ASL INTERCOM BS 181, User Manual

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User Manual BS 181 / Issue 1 © 1998 ASL Intercom, Utrecht, Holland.
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8.0 PARTY LINE, TECHNICAL CONCEPT 10.0 TECHNICAL SPECIFICATIONS BS 181
ASL's BASIC Series offers a complete two way ('full
duplex') communications system.
mains voltage range all units: 90 -240 V 50/60Hz AC
Users of the system are connected via a 'party line'. DC output voltage +30 V +/-5% DC
Master stations (with built-in power supply), beltpacks ripple and noise < 11 mV rms
and power supplies are interconnected via standard max. output current 1,8 A continuous / 2,3 A peak
microphone cable. One wire is used as an audio line,
one as a power line and the screen of the cable functions
as earth/return.
width 176 mm
Current drive is used for signal transfer. Each station depth 139 mm
utilises a current amplifier to amplify the microphone signal weight 0.9 Kg
and place it on the common audio line where, due to the
constant line impedance (situated in the power supply
between XLR pin 3 and 1), a signal voltage is developed
intercom line impedance 350 ohms (1kHz)
which can be further amplified and sent to the 2.2 Kohms (DC)
headphones. intercom line audio level nom. -18 dBu
This principle has three advantages: dynamic range 80 dB
- the use of a single audio line allows several stations to call send signal 2.8 mA
talk and listen simultaneously. call receive signal threshold +2.4 V DC
- due to the high bridging impedance offered by each supply voltage +30 V DC (12 V to 32 V)
station, the number of stations 'on line' has no
influence on the level of the communications signal.
Note: 0 dBu = 775 mV into open circuit.
- power and audio to the intercom stations use the same
cable.
ASL reserves the right to alter specifications without further
The Call signal is also sent as a current on the audio line.
It develops a DC potential over the line impedance which
will be sensed by each station and interpreted as a Call
signal.
9.0 GUARANTEE
This unit is warranted by ASL Intercom to the original end-
user purchaser against defects in workmanship and
materials in it's manufacture for a period of one year from
date of shipment to the end-user.
Faults arising from misuse, unauthorised modifications or
accidents are not covered by this warranty. If the unit is
faulty it should be sent in it's original packing, to the
supplier or your local ASL dealer, with shipping prepaid. A
note must be included stating the faults found and a copy
of the original suppliers invoice.
THIS PRODUCT WAS DESIGNED, DEVELOPED AND
MANUFACTURED BY:
ASL-intercom BV
MAARSSEN (UTRECHT) HOLLAND.
Tel. +31 30 241 1901, Fax +31 30 241 0638
POWER SUPPLY
DIMENSIONS AND WEIGHT
height 42 mm
GENERAL SYSTEM SPECIFICATIONS
max. +4 dBu
notice.