Boost to 12V

Projects General Guidance
21

wvmarle:
28 mA is a lot for a pin to source. They're not meant for that. Also you forget that 28 mA at 12V is a lot more current are 5V.

It's best to split your usb cable and bypass the Arduino for power supply to your 12v converter. There are ready made converters that plug in to a USB port (the converter is built into the USB plug) and provide 12v output. Very convenient.

You can also get DC/DC converters for 12-15v to 5v, handling your variable power supply just fine.

Thanks for the response. I still don't see why driving a pin at 70% of its designed maximum (28mA vs 40mA max) is an issue. But I don't want to be accused again of just debating something. Hence, I will just assume that it's just considered a bad idea to get more than 50% of what the specs allow and adjust my future designs accordingly.

As for splitting the USB cable, I will definitely try that. So basically I will cut the cable. Then I do a Y for each of the wires in the USB cable. One side will be connected to a new USB connector that goes into the DC/DC converter with a USB plug (or just a DC/DC converter with pins). The other end I will connect to the original USB connector (the one I cut off) and then plug that into the Arduino board.

22

Well yes you can draw 28 mA from a pin. That still doesn't mean it's a great idea - how about switching peaks? Direct power supply is better.

But you want to connect it to a booster to supply 28 mA at 12V to your transmitter. That means you need to provide about 70 mA to the 5V input if the booster, and that will result in a fried digital pin.