这This is an RC circuit with a series coil that controls the full current, making the relay work reliably, and reducing current and saving power.

    The highlight of this circuit is that by adding two of the most common components, a resistor and a capacitor, you can keep the relay coil closed steadily, even if the driving voltage is reduced, it doesn't matter. Ordinary electricians can be quite troublesome, take a look at our simple solution.

The power consumption of the relay coil can be reduced by capacitance and resistance

    The relay drives the transmitter stage of the transistor to ground, and we add resistors and capacitors to interrupt it. When the drive transistor is off, R2 ensures that the capacitor is discharged, and when the relay is on the drive transistor, the capacitor is equivalent to a short circuit, allowing the maximum current to pass through the relay coil and remain closed.
    When the capacitor is charged, the voltage and current in the coil drop, and when the current through the coil is transferred to R2, the voltage and current of the circuit are stabilized. Of course, even if the driving voltage is gone, it still stays closed. The resistance added is about twice the resistance of the coil, the resistance of 390 ohm, the coil of 200 Ohm. The capacitance is 150uF,