Wiring a Glass Break Detector

by Jeff Fisher

This application note covers a little background on glass break detection and then specific instructions for adapting the FGW-725 sonic glass break detector for use with the X-10 DS7000 Security System.

Background on Glass Break Detection

Glass break detection can be accomplished in a variety of ways. The oldest method is to bond metal foil strips to windows. These strips, when broken, open a circuit which is detected by an alarm console. These were difficult to install, and somewhat unsightly. More recent technologies detect the vibration or sound made by breaking glass. A very popular means of glass break detection is to attach a device called a "bug" to the glass being protected. This device directly senses the vibration caused by the impact required to break a glass pane. Two disadvantages exist with the "bug". False alarms are common as a result of vibrations from loud noises, like sonic booms, earthquakes, and similar disturbances. Where multiple panes of glass needed to be protected, a bug had to be attached to each pane.

More recently the technology has moved to detecting the acoustic sounds of breaking glass. This provides the advantage of one detector being able to cover a number of panes of glass. The simpler designs of acoustic detectors sense the high frequency tinkle of shattered glass. These simple designs tend to cause false alarms by confusing the breaking of glass such as tableware, or the sound of bells, with the sound of breaking windows.

Dual Technology Detectors Eliminate False Alarms

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Recently the glass break technology has been improved to eliminate false alarms from common occurrences. IntelliSense has developed a dual technology acoustic glass break detector. The IntelliSense unit listens for the very low frequency sound pressure wave created by the flexing of glass from a blow just before it breaks. This is called the flex wave. Once it detects a flex wave, it enables a high frequency detector to listen for the tinkle of glass breaking. Since both technologies need to detect the glass breaking, false alarms are virtually eliminated.

Using the IntelliSense FGW-725 Glass Break Detector with X-10 Security Systems

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The IntelliSense FGW-725 Dual Technology Glass Break Detector can be connected to an X-10 alarm system through a door window sensor. This is a battery powered detector designed to work with alarm transmitters. The design of the case provides a cavity to install the circuit board of the X-10 Door/Window sensor. A single 9 volt battery powers both the glass break detector and the door/window sensor circuitry. Having both sets of electronics powered by the same battery assures that the low battery supervision provided by the X-10 alarm system extends coverage to the operation of the IntelliSense Glass Break Detector.

Installing the X-10 Transmitter

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To use the IntelliSense FGW-725 Dual Technology Glass Break Detector with your X-10 alarm system, you just install the circuit board of the X10 DW534 Door/Window Sensor in the IntelliSense unit. To accomplish this, do the following:

  1. Prepare the FGW-725 Glass Break Detector Swing open the service door. Remove the screw near the LED ENABLE switch. Carefully pull the front and rear housings apart. You will find a "725 Kit" of screws, wires, and connectors in a plastic bag located inside the FGW-725 case. You will need these parts later. See Figures 1 and 2.
  2. Open the DW534 Door/Window Sensor Battery Compartment. Remove the battery cover from an X-10 DW534 Door/Window Sensor Unit. Take out the battery. Disconnect the reed switch (if attached) by loosening the two screw terminals.
  3. Open the case of the DW534. Remove the two screws on the back of the unit. With the back of the case off, you will see the circuit board.
    Caution: The DW534 Circuit Board is carefully tuned at the factory. You will notice some of the components are held in exact position with a wax material. Be very careful to not touch or move any of these components. High frequency tuning is accomplished at the factory with sophisticated test equipment by adjusting the position of several critical components.
  4. Remove the DW534 Circuit Board. Carefully lift the circuit board out of the DW534. Four moveable plastic pieces will remain in the front piece of the DW534 plastic shell: two buttons and two slide switches. These are not needed for the operation of the circuit board in the FGW-725 Glass Break Detector.
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    Install the DW534 Circuit Board in the FGW-725. Lay the DW534 circuit board in the cavity provided in the FGW-725 as shown in the Figure 3. It fits loosely, with the edge next to the battery compartment slightly cocked up.
  6. Connect the Battery Terminals.The battery terminal adapter in the "725 Kit" is wired with reverse polarity so it can adapt the connector on the DW534. Connect the supplied battery connector to FGW-725 circuit board as follows: Red wire connects to "+"; Black wire connects to "-". Snap the battery adapter onto the mating connector of the DW534. See Figure 3.
  7. Connect the Tamper Switch. Using the black wire (out of the "725 Kit"), connect the "NC" terminal to either of the "Tamper" terminals on the FGW-725 circuit board as shown in Figure 3.
  8. Connect the Sensor. Connect the brown wire (out of the "725 Kit") from the unused "Tamper" terminal on the FGW-725 to the terminal near the "NO" mark on the DW534 circuit board. See Figure 3.
  9. Replace the FGW-725 Cover. Carefully recheck all of your wiring. Then carefully snap the FGW-725 into place. There should be plenty of room in the case so that the DW534 circuit board does not get crushed.
  10. Insert the Battery. Install the battery in the battery compartment of the FGW-725 taking care to observe the polarity markings when orienting the battery.
  11. Electronically "Install" the Unit in your X-10 Alarm System. In order for your X-10 alarm system to respond to the glass break detector, you need to switch the alarm system console to "Install". Then open the door on the Glass Break Detector. The Tamper Switch will trip the alarm and cause a signal to be sent to the alarm console. The console should ding to indicate the unit is installed. If it does not, remove the battery for 5 minutes, reinsert, and try again. (This does the same as pressing the "code" button on a standard DW534.)
  12. Mount and Test the Unit. Follow the steps outlined in the FGW-725 Installation Instruction manual starting on Page 20.


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