ID Tech Spectrum IIa - Manual (Page 8)

OPTIONAL FEATURES
“Gate” Operation
A spring-loaded gate protects the bezel opening from dust, dirt, and the insertion of foreign
objects, but easily opens to permit card insertion.
“Card Latch” Operation
The optional “latch” mechanism is available with Standard and Flush-Mount bezels. A TTL-
level control signal controls the mechanism’s operation. It holds an inserted card in place in the
reader’s slot until processing has been completed. Please refer to Appendix B for details of
“Latch Control” and “Card Latch” signals.
An optional feature available with the latch mechanism is “power failure latch release,” which
automatically unlatches the card when power fails. The host terminal’s +5V power supply must
not decay at a rate greater than 50V/s for this feature to perform reliably, because the power
for driving the latch motor in the event of a power failure is derived from the host terminal’s
power supply fi lter capacitor. (The latch circuit gets its power from the power supply’s decaying
voltage for a period of 20ms minimum to ensure a reliable latch release.) In the event the host
terminal’s power supply fi lter capacitor is too small for reliable unlatching, an external capacitor
with a voltage rating of at least 10V and a capacitance of 2200 microfarads must be used.
(The capacitor’s positive lead must be connected to Pin 1.) If required, a capacitor assembly (a
capacitor, with 6” wires and connetor) can be provided by the factory.
The “power failure latch release” feature operates by sensing the unit’s +5V supply input at (Pin
11). A circuit is used to monitor a 4.62V maximum threshold on the +5V supply and generates an
active, continuous low level if the +5V supply is below this threshold. A “reset pulse” occurs when
the +5V supply for the PCA rises above the threshold (4.62V). This reset pulse width ranges from
140ms to 560ms over the unit’s operating temperature range (-25C to +70C). During the delay of
140ms to 560ms, the LATCH CONTROL signal is not conducted to the motor driver circuitry.
“Card Present” Switch Operation
A “card present” switch is available as an option on readers that utilize the standard or metal
bezel designs. The switch provides a signal when the card is inserted into the front portion of the
reader, and it remains triggered until the card is withdrawn past the switch.
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