Doubt about buck converter

Hi guys :slight_smile:

I saw this on http://www.instructables.com/id/Arduino-based-Switching-Voltage-Regulators/

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My noobiness surely is missing something obvious… :grin:

Can someone please explain me why there’s the need for the NOT gate there? - i.e. why not connecting the bases of Q2 and Q3 directly to the Arduino’s output (through a resistor of course)

Thanks in advance :wink:
Pedro

Because the Arduino doesn't output 12V signals. The first FET is a level shifter, the two BJTs are a high current buffer (class B amp). The p-channel power FET needs 12V high current drive.

"level shifter" acted as a keyword and made me google it (another lesson learned ;) )

Its usefulness clicked immediately :P

Appreciated Mark, karma going your way ;)