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12/24 AC POWER
FREE TERMINAL
12/24 DC NEGATIVE
12/24 DC POWER +
DC TERMINALS MAY
ALSO BE USED AS
OUTPUT TO POWER
DC LOCK, IF AC
POWER IS SUPPLIED
3.3.2 DC LOCK WITH AC POWER
For convenience and economy, most DC electric locks can be operated from an AC transformer
when the DK-26 is used. Select a transformer of the same voltage as the lock (12 or 24). The
CPU board converts the input AC to DC to operate the lock. Make sure the capacity of the
transformer is large enough to operate both the DK-26 and the lock and that the transformer
is UL listed under the UL 294 standard. The lock must accept full wave rectified DC
power. This is true of most DC locks (including Securitron's Magnalocks) but some specialty
units require regulated DC power. You must operate those as described in the next Section.
Note finally that many DC lock installations call for battery backup. To achieve this, you must
employ a DC battery backup power supply and also follow the wiring description in Section
3.3.3.
DC locks come in "fail secure" and "fail safe" versions. A fail secure lock is secure when not
powered and a fail safe lock is secure when powered. All magnetic locks are fail safe. Figure
4 shows AC power being input to the AC terminals. The DC terminals furnish output power for
FIG. 3: OVERVIEW OF CPU BOARD
+
PRGM
HARD
SRC REX UCD HCD NCX
CODE
CODE
KEYPAD CABLE
SPDT
RELAY
CX
PROGRAM
RELAY
CONTACTS
Page 4
MICROPROCESSOR
DPDT RELAY
NOX NC2
C2
NO2 NC1
LOCK CONTROL
RELAY CONTACTS
RELAY CONTACTS
RATED AT 5 AMPS
AUX.
SOCKET
C1
NO1
PN# 500-16900
Rev. D, 12/11
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