When the primary side of the transformer has been opened, the load on the secondary side can be re-established, i.e. light bulb replaced. Power for the microprocessor is from the charging of a capacitor used to provide the triggering signal to the microprocessor. Also the microprocessor may be triggered from remote locations.

Abstract: An electronic control circuit is disclosed herein for transmitting a coded signal and operating power to a selected one of a plurality of receivers via a single pair of wires. The control circuit includes a transmitter coupled to a source of AC line voltage and having a coding network for coding signals consisting of missing cycles from the AC line voltage so that a resultant output signal constitutes both the coded signal to the receiver and the operating power for the same receiver. Timing networks are included in the transmitter control circuit for allowing the output signals to be transmitted to the selected receiver only within a brief time interval. Reset networks are interconnected within the transmitter control circuit and the timing networks for returning the transmitter control circuit back to a condition of awaiting asynchronous commands for forwarding to a selected receiver via the single pair of wires.

Abstract: A soil moisture detector is disclosed herein for incorporation between a timer controller and an electrical water supply valve. The detector includes a pneumatic diaphragm apparatus whereby a pressure level is maintained or released between a pair of diaphragms in response to a moisture sensing valve buried in the ground. The pneumatic condition of the detector permits the slug of a solenoid valve, responsive to the timing sequence of the timer controller, to open or close a switch for supplying voltage to the water supply valve.