First progress report on a multi-channel magnetic drum inner ...

6,3 Dynamic Tests with Minnesota J^^ininR Tape 2SL 10012L-29
VI-7
A procedure was next developed to study the performance of the
single wire head under dynamic recording conditions, i.e. with the
disc moving, using the best tape we have so far found, for this
purpose a pulser — to be described in Section 4.1 — was constructed.
?/h'en stimulated vdth a single pulse it produces a sequence of from 1
to 50 pulses, each of duration 0.2 microseconds, of amplitude to
15 amperes, and spaced from 10 microseconds on up apart. Two pieces
of tape were attached to the disc side by side and the double head
of Photograph 1-b mounted above them. A single pulse was recorded
statically on one of the tapes; when the disc was rotated this could
then be used as a trigger pulse to synchronize the pulser just
described.
To test the effect of superimposing one recorded pulse on another
of the same polarity the disc was set in motion and the pulser triggered
by the statically recorded pulse for three or four successive revolutions.
The voltage induced in the head by the dipoles thus recorded is shown
in Photographs 1-e and 1-t for 100 and 50 pulses to the inch respectively.
To test the effect of superimposing a recorded pulse on one of opposite
polarity the following procedure was adopted, A sequence of positive
pulses was first recorded. Then, by means of the statically recorded