I’m looking to control a handful of 12V PC fans using the digital outputs, switching outputs on/off to control fan speed.
The manual states that max switching current is 100mA, but my fans draw 300mA and 700mA.
I gather that I will need to add transistors to the outputs, but I have ZERO experience with them.
Can anyone give me some pointers?
You can use the PWM outputs of the K8055 too to control the motor speed.
Please see this thread for the circuit diagram: viewtopic.php?f=3&t=3899
You can use similar circuit if you use the digital outputs too.
On p.2 there is some pictures how to fit the transistor to the heat sink.
You do not need as huge heat sink anyhow.