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Overload Protection Circuit

IP.com Disclosure Number: IPCOM000096987D
Original Publication Date: 1962-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Jursik, J: AUTHOR

Abstract

The circuit provides overload protection for certain voltage sensitive devices which are damaged or caused to malfunction by excessive voltage swings at their inputs.

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Overload Protection Circuit

The circuit provides overload protection for certain voltage sensitive devices which are damaged or caused to malfunction by excessive voltage swings at their inputs.

This circuit utilizes a double anode Zener diode D1 in parallel with the input to the load. Diode D1 acts as an overvoltage switching device which breaks down when the input signal exceeds a desired maximum. Tunnel diodes D2 and D3 are connected in series with D1 and in parallel with each other. Upon conduction by D1, D2 and D3 switch through their negative resistance regions to develop a pulse in their output circuit. The output pulse from D2 and D3 is fed to a pulse transformer T1 through C1. T1 is used to actuate a relay control circuit. Contacts K1 in the latter open the input circuit to the system.

Diodes D4 and D5, in series with diodes D2 and D3, respectively, are to protect D2 and D3 from back voltage. The circuit thus provides protection against excessive voltages in either direction at its input. Upon receipt of an excessive voltage swing the input to the circuit opens until such voltage is removed. The circuit also has the advantage of having a low series resistance, a high shunt resistance, and low capacity coupling to ground while affording the overload protection.

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