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Single Current Transformer for Dual Transistor Base Drive

IP.com Disclosure Number: IPCOM000050054D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Weekly, RD: AUTHOR

Abstract

This transformer construction efficiently provides base current for multiple switching transistors. Magnetically, the transformer includes two U-cores with I-caps, which effectively form two transformers. These are joined and share a common control winding. The fluxes in the outside legs may vary independently, allowing proportional drive in each transistor to act independently of the other transformer portion and transistor. The single control leg winding, however, can shunt or source base currents and emitter currents from or to both of the outside leg windings.

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Single Current Transformer for Dual Transistor Base Drive

This transformer construction efficiently provides base current for multiple switching transistors. Magnetically, the transformer includes two U-cores with I- caps, which effectively form two transformers. These are joined and share a common control winding. The fluxes in the outside legs may vary independently, allowing proportional drive in each transistor to act independently of the other transformer portion and transistor. The single control leg winding, however, can shunt or source base currents and emitter currents from or to both of the outside leg windings.

Fig. 2 shows a schematic diagram of the connection of the windings in a dual transistor switching circuit including transistors Q1 and Q2. The output of drive circuit 1 is applied to the control winding 2 of transformer 7. Secondaries 3 and 5 are connected between the bases and emitters of Q1 and Q2, respectively, while secondary windings 4 and 6 are connected in series between the emitters of Q1 and Q2, respectively, and the remaining circuitry to which the transistor emitters would ordinarily be connected.

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