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Browse Prior Art Database

One Millivolt Sense Circuit

IP.com Disclosure Number: IPCOM000080260D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Lewis, SC: AUTHOR

Abstract

The circuit shown in the figure is used to sense the rate of change of the voltage at the output of the common emitter, inductive transformer and regulator. Initially, a 10 milliamp current source CS is provided to charge up the large capacitors C1 and C2, to provide node A and the sense input line with appropriate voltage levels. 0nce the capacitors are charged, a one millivolt change at the input causes the collector node B of transistor T1 to rise to a positive voltage.

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One Millivolt Sense Circuit

The circuit shown in the figure is used to sense the rate of change of the voltage at the output of the common emitter, inductive transformer and regulator. Initially, a 10 milliamp current source CS is provided to charge up the large capacitors C1 and C2, to provide node A and the sense input line with appropriate voltage levels. 0nce the capacitors are charged, a one millivolt change at the input causes the collector node B of transistor T1 to rise to a positive voltage.

If the output line across the load is not rising sufficiently fast enough, transistor T1 is off and the Darlington pair consisting of transistors T2 and T3 are both on, causing the sense output to be low. This lowering of the sense output causes a positive voltage to be applied to the input across the inductor L1, to increase the current flowing through the inductor.

After a sufficient period of time, the current in the inductor L1 will increase till it is larger than the load circuit; i.e., the current through the resistor R1. When the input current exceeds the load current the difference between these currents, which is increasing, charges the decoupling capacitor C2 to cause a positive rate of change of the output voltage, which is also simultaneously increasing. When the voltage on the output node increases for a long enough period of time to cause point A to go positive, transistor T1 will turn on causing the Darlington pair to turn off, and the second Darlingto...