Browse Prior Art Database

Bidirectional Coil Driver

IP.com Disclosure Number: IPCOM000094507D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Carroll, WC: AUTHOR

Abstract

This circuit energizes a coil L in either polarity. One end of L is connected to ground. The other end is connected to the junction of photosensitive resistor PC and the collector of transistor T. PC can be switched to its low resistance state by illumination from a lamp B. In its low resistance state, PC connects L between ground and a point of potential -V to produce a coil current I. While PC conducts, T is turned off by resistor R3 connecting its base terminal to be reverse biased with respect to the emitter.

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Bidirectional Coil Driver

This circuit energizes a coil L in either polarity. One end of L is connected to ground. The other end is connected to the junction of photosensitive resistor PC and the collector of transistor T. PC can be switched to its low resistance state by illumination from a lamp B. In its low resistance state, PC connects L between ground and a point of potential -V to produce a coil current I. While PC conducts, T is turned off by resistor R3 connecting its base terminal to be reverse biased with respect to the emitter.

Switch SW cooperates with resistor R2 to turn on B when SW is in the off position. In its on position, SW interrupts the circuit of B and connects T to turn on to conduct current I in the direction opposite to the arrow. Because PC is in its high resistance state while T conducts, L receives substantially all of the current of the circuit.

In another arrangement, T, R1 and R3 are replaced by a second photocell. This is connected to be illuminated by a second lamp when SW is in its on position.

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