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    Motion Detector Alarm Timer Modification

    Hi everyone,
    Can anyone guide me how to increase delay time of this sensor.
    I want to turn on signal for 15 mints after detecting motion.
    There are 2 ic's on this board
    1 LM339
    2 LM358
    Here are images.
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  2. #2
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    Re: Motion Detector Alarm Timer Modification

    Hi,

    I don't know about these things. I had a quick search and in my ignorance it looks like there is no timing device on your board (if there is no IC on the underside). It seems the op amp and comparator ICs are on most of these boards and are for signal detection and conversion from analog to digital signals, some just use op amps for analog outputs.

    These pdfs show how to add timing to a board without a timer:

    Page 13, PIR motion sensors Panasonic
    Page 28, Motion Sensors
    Page 5, MP Motion Sensor

    All three use and show the same circuit, the digital output timer, the PIR motion sensors Panasonic pdf also shows an analog output version.



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  3. #3
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    Re: Motion Detector Alarm Timer Modification

    Typically, the pyro detector produces a small signal that is amplified and filtered by one or more op-amp stages then fed to a comparator. There will be some delay mechanism in or after the comparator that sets the 'running time'. Unfortunately, without a schematic it will be almost impossible to determine which components are setting the delay although if they are found it is likely that it can be changed. Being surface mount construction might make it difficult to work on.

    You need to trace the schematic, as the pyro end will not be responsible for the timing, I would suggest starting at the 'output' end and work backwards. The black box on the lower left side is probably a solid state relay and it looks to be driven from U1 so that would be a good place to concentrate on.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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    Re: Motion Detector Alarm Timer Modification

    Its very hard to modify ready devices. Why didn't you built the whole device?

    A simple sugestion is to use only the last output(maybe comming from LM358). What does your device turn on? Is it a beeper, is it a light? If there are no put out pins for a load to be connected separately, then there certainly is something in the device.

    You catch the signal from the load avoiding any unnecessary modifications, delay it with 15min and put your own load after the custom delay circuit. Of course the original load will have to be disconnected.



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    Re: Motion Detector Alarm Timer Modification

    It's obviously a burglar alarm device, indicated by the tamper switch. 15 min delay sounds very unusual for burglar alarm, are you using it for a different application?



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    Re: Motion Detector Alarm Timer Modification

    Quote Originally Posted by FvM View Post
    It's obviously a burglar alarm device, indicated by the tamper switch. 15 min delay sounds very unusual for burglar alarm, are you using it for a different application?
    Normally the motion senor is connected to an alarm panel that will respond to the temporary activation of the relay and latch the alarm. It seems like the OP is looking to avoid the panel entirely and trigger something for longer than the motion activity. A delay relay might fit the bill here.



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  7. #7
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    Re: Motion Detector Alarm Timer Modification

    This is a very dangerous thing. Playing with alarms because you think 15 min is better than 15 sec means the criminal will get away until it activates. Second it makes the devices' integrity less and possibility for hacking by the criminal or not working properly high.



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