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US 4,628,303 AGranted
Visual monitor for electrical signals
AssigneeSystem Development Corporation
InventorRichard C. Boyle
Life of this patent
Estimating the term…
Abstract
A circuit for monitoring the status of electrical signals, such as those present on the control and data lines of an RS-232 interface, includes a single operational amplifier and a dual-color LED indicator. The electrical characteristics of the LED's form a significant part of the circuit parameters. The monitor design provides a predetermined circuit input impedance and positive/negative switching thresholds to effect the selective illumination of the LED's.
Claims6
A circuit for monitoring the status of electrical signals comprising:
- a circuit input terminal for receiving said electrical signals, a voltage divider network coupled between said input terminal and a source of reference potential,
- an operational amplifier having a first and a second input terminal and an output terminal, means coupling said first input terminal of said amplifier to a predetermined point on said divider network,
- an LED indicator having a pair of terminals, means coupling the output terminal of said operational amplifier in common to said second input terminal of said amplifier and to one of said terminals of said LED indicator, the other of said terminals of said LED indicator being coupled to said source of reference potential.
Dependencies are inferred from the claim text.