First of all, I'm sorry for the newbie question. I'm a software engineer and only a hobbyist in electronics.
I'm trying to power up an external circuit using an Arduino digital pin.
The external circuit uses a 12V power source and drains about 4mA. I have successfully done this using a transistor.
According to the specs, the Arduino digital pins can supply up to 20mA with no problem.
Therefore, I was wondering if it is possible to power up this circuit directly from the pin, without using the transistor, nor the 12V external source.
The questions are:
1) Is it possible? How can I accomplish this?
2) What about the higher voltage? I think the circuit is designed to work with 12V and if I supply a lower voltage it should drain less current (according to Ohm's law) and the current wouldn't be enough. Does it makes sense?
3) If (2) makes sense. Is there any trick to do to achieve this needed higher voltage from the pin?