I will be using all of the following sensors at the same time on raspberry pi b+ model with 2Amp power supply.
1) DHT-11 Digital Temperature & Humidity Sensor for temperature and humidity measurement
2) HC-SR501 PYROELECTRIC INFRARED PIR MOTION SENSOR for motion sensing
3) Soil Hygrometer Humidity Detection Module Moisture Testing Sensor for soil moisture
4) HC-SR04 Ultrasonic Distance Sensor for measuring distance
I'm not sure whether the current will be enough for all the sensors and a wifi adopter connected to it. So can I supply current externally to HC-SR04 Ultrasonic Distance Sensor(needs 5V) and the HC-SR501 PYROELECTRIC INFRARED PIR MOTION SENSOR (needs 3.6V) through a DC power supply