“The Heathkit "The Informer ®" Ultrasonic Intrusion Alarm, Model GD-39,
is primarily intended to provide a warning when a specific area has been
penetrated by an intruder. This ability to detect movement within an area
can also be used as an automatic light switch for your garage, basement,
attic, or other place where you want entry into the area to turn on the
light. It can be used to sound a buzzer when movement occurs, such as a
child leaving its bed. The Intrusion Alarm is completely enclosed by metal
and can be installed anywhere that an electric outlet is available. It is
also provided with a case which simulates a book cover, which will help to
disguise the identity of the device. When the Intrusion Alarm has been
installed to survey an area, varying the ultrasonic waves by movement causes
a "lamp" socket to be switched on. Approximately 30 seconds later, an "alarm"
socket is switched on. The two sockets can be switched to automatically turn
off after 30 seconds, or to remain on until the Alarm is turned off. The devices
attached to the two sockets are furnished by the user, and may be of any description,
subject only to a total current limitation of three amperes AC from the two sockets.
The Intrusion Alarm is simple to build and install. Its solid-state circuitry should
provide many years of trouble-free, economical service. The two outlets permit you
to tailor the protection to the needs of your home or business.”