NewPing Library: HC-SR04, SRF05, SRF06, DYP-ME007, Parallax PING))) - v1.7

Using Arduino Sensors
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teckel:
Interesting! My ultrasonic sensors only use a couple mA each, while the Arduino Uno uses 60 mA (I'd guess the Mega uses more). I wouldn't think that just the sensors would put your USB or the voltage regulator over the top. Have you measured what kind of current it's using? It just seems very unlikely that it's within a couple mA of going over the top and the sensors draw enough current to do it. I guess it's possible, just doesn't seem likely.

Tim

Well it did it for me at least. Hopefully it helps someone else as well.

The operating voltage for the HC-SR04 should apperently be 4.50 to 5.0V. But I did some quick measurements which shows that that's not the case for my sensors:

With Ethernet shield:

  1. Power via USB port
    1.1. With LCD screen connected as well, at 3 HC-SR04 ultrasonic sensors: 4.55 V
    1.2. Without LCD Screen: 4.60 V

  2. Power from power outlet
    2.1. With LCD screen connected as well, at 3 HC-SR04 ultrasonic sensors: 4.98 V
    2.2. Without LCD Screen: 4.98 V

Without Ethernet shield:
3. Power via USB port
3.1. With LCD screen connected as well, at 3 HC-SR04 ultrasonic sensors: 4.76 V
3.2. Without LCD Screen: 4.82 V

  1. Power from power outlet
    4.1. With LCD screen connected as well, at 3 HC-SR04 ultrasonic sensors: 4.98 V
    4.2. Without LCD Screen: 4.98 V

i.e. since it doesn't work properly for me with just the sensors and the Ethernet shield connected (using just USB), over 4.60V seems to be needed.