Pwm fan on zynthian

is what it all fitted in so it needed a fan that would fit the mounting points in the case so it needed to be 25mm * 25mm
I bought a 5V one from amazon which didn’t have any fancy PWM connections or such like, and fitted it, directly to the 5v line in the Pi.

It was LOUD … :-(, disturbingly so…
so I connected it to 3.3V which was much more acceptable, but since I leave my zynth’s on most of the time this seemed a pretty effective way of chewing the bearings up pretty quickly.

So I added a BC108 in the 0V side of the circuit with the emitter connected to 0V & the collector connected to the ov side of the fan and drove it from GPIO 14 on the edge connector.
This was all assembled on a small bit of veroboard and joined to the appropriate pins with thin wires with heatshrink over it to avoid shorts and the GPIO pin driving the base of the transistor via a 680 ohm resistro.
Fire up the Pi and go into the performance section and enable the fan, setting the temperature to 60 degrees and hey presto, the fan starts up with the Pi then turns off as the green LED starts to flicker.
A soon as the Pi reaches 60 degrees on comes the fan, which I’m still connecting to the 3.3V rail. Not a problem as there isn’t any thing else connected to the GPIO header in this zynth ( a 60 W amplifier known as zynthian-amp4.local).

We are using it for piano and strings via MIDI and also for playing backing tracks for a wedding.
Seems pretty good, and the temperature settles around 55 degrees or so.

I wont put up the veroboard as it’s not the nicest piece of work, held in place using one of the Pi boards mounting screws, I’ve ever done but it fits in the case and works … !

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