Questions About Circuitry of Zones in Home Security Control Panels

[Saeedk9574]

Hi everyone,

I have a couple of questions regarding home security control panels and PCB design that I hope someone can help me with.

First, I'm curious about the circuit and components used in the zones of a home security control panel, particularly how sensors connect to the microcontroller. What are the typical components involved, and how do they interact to ensure reliable performance in detecting security breaches?

Additionally, I’ve noticed that some PCBs utilize corrugated tracks instead of traditional straight traces. What is the purpose of using these corrugated tracks? Are there specific advantages they offer in terms of signal integrity or manufacturing?

Thanks in advance for your insights!

 

[BradtheRad]

We moved into a home which previously had a security system installed. Each door and window had a sensor on its frame, total 15 or 20. Exposed wiring ran to every sensor. I believe all sensors were wired in series.

The circuit board was in a closet. A siren faced out of the attic vent. I tested it once by closing every window and arming the panel. As soon as I opened a window the siren turned on loud enough to annoy neighbors in the area. Only the front door had a delay which required using a second key within 30 seconds, in order to silence the alarm.

We kept the system disarmed because we realized we ourselves would carelessly cause the siren to turn on without intending to.

 

[Saeedk9574]

We moved into a home which previously had a security system installed. Each door and window had a sensor on its frame, total 15 or 20. Exposed wiring ran to every sensor. I believe all sensors were wired in series.

The circuit board was in a closet. A siren faced out of the attic vent. I tested it once by closing every window and arming the panel. As soon as I opened a window the siren turned on loud enough to annoy neighbors in the area. Only the front door had a delay which required using a second key within 30 seconds, in order to silence the alarm.

We kept the system disarmed because we realized we ourselves would carelessly cause the siren to turn on without intending to.

I want to make one of them. These are the pics I have gotten on the Internet. Accordingly, I got these two questions.

 

[BradtheRad]

I didn't examine the sensors but I'm pretty sure one part was magnetic and the other part was a reed switch. The magnet holds the switch closed (conducting) while the window is shut. The circuit is a loop of closed switches connected around the entire house. Probably a few volts and a few mA.

Someone opening any door or window moves a magnet away, causing a reed switch to open. This breaks the circuit. The central board detects this and activates the alarm.