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Browse Prior Art Database

Magnetic Head Drivers

IP.com Disclosure Number: IPCOM000094554D
Original Publication Date: 1965-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Hahs, WR: AUTHOR

Abstract

The circuits provide write current to a magnetic tape write head. Each circuit uses a pair of transistors. These are actuated to control opposite directions of current through the write head in response to two data input voltage levels applied to terminal 11 in one figure, or in a complementary manner to terminals 11 and 12 in the other figure. Only two transistors are used in each circuit with the remaining elements being passive. The upper circuit is adapted for a single-ended head winding. The lower circuit is adapted for a split-head winding.

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Magnetic Head Drivers

The circuits provide write current to a magnetic tape write head. Each circuit uses a pair of transistors. These are actuated to control opposite directions of current through the write head in response to two data input voltage levels applied to terminal 11 in one figure, or in a complementary manner to terminals 11 and 12 in the other figure. Only two transistors are used in each circuit with the remaining elements being passive. The upper circuit is adapted for a single- ended head winding. The lower circuit is adapted for a split-head winding.

In each drawing, R1 and R2 provide a resistive voltage divider between a power supply V and one side of a diode D1. The intermediate point 10 in the divider is connected to the collector of a transistor. The transistors in the upper drawing are PNP and NPN and in the lower drawing both are NPN. Diodes D1 are connected between the ends of the respective voltage dividers R1 and R2 and one side of a respective head.

Diodes D1 are biased so that head current flows when one transistor is on while the other is off. Either binary voltage level of the data input causes one transistor to conduct while the other is nonconducting. Gate inputs connect to terminals 1 and 2 to control whether the circuit is enabled to operate a write head by disabling all current through the write head, such as when tape is being read.

Therefore, opposite directions of current are provided through the head in either circuit as a...