Centra-burkle Gmbh & Co.

Henning Becker

Gunther Weimer

Fritz Jauss

A system for the control of a load such as a heating or cooling plant in response to changes in an external parameter, specifically ambient temperature, comprises a loop circuit with two conductors connected at an input end across a power supply and at an output end across a switching network, the load being inserted in one of these conductors. A high-impedance voltage multiplier connected across these conductors downstream of the load, in parallel with the switching network, supplies the necessary operating voltage to a parameter sensor such as a thermostat even when that network is in a low-impedance state so as to draw a maximum load current. The switching network may include a voltage clamp provided with a source of reference potential, e.g. a primary battery, which upon failure of the normal power supply can act as a standby supply insuring continued operation of a timer serving for a periodic switchover between different temperature thresholds for the thermostat.

Load-control system with two-conductor supply circuit

A system for alternately activating and deactivating a load comprises a high-resistance d-c circuit branch connected across a power supply downstream of a load-operating impedance, this branch including a voltage limiter and a voltage multiplier in series with each other and with a switching stage responsive to commands from a timer and/or a parameter sensor such as a thermostat. The junction of the voltage limiter and the voltage multiplier is connected to one input of a differential amplifier whose other input is energized with either of two potentials, respectively higher and lower than that of the junction, by the switching stage. The amplifier output controls a variable-resistance element, such as a transistor of the bipolar or the MOSFET type, connected across the high-resistance branch to form a current path in series with the load-operating impedance, the resistance of this path being variable between a high value minimizing the flow of load current and a low value sufficient to maintain the switching stage operational. A standby source may be provided for keeping the switching stage or at least an electric timer thereof energized during interruptions of the main power supply.

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Schonaich, Germany

Henning Becker