CCTV camera air horn upgrade

Thread Starter

Juslsn

Joined Dec 19, 2020
3
I have a Lorex security camera system.
The cameras have a light built into them which can be triggered from the Lorex app.
I want to trigger a 12v air horn instead of the light.
I bypassed the light circuit board, When the light is activated, I have 5 volts. The relays I have need 12v trigger. Need help moving forward.
 

MisterBill2

Joined Jan 23, 2018
7,728
The arrangement that will drive the 12 volt relays from the 5 volt signal will depend on how much current the relays draw to operate. Certainlt 5 volts is enough to switch on an NPN transistor with the 12 volt relay as the collector load. So the only hard part will be discovering the value of the resistor needed to limit the base current to the proper level. And that can be done experimentally. The question is if the switched 5 volts can deliver enough current to switch the transistor on completely.
 

Thread Starter

Juslsn

Joined Dec 19, 2020
3
The arrangement that will drive the 12 volt relays from the 5 volt signal will depend on how much current the relays draw to operate. Certainlt 5 volts is enough to switch on an NPN transistor with the 12 volt relay as the collector load. So the only hard part will be discovering the value of the resistor needed to limit the base current to the proper level. And that can be done experimentally. The question is if the switched 5 volts can deliver enough current to switch the transistor on completely.
How would I measure output current?
 

MisterBill2

Joined Jan 23, 2018
7,728
If you have already made the separation between the control and the camera, it will be simpler to measure the current needed at the camera input to provide the five volts. If you have a meter that can read current just connect it between the 5 volts input to the camera and the 5 volts out from the control, with the commons connected between the two as they had been. Then power them up as it had been and used the remote control to switch on the camera, That will give you the original designed current, which should be the simple value to use.

Another option is to measure the coil current drawn by the relay you want to use to control the horn power. That will determine the driver transistor that you will need.
 

Tonyr1084

Joined Sep 24, 2015
5,549
I have a Lorex security system. The darn thing stinks! HAD a DV908 model that started having playback issues. They warranty replaced the unit with another 908. Had different issues but still within the playback mode. Then they replaced that with a D841. Playback is superior. However, it often fails to detect motion - and I'm talking about a car passing the camera at approximately 25 MPH. I've given up trying to get them to provide something that actually works.

MY Lorex has an ALARM output. If ANY camera detects motion and that camera is set for "Alarm" then the output will go high and trigger an audible alarm. And yes, it's 12 volts. Where you're getting 5V from - I don't fully understand. The DVR and Cameras all operate on 12VDC.

Off hand I don't know how much current the Alarm is capable of, I haven't read up on that part of it. Nor do I care to have the alarm trigger every time a snow flake floats past the camera (assuming it's detecting correctly) (oh, and yes, I've reset to factory default MANY times). Summer time I have bugs triggering some of the cameras. At night some of those bugs see the IR LED's on the camera and are attracted to it. They will buzz around the camera for several minutes, triggering a recording event. Also triggering my cameras is steam from the furnace and clothes dryer. An air horn would be extremely annoying.

Are you attempting to frighten away animals? If you have neighbors they're going to get tired of the air horn. AND on top of the "Air Horn" you're going to need a source of compressed air. If you're running a compressor to blow the horn - that's a lot of electronics to just make a loud noise. Since it's 12V, a car horn might suit your desired outcome. Personally I think it's not a good idea to be blowing horns at all hours of the night.
 

MisterBill2

Joined Jan 23, 2018
7,728
OK, it seems that I was thinking of something else with my last post. It was a motion sensor, not a wifi remote trigger. Still, the advice with the 5 volts holds. And it might be a motion sensor in a garage, or protecting the garage door area. I have those, along with a few "nightfighter" LED lights. Really bright light does tend to discourage most bad guys. The barking dogs convince them to leave.
For the TS, it might be a 12 volt powered air horn, or one run from an air tank. I made one of those many years ago, string tripped, no electronics at all. An empty 25 pound propane tank with a different valve and filled with compressed air at 125PSI. The trip was a string that released a crimp in the plastic air hose. Once triggered it was very loud for two minutes and then just loud for a few more minutes. Inside the garage there were no false triggers, only bad guys running away in the dark.
 

Thread Starter

Juslsn

Joined Dec 19, 2020
3
The system can be set so the light on each camera only comes on for 10 seconds when triggered from the app. I extended the light output wire, when activated I have 5 volts. My clients business is located a less than desirable area and has had people crapping in front of his front door. Gross I know. I was hoping it could trigger horn while viewing the camera. But my 5v is not a strong enough input for the Drok 300001 Micro Led DcDc Digital Boost Voltage Converter Adjustable Volt Regulator Board Module Power Supply Transformer.
Im not sure how to up the current. Think I need about 2-3amps. And the 3 hours I’ve spent watching Crash Course hasn’t helped me.
My plan B is to use wifi contact closure. But will have to switch to a different app.
Any options on how to increase the amperage coming out of the camera light output wire??
 

MisterBill2

Joined Jan 23, 2018
7,728
It is not likely that more power would be available from the camera system, but the 5 volts should be enough to operate a solid-state relay that can switch 10 to 15 amps. CRYDOM is the brand that I first used, but now there are quite a few other brands available. Then a second power source will be needed, but it will not need to be switched by other means. And those solid state relays have well labeled screw terminals to connect to, in addition to providing very good isolation. Si that would be one way to control the air horn.
 
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