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    This is a chinese 3W LED bulb with PIR human sense trigger. Good design

    This came from a YouTube tear-down and well documented. His only error was measuring AC current with a DVM that internally uses P-P converted to RMS wit the internal assumption of a Sine wave ( common measurement error)

    He adds a tiny diode to the PIR to make it retriggerable by motion to extend time and prevent cycling.

    IF you compute the RC products, you can understand as I do how the energy is stored with 25T and low ripple using 15 ohms ESR per LED.
    I like this design, but would like a faster response time than is possible with a passive PIR.

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    Last edited by SunnySkyguy; 26th June 2016 at 19:06.
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    •   Alt26th June 2016, 18:41

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  2. #2
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    Re: This is a chinese 3W LED bulb with PIR human sense trigger. Good design

    The LED indicator output on the PIR board triggers the photo senstive triac in the LED board to enable the light from motion. Since LED does not emit any IR , but conducts a lot by heat transfer, the PIR detector window only senses human or animal heat emissions to enable the lamp built in one low cost unit. The power is impedance coupled by voltage direct off the ac line or "offline" by rectification from the triac to diode bridge with 18LEDs x3V current limited by 1uF plastic cap.
    A good design question lists your overall requirements™ The best question deserves a better answer. ™
    ... Tony Stewart EE since 1975

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