User Manual BS 216 / Issue 1 © 1998 ASL Intercom, Utrecht, Holland.
6
9.0 PARTY LINE, TECHNICAL CONCEPT 11.0 TECHNICAL SPECIFICATIONS BS 216
ASL's BASIC Series offers a complete two way ('full
duplex') communications system. mains voltage range 100 - 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 /2.31 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. mic. impedance 200 ohms
Current drive is used for signal transfer. Each station presence filter +6 dB at 5 kHz
utilises a current amplifier to amplify the microphone signal frequency response 200 Hz - 13 kHz (-3 dB)
and place it on the common audio line where, due to the V electret mic + 9 V DC
constant line impedance (situated in the power supply
between XLR pin 3 and 1), a signal voltage is developed
which can be further amplified and sent to the max. load 200 ohms
headphones. max. output level 8 V rms (200 ohms)
This principle has three advantages:
- the use of a single audio line allows several stations to
talk and listen simultaneously. rejection 0 - 30 dB adjustable
- due to the high bridging impedance offered by each
station, the number of stations 'on line' has no
influence on the level of the communications signal. max. SPL 100 dBA
- power and audio to the intercom stations use the same
cable.
The Call signal is also sent as a current on the audio line. 4.6 Kohms (balanced mic level)
It develops a DC potential over the line impedance which Nominal input level -18 dBu to +6dBu (line level)
will be sensed by each station and interpreted as a Call -38 dBu to -14 dBu (mic level)
signal. max. input level +22 dBu (line level)
10.0 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.
POWER SUPPLY
MIC. PREAMP
gain 40 dB - 70 dB (adjustable internally)
HEADPHONES DRIVER AMP
max. output power 0.16 W rms (each can)
SIDETONE
BUZZER
AUX INPUT
Input impedance 30 Kohms (balanced line level)
+2 dBu (mic level)
Phantom power +30V DC (mic level selected)
DIMENSIONS AND WEIGHT
width 19" (483 mm)
height 1U (44.5 mm)
depth 124 mm
weight 1.85 Kg
GENERAL SYSTEM SPECIFICATIONS
intercom line impedance 350 ohms (1kHz)
2.2 Kohms (DC)
intercom line audio level nom. -18 dBu
max. +4 dBu
dynamic range 80 dB
call send signal 2.8 mA
call receive signal threshold +2.4 V DC
supply voltage +30 V DC (12 V to 32 V)
Note: 0 dBu = 775 mV into open circuit.
ASL reserves the right to alter specifications without further
notice.
(16 pages)
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