Control circuit for providing time selected application of A.C. power
AssigneeMinnesota Mining and Manufacturing Company
InventorsJohn H. Lee, Peter A. Lind
Life of this patent
Estimating the term…
Abstract
A solid-state programmable control circuit provides multiple time selected application of A.C. power to one or more utilization circuits or devices. The control circuit uses a crystal controlled time base generator which is synchronized to commercial A.C. power. Stand-by battery power is provided to maintain timing when A.C. power is lost. A time display plug-in module is used with the circuit for setting the time for the control circuit. Programming can be done at a point remote from the control circuit.
Claims9
A control circuit for providing time selected outputs of A.C. power including:
- an A.C. powered D.C. voltage supply;
- a solid-state, 7-day, 24-hour clock connected to said D.C. voltage supply and operative in response to timing pulses and having time indicating outputs;
- a crystal controlled time base generator connected to said A.C. powered D.C. voltage supply and connected to said clock for providing timing pulses to said clock;
- means responsive to A.C. power and operatively connected to said time base generator for providing a pulse for each cycle of A.C. power to said time base generator for synchronizing the operation of said generator;
- programmable control circuitry having a control signal output, said programmable control circuitry selectively connectable to said time indicating outputs for alternately providing initiating and terminating signals at said control signal output in accordance with times presented by said clock at said time indicating outputs corresponding to select connections when made between said time indicating outputs and said programmable control circuitry;
- and
- a solid-state A.C. power switching means having a control input, an A.C. power input and an A.C. power output, said control input connected to said control signal output of said programmable control circuitry, said switching means providing a conductive path for A.C. power from said A.C. power input to said A.C. power output in accordance with said initiating and terminating signals provided at said control signal output of said programmable control circuitry.
A timing circuit including:
- an A.C. powered D.C. voltage power supply;
- a crystal controlled time base generator connected to said A.C. powered and D.C. voltage power supply for providing time pulses at the frequency of one cycle per second;
- means responsive to A.C. power and operatively connected to said time base generator for providing a pulse for each cycle of A.C. power to said time base generator for synchronizing the operation of said generator including first and second NAND circuits, said first NAND circuit having one input connected to the output of said second NAND circuit and another input operatively connected for receiving an A.C. signal from said A.C. powered D.C. voltage power supply;
- said second NAND circuit having a first input connected to a D.C. voltage provided by said A.C. powered D.C. voltage power supply and having a second input;
- a coupling circuit operatively coupling the output of said first NAND circuit to said second input of said second NAND circuit, said coupling circuit transferring a logical 1 signal when provided at the output of said first NAND circuit to said second NAND circuit and maintaining said logical 1 signal at said second NAND circuit for about one-half the period of a cycle of said A.C. signal;
- and
- a stand-by battery operatively connected to said A.C. powered D.C. voltage power supply for providing D.C. power to said time base generator when A.C. power to said A.C. powered D.C. voltage power supply is interrupted.
Dependencies are inferred from the claim text.