Video-Based Motion Sensor | Video Circuits
The design is primarily based on an analog integrator circuit. The circuit integrates (i.e., sums) the input-voltage signal over a defined period of time. Based on an op-amp, the ideal circuit is shown in Figure 3. The factor –(1/RC) is constant, so the resulting output is inverted and proportional to the sum of the integrated values (i.e., proportional to the average of the signal in the integrated period of time). This is all it takes to “compress” the analog video signal. Although it seems complicated at first sight, it should be fairly simple by now (see Figure 4). The integrator is implemented by a National Semiconductor LM6134B, a fast, rail-to-rail, single-power supply op-amp (U3). The output should then be quickly converted to digital because the input changes very fast. Analog Devices’s AD9280 ADC (U1) with 32 Msps was selected so a 50-ns capture could be performed. The AD9280 was configured for 1 to 2 V of input to use the internal 2-V reference. A 1-V reference was obtained with U3:D. To prepare the input for this range, the signal was inverted with the op-amp U3:A and clamped just less than 1 V with U3:B (see Figure 2). Just before the integration, the video was inverted under 1 V. The integrator was designed to output a 1-V signal when a ground-referenced, fully saturated video signal was input in 4.3-µs intervals. Note that the integrator is offset at 1 V. So, after signal integration, the ADC will receive a signal that is from 1 to 2 V as required. The integration capacitor C12 is a low-leakage metalized polyester film type. R8 is a metal film resistor, also a 1% part. To reset the integrator, a 74HC4066 analog switch (U4) is used. It is controlled by the ATmega88 through the INT_ENABLE signal. The video output block performs the video highlighting. It is a transistor-based video amplifier that increases the gain when its enable signal is asserted low.
Motion Detector Op Amp - Bookshelf
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How to Make a Motion Detector - wikiHow
How to Make a Motion Detector. You're sleeping or your back is turned as a friend is trying to sneak up and scare you. Well not anymore!
MOTION DETECTOR KIT
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Pyro-Electric Sensor Hack
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MICROWAVE MOTION DETECTOR
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