Frequency/sensitive switching circuit
US4229681A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 29, 1978 |
| Grant date | Oct 21, 1980 |
| Priority date | — |
| Expiry date | Dec 29, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/392
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A switching circuit for energizing a load, such as fluorescent lamp ballasts, in response to a control signal of preselected frequency superimposed on AC power circuits which supply the load. A triac is gated to conduct the AC power to the load by a circuit including an impedance element and a series resonant LC network tuned to the frequency of the control signal. The gate circuit is arranged to block the control signal during all but a small portion of each half cycle of the applied AC power, thereby reducing the consumption of control signal power. Further, a current limiting resistor is connected between the series resonant network and the triac to extend circuit life by protecting the triac from excess current without adversely affecting the signal-blocking function of the gate circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.