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US 4,376,277 AGranted
Dynamic contact checking circuit
AssigneeHoneywell Inc.
InventorRobert A. Black, Jr.
Life of this patent
Estimating the term…
Abstract
A fail safe type of monitoring circuit for contacts is provided using an opto-isolator. The opto-isolator is energized in response to the operation of the contacts to clearly indicate whether the contacts are open or closed, and whether the circuit components are functioning in a valid manner.
Claims7
A dynamic contact checking means, including:
- opto-isolator means including light emitting diode means and light responsive transistor means which is capable of being electrically switched when said light emitting diode means conducts an electric current;
- bidirectional current conducing electric contact means adapted to controllably connect electric load means to a source of alternating current potential;
- first diode means connected in series with said light emitting diode means and said contact means to form first indicator circuit means;
- second diode means connected in series with said light emitting diode means to form second indicator circuit means;
- and said second indicator circuit means connected across said source of alternating current potential;
- said second circuit means conducting said current on every other half cycle of said alternating current potential, and said first circuit means conducting said current on the alternate half cycles of said alternating current potential when said contact means is closed.
3 more elements
Dependencies are inferred from the claim text.