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power supply and the interference introduced by the nearby equipments strictly. The creepage of low
quality TV can lead to the damage of other equipments.
2.5.3 Audio signal input
Audio port is BNC connection.
The input impedance is high so the tone arm must be active.
The audio signal line should be firm and away from the electro magnetic Interference and connected
credible which avoid false and joint welding and oxidation. The high voltage current should be avoided
especially.
2.5.4 Audio signal output
Commonly the output parameter of DVR audio signal is greater than 200mv 1KΩ(BNC) which can
connect the low impedance earphone and active sound box or other audio output equipments through
power amplifier. If the sound box and the tone arm can not be isolated, howling phenomena is often
existed. There are some methods to deal with the above phenomena.
1、 Adopt better directional tone arm.
2、 Adjust the sound box volume to be under the threshold that produces the howling phenomena.
3、 Use fitment materials that absorb the sound to reduce reflection of the sound.
4、 Adjust the layout of the sound box and the tone arm.
2.6 Alarm input and output connections
１、Alarm input
A. Alarm input is grounding alarm input.
B. Alarm input demand is the grounding voltage signal.
C. When the alarm is connected with two DVRs or connected with DVR and other equipments, it
should be isolated by relay.
２、Alarm output
Alarm output can not be connected with high-power load(no more than 1A).When forming the output
loop it must prevent the big current from relay damage. Use the contact isolator when there is a
high-power load
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