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Entry-Master Option-4 Hardware Installation Guide
The second method employs the use of an external power supply, and acts very much
like a relay output, except that in this case, only the negative power lead can be
interrupted via the collector (C) output and the ground (Gnd) connector (see Figure 2
below). In this case, when the transistor output is active, the collector output "drops" to
ground, thus allowing the current from the external power source to flow into the locking
mechanism.
Please note that in both cases, a reverse-bias diode is employed across the coil,
in order to prevent negative back-feed on the circuit. A diode of type 1N4001 is
recommended.
The installation of diodes is necessary and extremely important!!!
Failure to follow these instructions may damage the Option-4 board!!!
The third method involves the use of an isolation relay, powered directly by the
transistor. The advantages of this method are: (1) the use of AC locking mechanisms
(the first two methods can operate only with DC power); (2) the voltage and current
limitations are dictated by the isolation relay, not the transistor; (3) either the positive or
negative leg of the lock power may be interrupted by the relay (when using a transistor
output, only the negative leg may be interrupted); and (4) it is a little more straight-
forward for those who are accustomed to using relays.
In this method, an external power supply is used, but the transistor actually powers the
isolation relay (see Figure 3 below). Please note that a reverse-bias diode is installed
across both the relay coil and the locking mechanism coil.
