The only current specification I can find for the HC-SR04 is "quiescent current : <2mA".
I'm guessing that the active current draw is low enough that running 8 of them off the Arduino power rail would not be a problem.
The only current specification I can find for the HC-SR04 is "quiescent current : <2mA".
I'm guessing that the active current draw is low enough that running 8 of them off the Arduino power rail would not be a problem.