Why does LilyMini only output 7mA?

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I couldn’t figure out why the LilyMini cannot power a simple [vibrating mini motor disc, when the switched LilyPad Coin Cell Battery Holder can. Then I used my multimeter and found that the coin cell holder outputs 2.9V at 200mA, but the LilyMini only outputs 2.9V at 7mA. The motor disc requires at least 40mA to work.

I think it’s a real shame the LilyMini doesn’t output more amperage. It would be so much fun to use it in small sized projects for more than just LEDs.](Mini Vibratie Motor Schijfje | Kiwi Electronics)

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It’s a limitation of the processor used (SAMD11). See table 35-11 in http://ww1.microchip.com/downloads/en/d … asheet.pdf

It will go down to 2mA as the voltage drops. You can add a transistor to switch larger loads.

/mike

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Thanks for clearing that up! I think I’ll use a different microcontroller.

But I’m curious how this would work. Could I used a transistor to amplify the amperage without using a separate power supply?

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Like this, I guess: http://www.learningaboutelectronics.com … ircuit.php

I will give this a try, for fun

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Could I used a transistor to amplify the amperage without using a separate power supply?

Yes, a small NPN transistor like a [2N3904 would do the trick. I don’t have a guide specifically for the LilyMini, but this transistor tutorial would give you an idea how to connect things. You’re just using the + and - pads on the LilyMini in place of 5V and GND in the tutorial.

The small current output from the LilyMini turns on the transistor and that passes the larger current your external device needs to operate. If you’re using a motor, (inductive load) don’t forget to use a [small diode across your motor terminals to protect the transistor.](https://www.sparkfun.com/products/8588)](https://www.sparkfun.com/products/521)

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Thanks! Your link is directed to this thread though, not a tutorial page. :wink: