Carlos 20 March 2014 / 18:03 What do you mean by saying they are not essential? They are! Otherwise you may burn the transistor (or the Arduino)
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What is the reason for having the 1k R9, R10, and R11 resistors?
Current limiting but they are not essential.
What do you mean by saying they are not essential? They are! Otherwise you may burn the transistor (or the Arduino)