Submitted by ThatFooFooLameShit t3_ynmm0u in DIY
Hattix t1_iv9z35l wrote
These guys work on a PIR sensor to detect motion and the solar voltage to tell when it's dark.
What you need to do a bypass on the PIR sensor, and that's really easy.
A PIR has three pins, a supply rail, a ground rail, and the sense line. They pull sense up when a moving subject passes the PIR by turning on a FET. Cut the sense line and solder a small resistor (e.g. 4.7 ohms) or just a bridge between the sense trace and the supply voltage.
Fair warning in advance: It will kill the battery.
ThatFooFooLameShit OP t1_iv9zgbl wrote
Thank you so much. Finally feel like I have the answer I was after.
No dramas on the battery - I fucked up by buying a security light instead of a normal one so atleast if I can get this working I wont feel like it was a complete wsste of money until I have to upgrade to a wired outdoor light.
Thanks again
Bok101 t1_iva99po wrote
4.7 ohm is not a small resistor! Sounds like you are describing a pull up, if we assume 5 volt supply voltage, and you ground the signal, you will be pulling a bit more than 1 Amp through the pull up resistor, or about 5 watt. A fitting size would be so where between 1k and 10k if intended for a pull up.
Hattix t1_ivacy5w wrote
You're replacing a fully turned on FET (which, you'll recall, has much less impedance than a few ohms!), you won't get that sort of current into the MCU's sense pin, it's a very high impedance.
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