Theatre Design & Technology - Winter 1979 - 33

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Techn ical Reports

An Automatic Cuing Device for Tape Transports
by Daniel H. Proctor

Advancements in electronic sound equipment are providing exciting opportunities in the use and manipulation of reinforced and
pre-recorded music and sound effects for the theatre. Naturally, contractors and consultants have responded by custom designing and installing theatre sound systems. However, tape decks, an essential
part of any system design, are themselves rarely custom designed to
meet the special requirements of the performance run. Needed, for instance, is a transport that accurately and automatically stops the tape
just before the next recorded cue reaches the playback head, thus
eliminating the need for manual cueing-up to spliced-in leader tape.
Since the auto-cueing function is not available in commercial machines, the alternative is a device that interfaces easily with existing
machines.
The following design is for such a device and works very well with
any tape deck having IC logic-controlled or relay/solenoid-controlled
stop circuitry that is electrically "higher" than its stop switch. The
stop switch, in other words, must operate by bringing to ground the IC
logic or relay/solenoid stop circuitry, thus completing a path directly
to ground for the stop circuit's load current, IL .

IC logic actuated control circuits respond up to 100,000 times faster, often using less than 1/100 the current, then relay/solenoid circuits. Therefore, the basic design should be altered for IC logic machines, substituting an NPN transistor for SCR, and eliminating the
manual "Reset" button and "Reset" indicator light as shown in the
schematic insert.
For tape transports featuring a remote control option, the connections to the stop button and to ground are most easily made at the
appropriate pins of the remote control socket. Otherwise, the machine
must be entered physically to make connections to ground and to the
"high" side of the stop button. These two connections to the machine
are the only ones necessary.
The heart of this design is the Light Reflection Emitter/Sensor Array (Fairchild FPA 104A or FPA 107 A) secured about 1/8" to 1 / 4"
away from the back (non-recording side) of the recording tape with
double-sided adhesive strip or other suitable mounting. The best
placement of the emitter/sensor is between tape guides in order that
the 1/8" to 1/ 4" space between it and the tape remains consistent.
A 3/16" diameter, sticky-backed white "dot" placed on the back

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Voltage Power Supply

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