Smooth LED fading via PWM

[RossWaddell]

Only if using PWM on a PIC pin , you can directly drive a transistor base without a resistor.
That will save you one component (resistor) and also space on PCB.

If you use Mosfet with PWM, you can also directly drive the gate without resistor. But this time, you need to have a resistor between the gate and GND. This resistor is not needed if not using PWM.

Hi sayzer - I've been working on driving up to 10 LEDs with a BS170 MOSFET and have connected the PIC pin directly to the gate of the 'FET. I had seen a circuit diagram with a resistor connecting the PIC -> gate to end, but then heard that this wasn't needed. What size resistor should I use?

[Ioannis]

Not necessary to add resistor to Fet gates.

Only if you had bipolar transistors.

Ioannis

[RossWaddell]

Thanks heaps, Ioannis.