Simple LED Alarm Bell for CCTV recorder

[Rich Grise]

On Mon, 14 Mar 2005 21:23:30 +0000, me wrote:

I'm looking to get this DVR for a new CCTV installation.
Shown here: http://www.securexsolution.com/download/se104s-um-e.pdf

Basically, when someone walks past the sensor, it should trigger the
alarm I wire up to the back of the CCTV DVR. I think most time lapse
VHS recorders have sensor/alarms terminals on the back.

On page 9 and page 10 of the above .pdf, there is a picture of the
sensor (Dry Contact Input), a picture of a LED relay, and a picture of
an alarm bell relay.

Can someone tell me an easy way to hook this up so when someone
triggers the sensor, I can get a quiet buzzer to sound and and a LED
to flash. I want an on/off switch for each sensor, only want to buy
one buzzer and 8 LEDs.

I'm in the UK and www.maplin.co.uk has parts online for everything
like this. I suspect I have to make my own kit as I can't find
anything pre-built in google for CCTV alarm bells.

The system I'm getting has 8 sensors input and 8 alarm bell 500ma, 12v
outputs. The picture only shows 4 and 4. Should be quite simple
though. Any ideas?

Should be as simple as eight resistors for the LEDs and eight diodes for
the bell. How to connect them depends on if the 12V is high-side switched
or low-side switched. If it's high-side, i.e., one output is "ground" and
the other is either 0V or +12V, then use 8X 1K resistors, one from each
output to the anode of a LED, and ground the LED cathodes. Use 8X 1N400x
diodes, with the anodes each to one output (along with its LED resistor),
and all of the cathodes connected to the relay coil, and the other side of
the relay coil grounded.

If they're low-side switched, i.e., there's a constant 12V, and the
outputs go from floating (or maybe a 12V pullup) to a switch to ground
(e.g., a transistor collector), then connect all 8 LED resistors (on the
anode side) to the +12v, and each LED cathode to one of the outputs, and
the 8 diodes' cathodes to the outputs, their anodes together to the relay
coil, and the other side of the relay coil to +12.

Good Luck!
Rich

 

I'm looking to get this DVR for a new CCTV installation.
Shown here: http://www.securexsolution.com/download/se104s-um-e.pdf

Basically, when someone walks past the sensor, it should trigger the
alarm I wire up to the back of the CCTV DVR. I think most time lapse
VHS recorders have sensor/alarms terminals on the back.

On page 9 and page 10 of the above .pdf, there is a picture of the
sensor (Dry Contact Input), a picture of a LED relay, and a picture of
an alarm bell relay.

Can someone tell me an easy way to hook this up so when someone
triggers the sensor, I can get a quiet buzzer to sound and and a LED
to flash. I want an on/off switch for each sensor, only want to buy
one buzzer and 8 LEDs.

I'm in the UK and www.maplin.co.uk has parts online for everything
like this. I suspect I have to make my own kit as I can't find
anything pre-built in google for CCTV alarm bells.

The system I'm getting has 8 sensors input and 8 alarm bell 500ma, 12v
outputs. The picture only shows 4 and 4. Should be quite simple
though. Any ideas?