You cannot use the 5V from the USB to power up the transistor and the LOAD because the USB port usually delivers only 100mA, and this is not enough to switch the relay and the LOAD. That is why you ...

Connect the GND of the battery to the GND of arduino – common GND. If you are using a 5V relay instead of 12V relay, you only have to connect the arduino GND. I am using a 12V relay. So the coil ...

Besides the mosquito killer, which plugs into a wall socket, he used a real-time clock (or RTC module) to report the time, a relay shield for controlling the on/off state of the mosquito coil, the ...

It’s a fairly simple project, too: just hook an Arduino Uno up to a motion sensor and an electronic switch called a relay, then plug in your fan, and you’re good to go.

Arduino Uno. 4-channel relay module. PIR motion sensor. Steps: Use Arduino to handle sensor input and relay control. Pi runs a Python Flask server with a simple UI to toggle GPIO pins via serial ...