DIY Alarm Systems to Warn You and Scare Off Intruders

Although DIY Alarm Systems are not infallible (all of them are subject to giving false alarms), they help deter burglars and warn you of your neighbors in the event that someone does break into your home.

You can pay for a professionally installed burglar-alarm system, but you're paying mainly for labor.

If your handy, you can install your own, equally effective, system for anywhere from a few hundred dollars for a small apartment to around a thousand dollars for a rambling residence.


There are two basic choices in DIY alarm systems installations; perimeter system and motion-detector system. A perimeter system sounds an alarm when someone opens a door or window. A motion detector sounds an alarm when sensors inside the house detect motion.

The most effective system often combines two basic types: magnetic sensors on all the entry doors and motion-detecting sensors in all crucial spaces.

The Basic Equipment

Both types of diy alarm systems consist of sensors connected to a control box, a remote key switch to turn the system on and off, and a bell, siren, or other warning device. Instead of a key switch, you can install a digital key pad that allows you to periodically change the combination that unlocks the system. Whether you get a switch or keypad, be sure that it has delayed action to allow you to get through the door without sounding the alarm.

Both DIY alarm systems use 12-volt wiring and a transformer to convert 110-120-volt current to 12 volts. Some systems have rechargeable backup batteries to guard against blackouts. Perimeter sensors detect intrusion instantly, but they require a lot of wiring since every vulnerable entry must have a sensor. Wireless transmitters are now available for easier installation.

I find hardwired to me the most effective. I have hardwired in my home.Wired could be an esthetic or safety problem, unless you can hide the wires under moldings or snake them through the walls. Sensors that detect motion require less wiring, but they sound the alarm only when an intruder prowls in to a monitored indoor space.


Mount the control box of your DIY alarm system in a closet and rig the key switch or keypad near the entrance so that when you enter, you can quickly disarm the system. Install a panic button in the bedroom so that you can sound the alarm if you detect a prowler at night.

Mount the bell or siren both inside and outside the house. Intruders hate loud sounds inside the house. I have a strobe light on the outside so from the street people will see the light to know it is my alarm sounding.

Perimeter Systems

A simple perimeter system can bought in kit form, with a control box, a bell or siren, magnetic sensors, a remote key switch or keypad, and wiring. The kit can be expanded by adding panic buttons and more sensors. Magnetic sensors are made up of a magnet and a switch. Install the magnet on a closed door or window and the switch on the frame. If possible, recess them in the wood so that they cannot be seen from the outside.

Following the manufacturer's instructions, wire the sensor switch to the control box. When the door or window is closed, the magnet and switch will be close enough to each other to form an electric circuit. When the system is armed, if the window or door is opened, the magnetic field will be broken and the alarm will sound.

Each detector needs a shunt switch to disconnect it when you want to open the door or window without shutting off the entire system. To guard against window breaking, install vibration detectors on the glass panes.

Motion-Detector Systems

The sensors in a motion-detector system might be an electric eye, (with infrared or laser beam), ultrasonic (with inaudible sound waves), or passive infrared (body-heat sensitive). Install across a doorway of corridor and even outdoors, a few feet above the ground. Mount other sensors in the corners of rooms near the ceiling, aimed at crucial traffic areas.You can also install pressure-sensitive mats under rugs by doors and valuable items. When stepped on, these mats will sound the alarm.


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