Studio Technologies 45DC - Manual (Page 11)

Model 45DC User Guide Issue 1, January 2015
Studio Technologies, Inc. Page 11
the back panel of the Model 45DC. This
allows connection by way of a cable-
mounted etherCON plug or a standard
RJ45 plug. The Model 45DC’s Ethernet
interface supports auto MDI/MDI-X so
that most cabling implementations will
be correctly supported.
External 12 Volt DC Input
An external source of 12 volts DC can be
connected to the Model 45DC by way of a
4-pin male XLR connector which is located
on the back panel. While the requirement
for the external source is to be nominally
12 volts, correct operation will take place
over a 10 to 18 volt range. The Model 45DC
requires 1.0 amperes maximum for cor-
rect operation. The DC source should be
terminated to a 4-pin female XLR connector
with pin 1 negative (–) and pin 4 positive
(+). Purchased as an option, the PS-DC-02
power supply is available from Studio Tech-
nologies. Its AC mains input allows connec-
tion to 100-240 volts, 50/60 Hz and its 12
volt DC, 1.5 amperes maximum output is
terminated on a 4-pin female connector.
As previously discussed in this guide, an
Ethernet connection that provides Power-
over-Ethernet (PoE) can serve as the Model
45DC’s power source. Alternately, an exter-
nal 12 volt DC source can be connected.
For redundancy, both PoE and the external
12 volt DC source can be connected at
the same time. If both PoE and an external
12 volt DC source are connected, power
will be drawn only from the PoE supply. If
the PoE source becomes inoperative the
12 volt DC source will provide the Model
45DC’s power with no interruption in opera-
tion. (Of course, if both PoE and Ethernet
data support are lost that is a very different
situation!)
Party-Line Intercom
Connections
The Model 45DC’s party-line intercom
interface is designed to function in two
distinct ways. It can be connected to one
or two “powered” broadcast-standard
2-channel party-line intercom circuits or
directly to one or two sets of party-line
intercom user devices. A single-channel
party-line intercom circuit, such as fre-
quently associated with equipment from
Clear-Com, has DC power and one audio
channel on a 3-pin XLR connector. The
connector is wired such that common is
on pin 1, 22 to 30 volts DC is on pin 2,
and audio is on pin 3. An impedance-
generating network provides a 200 ohm
audio load from pin 3 to pin 1. When the
Model 45DC’s party-line interfaces are
connected to existing intercom circuits
they act, from an audio standpoint, as
standard user devices. They don’t draw
(nor supply) any DC power.
The Model 45DC’s two party-line inter-
faces can serve to create two “mini” in-
tercom circuits. They each provide a 28
volt DC intercom power source and a 200
ohm impedance generator, allowing a
limited number of single-channel intercom
user devices to be directly connected.
The Model 45DC’s two internal 28 volt DC
power sources each have a maximum
current of 150 mA. This modest amount
of power can be very useful but requires
that the type and number of connected
user devices be selected appropriately.
Many entertainment applications use
the legacy Clear-Com RS-501 beltpack
and each Model 45DC intercom circuit
can directly support up to three of them.
With the newer and more energy efficient
Clear-Com RS-701 it should be possible