Browse Prior Art Database

Self Clamping Driver Circuit

IP.com Disclosure Number: IPCOM000077549D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Barcomb, JG: AUTHOR

Abstract

In a driver circuit, a positive input to the base of transistor T3 turns it on and produces a voltage at the base of transistor T2, which is more negative than its emitter. This turns T2 on which applies base current to the base of transistor T1, turning T1 on and energizing the load device such as magnet winding 10.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Self Clamping Driver Circuit

In a driver circuit, a positive input to the base of transistor T3 turns it on and produces a voltage at the base of transistor T2, which is more negative than its emitter. This turns T2 on which applies base current to the base of transistor T1, turning T1 on and energizing the load device such as magnet winding 10.

When the input to T3 is changed to 0 volt or is made negative, T3 is turned off. This tries to remove the base drive to T2, which in turn removes drive to the load device transistor T1. When the "flyback" voltage from the inductive load device reaches +V, transistor T2 will begin to turn back on because its base is also at +V. The higher V tries to go, the more base drive T2 gets through resistor R3. This turns T2 and T1 on more. This continues until all the energy is removed from the load.

T1, T2 and R1 make up a quasi-Darlington circuit, but the addition of the other components, especially R3 to the drive voltage +V accomplishes the self- clamping feature.

1

Page 2 of 2

2

[This page contains 1 picture or other non-text object]