Browse Prior Art Database

Dual Magnetic Head Amplifier

IP.com Disclosure Number: IPCOM000095906D
Original Publication Date: 1964-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Schaaf, RL: AUTHOR [+2]

Abstract

This circuit produces two separate, sequential, nonoverlapping pulse trains from a single magnetic read head. Since the pulses do not overlap, a sequence of three pulses can be obtained with a minimum amount of additional circuitry.

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Dual Magnetic Head Amplifier

This circuit produces two separate, sequential, nonoverlapping pulse trains from a single magnetic read head. Since the pulses do not overlap, a sequence of three pulses can be obtained with a minimum amount of additional circuitry.

Stationary magnetic read head 1 is energized by rotating emitter wheel 2 having a single tooth. As the tooth passes magnet 3 of head 1, a voltage of one polarity is induced in head 1 by the leading edge of the tooth and a voltage of the opposite polarity in induced by the trailing edge of the tooth.

A pair of diodes 4 and 5 is normally forwardly biased by circuits including resistors R3 and R4 to maintain transistors T2 and T1 cutoff.

When the voltage induced in head 1 is of such a polarity that the junction A is negative with respect to the junction B, e. g., by the leading edge of the tooth, diode 5 is reversely biased permitting forward biasing of the base emitter junction of transistor T1. T1 conducts in saturation to produce an output pulse at C and then returns to its nonconductive state when the pulse in head 1 terminates.

Shortly after, the trailing edge of the tooth induces a voltage of the opposite polarity in head 1 to cause B to go negative with respect to A, thus turning on T2. T2 produces an output pulse at D and returns to its cutoff state. The spacing between the pulses depends upon the width of the tooth on wheel 2.

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