In the previous article I have explained how a PIR motion sensor works. There you can also find the schematic for the NV-1111.35 PIR sensor which is based on a popular three stage op-amp topology. Understanding this can help you understand other pyroelectric sensors as well.
This sensor is powered by a capacitive transformerless power supply with an output of 8V and 7mA of current.
The board includes a power 24V relay that can switch a load up to 1200W. The relay is controlled by the sensor's main board.
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| A rectifier diode and the output 8V Zener were burned which evaporated the copper traces. The board was repaired and components replaced |
Schematic of a capacitive transformerless power supply for NV-1111.35 PIR outdoor sensor switch
WARNING: this type of power supply is meant only for use cases where no humans or animals can touch the board. This is because it doesn't have a galvanic isolation. If the Zener diode fails or the wrong part is touched will lead to electrocution with mains voltage.
The schematic is self explanatory. To understand how a capacitive transformerless power supply works read this very interesting PDF which also talks about resistive power supply, half and full bridge types and which one can be used to drive SCRs and TRIACs:
It's possible to share schematic and PCB in DipTrace ?
ReplyDeleteThe link can be found in the previous article at the end of the page:
ReplyDeletehttps://www.programming-electronics-diy.xyz/2020/10/repair-of-outdoor-pir-d203s-thermal.html
Hope that helps.
Oh indeed, thank you very much.
ReplyDelete