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Core Driven Direct Coupled Transistor Drive Circuit

IP.com Disclosure Number: IPCOM000098438D
Original Publication Date: 1960-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Sommerfield, EH: AUTHOR

Abstract

When driving a transistor from the secondary or output winding of a core, the direct current resistance of the winding undesirably short-circuits the input to the transistor if the winding is directly connected to the input. A solution to this problem lies in the mating of germanium and silicon components, a germanium transistor and a silicon diode.

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Core Driven Direct Coupled Transistor Drive Circuit

When driving a transistor from the secondary or output winding of a core, the direct current resistance of the winding undesirably short-circuits the input to the transistor if the winding is directly connected to the input. A solution to this problem lies in the mating of germanium and silicon components, a germanium transistor and a silicon diode.

A silicon diode 15 is connected in series between a secondary or output winding 13 and the input to base 14 of an NPN type transistor 11. Diode 15 has minimum and maximum forward voltage drops of 0. 7 volt and 1.0 volt, respectively. The transistor has minimum and maximum forward base-emitter voltage drops of 0 volt and 0.5 volt, respectively.

If transistor 11 is conducting, current flows from -V through the base 14- emitter 16 path of transistor 11 and resistor 17 to V1. Since the drop across transistor 11 is a maximum of 0.5 volt and the minimum forward voltage drop across diode 15 is 0.7 volt, diode 15 is, in essence, reversely biased, and the winding 13 does not short out the base-emitter voltage. When a negative pulse occurs, diode 15 conducts and current is supplied to both resistor 17 and the transistor in a reverse direction and cuts off transistor 11.

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