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Multiple Gap Head Circuits

IP.com Disclosure Number: IPCOM000093098D
Original Publication Date: 1967-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Smith, R: AUTHOR [+3]

Abstract

The circuits provide selection of either of two multiple gap heads, crosstalk compensation, and improved data bit detection.

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Multiple Gap Head Circuits

The circuits provide selection of either of two multiple gap heads, crosstalk compensation, and improved data bit detection.

Characters are represented by a nine-bit code configuration recorded on a media such as a magnetic tape. The circuit in A shows only three-bit channels for either of two nine-gap heads, designated right and left. The right head includes read coils 1...3. The left head includes read coils 4...6. One head is selected by applying + 12.0 volts to its related terminal 7 or 8 while grounding the other terminal.

The coils of the selected head feed emitter-follower circuits 9...11. The latter present high-impedance inputs for improving the signal-to-crosstalk ratio by a factor of two. Circuits 9...11 provide outputs on lines 12...14 to crosstalk compensation networks 15 that include 100K ohm and 5.1K ohm resistors. Coils
1...3 and 4...6 are oppositely wound. The compensation networks feed amplifier- detector circuits 16...18.

Assume a signal in track 1 generates crosstalk in track 2. The crosstalk in track 1 is 180 degrees out-of-phase with the signal in track 2. The signal in track 2 generates current into the amplifier for track 1. The crosstalk generates current out of the amplifier for track 1. With the component values indicated, no net or minimum current should flow in track 1. Crosstalk in track 3 is cancelled similarly. Drawing B shows conditions with signals in tracks 1 and 3. Crosstalk from more than just adjace...