Power for Devices

Hello, this is probably a general question, but my current use case is an ultrasonic sensor. I bought the sensor from Adafruit that is rated for 3.3v. It works great when my Microbit is plugged into the computer. It does not work on battery pack ;-(

When the MB is plugged into the computer, I read 3.2v between the 3v and GND. When I only plug into the battery pack (with fresh batteries), I only read 2.8…hence the reason the ultrasonic no longer works.

I am a trained programmer and school of hard knocks electrician. I assume this convo has to do with current and amps as well. Can anyone shed light on this behavior between the two power sources?



What type of battery pack are you connecting?
How are you connecting it to the Micro:Bit?

Standard 2xAAA battery pack to power the MB. When adding extra power, I use 4xAA like this:

The question is still why the difference between USB power from the computer vs. the standard 2xAAA?


With lots more research, looks like USB provides 5V and the on board regulator turns it into 3.3. So with more input voltage, I assume it can maintain higher currents, hence the reason USB acts more powerfully than a battery pack. Am I understanding this correctly?