How to Cut off power for HC-SR04 Ultrasonic Sensor using Transistor (Effective way of Switching)

 Here PN2222 Transistor BJT is working as a switch.

Use  Below Circuit to Switch the Ultrasonic Sensor.

Connection :

Use NPN PN2222 Transistor.

1. Connect Base of the transistor with 1K resistor to digital output of the micro controller. 
1. whenever you provide an output to the Base HC-SR04 will get power. if base has no input supply, HC-SR04 will be on off condition which here referred as a power saving mode.
2. Connect Collector of the transistor to ultrasonic sensor GND
3. Connect Emitter to GND of the battery or Controller GND

Any Doubts comments below…..