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Price: $7.99
These plans allow you to build a unit that can detect People From Over 300' Plus!! Animal Pests, Warm Spots, Heat Leaks. Sensitive enough to detect the "heat print" left by just touching an object! The body heat detector detects the presence of black body radiation down to 100 degrees Fahrenheit. All warm blooded organisms both human and animal are therefore easily detected. The device is similar to the infra red detector activated flood lights that have been around for some time. The difference is that this unit is very directional and can detect stationary objects as well as those moving. Range of human detection on a cool night is well over 200 meters. This long range application requires the unit to be mounted on a video tripod or the like . The unit when moved from areas of different temperatures must be allowed to stabilize for at least an hour before maximum sensitivity is possible. Farmers, ranchers or anyone plagued by destructive predators can use this device to alert them when a predator comes into range. The unit produces an audible tone and LED visual indicator, alerting the user so he may take terminating or other action against these pests. The unit is built into a rugged military gray plastic PVC housing of 3.5 od x 8” in length. A special diffraction lens focuses the thermal energy from the target to a sensitive pyroelectric temperature balanced detector. A sensitive amplifier increases the signal level to a value where it now triggers a window comparator. The threshold of triggering is set by an external sensitivity control that allows adjustment to the back ground conditions. The output of the comparator triggers a monostable timer that provides the pulse to light the LED visual indicator and the audio alert buzzer. The rear panel contains all controls and jack. The handle section contains the 8 aa batteries with a slip on removable cap. A 1/4-20 threaded hole in the main enclosure allows easy attachment to a vide tripod. A special output jack is available that provides the actual detected facsimile signal before the window comparator trigger. This can be fed to a scope, volt meter or other indicator for determining relative levels of signal strength. You will note that there are two modes of detection: The first utilizes the varying level of signal that is the result of a moving body, often the intruder or target subject. This mode will not detect a steady hot object such as a hot-plate etc.. This mode of detection requires a built in chopper wheel to fool the detector into thinking the infrared source in motion. The speed of the chopper shutter is externally controlled for optimizing certain targets. The maximum detectable sensitivity is around .1 to 10 chops per second with the lower speed being the most sensitive. An interesting experiment is to point the unit at a flat surface and allow it to stabilize. Now put your hand on the viewed surface and note the signal persisting for a time after your hand is removed. This will give you an idea of the system sensitivity being able to detect this very small differential temperature. Highly Directional 10-15 Deg Field of View 1-7/8"x 17" Cylindrical with Focus Tube Detects Bodies in Motion or Stationary Sources Via Chopper Battery Operated with Audio and Visual Alarms Sensitivity and Threshold Adjustments Easily Retrofits to Video Tripod for Long Range Detection BHT6 - Plans
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