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Simple LED Alarm Bell for CCTV recorder

I'm looking to get this DVR for a new CCTV installation. Shown here:

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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

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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?

Reply to
me
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It was simple until you said you wanted the LED to flash. Are you good with a solder gun? It is easily done, but it's going to be a little intricate if you're only a DIY'er. Do you want the buzzer to be intermittent with the LED, or a small steady buzz? The switches are easy because you can use a DPDT switch to "shunt" the alarm device.

Reply to
Jackcsg

I think a small steady buzz. Note that the CCTV DVR box has 8 wires all 500ma, 12volts each. All 8 wires from CCTV DVR would go into one black box that is drilled on the front, 8 LEDs, 8 switches (1 per sensor), and buzzer inside.

There should be some way to handle the amp and voltage so it doesn't go back and blow up the CCTV box.

I've forgotten everything they taught me in science classes. If I had a diagram I could show it to the people in Maplin.

Reply to
me

The thing to keep in mind is that it is possible to have multiple alarms at once. I'd be keeping it simple, and with the least amount of draw as possible. The simplest way would be to come off the positive side of each LED, with a diode gowing to the buzzer, (piezo) positive, and the other side going to ground. This will prevent any voltage feedback to the DVR from the current draw. I'd keep the LED steady, along with the sound. If your dead set on "flashing" an LED(s), I'd be using an external power supply and isolating the voltages so you don't damage the DVR. Stay away from any electro-mechanical piezo's, as they draw more power. The ceramic's draw between 3 ma to 8 ma. You have more than enough power. Keep it simple. K.I.S.S. I would imagine all the grounds on the DVR outputs are common, unless the unit switches to ground. Remember, and LED is a diode.... If you need a drawing, I'm sure I could put one together for you.

Reply to
Jackcsg

You can buy them with the resistors embedded, at 5 to 28vdc, some even to 60 vdc. (I'm looking through my Newark Catalog), they draw 17 ma at 12 vdc. I know the Shack carries them...lord knows I've bought a few hundred there....(I love it when they ask me "what's it for?")

I "think" from 12v to 3v is a 660 ohm resistor...to give you voltage drop...something like that.

Reply to
Jackcsg

You'll have to knock the voltage down for the LEDs too..otherwise they = make a nice crackly-popping sound as the plastic shoots across the room.

I "think" from 12v to 3v is a 660 ohm resistor...to give you voltage = drop...something like that.=20

Reply to
Crash Gordon

I need some really small one's without shoulders (maybe 1/8" dia. or = less...preferably 12v to keep it simple. I'm prototyping an idear for = alarm system. They got anything in Newark cat.? I also need about 10 = feet of fiberoptic...any scrap junk is fine it's not for = communications...if anyone's got a piece? I don't want to buy a whole = roll in case my project is a bad idea.

Reply to
Crash Gordon

What kind of mount do you need? They have panel mount indicators with 6" leads, they are around $2.38 a piece. They draw 2 ma. There are cheaper ones too. You can buy just a patch cord for your fiber project already connectored for fairly cheap.

Reply to
Jackcsg

I think the CCTV DVR would control the flash. I expect the alarm to only go off when someone walks past or stands under it. It might only sound for a second or so. I'm thinking of hooking up a PIR sensor to it. I don't need to worry about the flashing as the CCTV DVR is going to control the on/off side of things.

Reply to
me

I don't want any mount, no shoulder flange, nutthin special...at least = for my mock up. It has to fit in very small space, so I'm just gonna hot = glue them into small opening for the prototype.

Patch cord's too expensive considering that I'm only after the bare = fibers inside the jacket.

Does your parts supplier have a website with the leds listed?...most = online's don't have the little stuff online.

Reply to
Crash Gordon

Yes. Go to

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they have everything, and good sales support for the gidget gadget world. Your not trying to make one of them there chea pet lighted heads are you..... I did have a reel of 8 pair single mode fiber, but the reel wouldn't fit in my rental car, so I left it in Wyoming on the jobsite.

Patch cord's too expensive considering that I'm only after the bare fibers inside the jacket.

Does your parts supplier have a website with the leds listed?...most online's don't have the little stuff online.

Reply to
Jackcsg

LOL... no its two separate projects..the led thing is for an alarm = idea..the fiber is for my daughter's science project (one reason I don't = wanna spend $$ on it...they get thrown away 10 seconds after their = presentation is finished).

Wyoming...beautifull..but way too freekin cold.

Thanks for the link to Newark.

Reply to
Crash Gordon

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