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False alarm of PIR sensor

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Nov 9, 2022
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Hi All!

Currently I'm working on device that will be used in home automation systems. Device is designed to detect movement and set some values let's say brightness of a lamp, microcontroller is on board too. Device is supplied from 18V source.

First, big problem that I met is connected with PIR sensor. Hausing of my device is quit small and could be a part of a lamp/or something so it's quit difficult to say what can be the maximum temperature inside this hausing, maybe 50 C, 60 C. PIR sensor is part of hardware so only lens is outside the hausing. Finally I have a problem with false movement detection when device is close to let's say window, door or any others air movement sources... I noticed that the differences between themperature inside and outside the hausing are a reason of this problem.

Do You have maybe some experience with that kind of application/PIR's sensors? Maybe You can recommend some PIR that is not sensitive to external temperature and general environment conditions.

Thank you in advance for your help, that's my first post here so I'm glad to be in that technical society :)


I guess you need to be more clear with your descriptions.
(Indeed I guess I never have seen a more vague description at all)

Just the first two lines:
* "I´m working" --> repair, design, hardware, software, mechanics...?
* device --> ???
* in home automation system --> as server, sensor, actor, or multiple of them? Is it relevant for the problem at all?
* detect movement --> mechanical movement? What (fluid, gas, solid, .. what size, what speed) with respect to what?
* set some values --> ??? Is it relevant?
* microcontroller is on board -->What microcontroller, what interface, which board? Is it relevant?
* 18V source --> AC, DC, ... Is it relevant?

So please focus on the problem. Omit everything that is not relevant to the problem.
Give informations like the PIR manufacturer and part number, the used schematic, interface, PIR supply voltage, fotos (100kBytes should be sufficient)...

Give a brief but focussed description about your test method, the expectation and the unexpected behaviour. Voltages, timing, scope pictures...


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