Human body infrared sensor module to connect the electrical method
2 then the transistor 8050 B your relay's normally open contact one end of the transistor C transistor E pin connected 0V
Typical applications are right. You can add a step-down resistor 9V down to 3V, and then connected to the relay.
First determine your 3v relay coil operating current is how much, if not found, you can use a regulated power supply to 3V string into the multimeter (current) access to the relay to pull, write down the current value, if it is 0.1 A, as the downstairs hby8401 said, we have to calculate the current limiting resistor = (9-3) /0.1 = 60 ohms, its power 0.1 * 6 = 0.6W, select at least 1W above 60 ohm resistance access board 1 foot To the top of the relay (diode negative in the figure), and the transistor emitter connected to 3. The base of the limited current resistance directly into the 2 feet bar.
