Looking for cheap, simple PIR detector module

Richard Rasker · 2011-03-02T19:13:49+00:00

Hi all,I'm designing the electronics for a flatscreen TV lift system, for tuckingaway a flatscreen TV inside a low design-furniture cabinet (see for an example).As safety is an essential requirement for this type of machinery (the liftsystem is easily capable of squashing or even severing fingers), I'mlooking for a reliable PIR detector module. The idea is to have it "lookdown" from the back of the TV into the machinery, so that the system willstop immediately if a body part or (warm-blooded) household pet isdetected. The PIR detector should run off something between 6 and 12 volts(with a preference for 12V), consume no more than 10 mA, and provide amomentary low or high level signal upon triggering. A sensitivity settingis paramount.I tried several cheap PIR detectors which are used for automatic door bellsor proximity warning, but these have a tendency to trigger too readily;maybe they react to the changing heat pattern at the moment the lift startsmoving (the TV is warm after use, and the movement probably makes thedetector see quick changes in received heat), or maybe the PWM signal(though within permissible EMC levels) makes it go haywire.And oh, the cost may not exceed some 20 dollars for a complete module.Schematics for PIR detectors are also welcome, but no doubt, existingmass-produced modules are cheaper than anything I can make.And yes, I know that this will /not/ secure the whole thing against crushedfingers when the lid closes; we're contemplating several other measures forthis. Also, the remote control is IR, with mandatory "button-hold" action,so that the operator must always be in sight of the system, and nothinghappens automatically.Thanks in advance,Richard Rasker--

Mar 02, 2011 20 Replies

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George Herold 15 years ago

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why

eap

I like the idea of a counter balance or maybe a spring. You could also just move it very slowly.

George H.

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Looking for cheap, simple PIR detector module

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