Construction and testing
A single-side PCB for the PIR sensor based power saver is shown in Fig. 3 and its component layout in Fig. 4. Enclose the PCB in a small box in such a way that you can easily connect 230V AC input to CON1 and the light/fan to CON3 at rear end of the box. Connect the PIR using a 3-wire cable to the PCB at CON2 and install it at a suitable location in your room.
Before using the PIR in the circuit, manually check it by connecting Vcc and GND pins of PIR to a 9V (or 12V) battery. Then check for change in voltage at signal output pin with respect to ground by waving your hand in front of the sensor. Adjust sensitivity and time controls of the PIR as per requirement (else turn both presets clock-wise to have highest sensitivity and high time signal). The dome surface of the PIR should be clean for better sensing.
Download PCB and component layout PDFs: click here
After manually checking the PIR, remove the battery and connect the PIR to the PCB. You can assemble the circuit on the PCB with terminal connectors for CON1 (input) and CON3 (output).
Verify that voltages at the test points are as per the table before using the circuit. Check to see if LED2 is off and relay is energised. After some time, LED2 will glow and the relay will get de-energised. Your circuit is now ready!
Some PIR sensors require an initial stabilisation time of 10 to 60 seconds in order to function properly. During this time, any motion in its field-of-view (near 15m range) should be avoided.
Main DC voltage at TPI is unregulated.
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