Abstract: Pressurized gases supplied to a load device such as metal flame cutting torch includes separate dome regulators for each gas supply. Each regulator includes a pressure responsive input chamber connected to the corresponding supply by a supply solenoid valve. A second solenoid valve connects the input chamber to the discharge side of the dome regulator. A pressure transducer senses the output pressure of the regulator and develops a feedback signal which is compared with a reference signal in a differential amplifier to generate an error output signal. The reference signal may be manually set or be derived from a programmed numerical control, a tape control or the like. The valves are totally opened and closed. Restricted orifices are connected downstream of the solenoid valves to permit soft changes in the load gas flow. In an oxygen gas cutting control, a separate adjustable orifice provides for controlling the piercing rate.

Abstract: An ambient room illumination responsive control automatically changes the setting of a thermostat with ambient illumination. A thermostat has a pair of temperature responsive switches connected in series with control leads and a controller to low voltage A.C. power. A bypass relay has contacts connected in parallel with one of said switches. An illuminating sensor has a photoresistor in series with a resistor connected across leads with a common node connected to the gate of a controller rectifier. A capacitor timing unit is connected in one embodiment to produce a pulsed input. The rectifier is connected in series with a winding of the bypass relay and the timing unit across the thermostat leads. The rectifier conducts to open the relay contacts and insert the second switch in circuit. A second relay winding is connected across the control leads in series with a diode and a timing network to reset the relay and close the contacts.