VS-900 Security Intercom Systems
Application Note
Connecting an External Amplifier to a VS-900RS
Sub-station Port
Summary
Connecting an external amplifier to a VS-900RS sub-station port provides that
amplifier with the audio distribution features of a VS-900 sub-station.
Details
As shown in the diagram below, the combination of resistors and capacitors block the
VS-900RS DC signaling and pad the signal to line level, suitable for connection to a
line-level input (transformer-isolated) of an amplifier such as the TOA 900 Series P-
912MK2 with a “B” Series input module (ex. B-01S). Note: This is for one-way
communication only - the PA amplifier/speakers will not act as a microphone for talk-
back (also see the VS-900AF card which offers a paging line output and 16 control ports).
Diagram
VS-900MF
VS-900RS
RS1 ~ RS4
A
B
C
Line 1 ~ 16
(CN1 ~ CN4)
10
µ
f 50V
1k
Ω
(
1/4 W)
+
+
10
µ
f 50V
1k
Ω
(
1/4 W)
330
Ω
(
1/4 W)
External Amplifier
with Input Transformer
(Zi >10k
Ω)
TOA Electronics, Inc.
601 Gateway Blvd., Ste. 300
So. San Francisco, CA 94080
1-650-588-2538 / 1-800-733-4750 V1,
All Rights Reserved, 2002
