bornach
The LED driver circuit is not the recommended way one would typically control an LED array using the a microcontroller GPIO pin. The current limiting is achieved by keeping the NPN BJT (C945) in its linear region by using a 18K ohm resistor on the base. This saves us a current limiting resistor but results in more heat dissipation by the BJT. I didn't really need to do this, but I just wanted to see if such a setup would work. Might come in handy if your parts bins lack resistors of the required value for current limiting.
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