The Complete project is about The motion activated sensor circuit and its working. But here is one interesting fact: the entire circuit including the PIR Motion sensor is working in Direct AC voltage.
Here we are not using 12V DC power supply or any other DC power source to work the circuit. This Transformerless Power Supply can be easy for building this Human Detection Based Bedroom Light ON/OFF Circuit. The complete details of this project is provided here.
NOTE: The circuit diagram, PCB Layout also you can download and use for personal use only.
AC powered human detection based light on/off circuit
Components required
- PIR Motion sensor
- 8050 transistor.
- 12v zener diode
- 1N4007 diode
- BT136 Triac
- 1K 1Watt resistor
- 1000uf/25v capacitor
- 474/400v Capacitor
- 2.7K resistor, 330 ohms resistor
Working
When the AC supply is on The light starts to turn on and after some time light is turned off. Then the second time the light only turns on if any human body detection is within the range of detection.
The entire circuit is working from a Direct AC. There is no external power source connected to the circuit to get a DC supply for Sensor and 5V DC relay. The transformerless power supply provides the DC voltage to work the circuit.
The 474/400V capacitor and 1K 1-watt resistor are connected to direct AC voltage and it passes the low current AC voltage and it will be rectified by the 1N4007 full bridge rectifier circuit.
The rectified DC is controlled by a 12V Zener diode then the controlled DC voltage appears near the sensor power supply section and also the relay. When any motion is detected the trigger passes the positive voltage to the 8050 transistor base pin and turns on the relay also the connected light. This circuit is perfectly suitable for bedrooms, Toilets, and also the outdoor light setup.
PCB Layout
