Designing a PWM to Analog mini board for fans

Hello all!
I'm building a custom toolchanger with e3d toolhead and toolplates, and I was having problems with fans not reacting to PWM or being very whinny/loud/weak as soon as I PWM'd them, so I'm designing a very simple circuit with an low pass configured opamp and a transistor that should give a nice and stable analog voltage from the PWM signal from the duet.

Since I'm lowpass filtering in small signal, no inductors are needed, just a couple of resistors and capacitors, EMI should not be a problem, and the pcb should be very small.

My aim is just to use an all 24V system, but it would be rather easy to make the circuit voltage-agnostic so you could be able to mix and match fan voltages in the future.

Is anyone interested in such a circuit? I'm thinking about having some pcb boards manufactured, and since most services are about 20 pieces minimum order, I will have plenty of them...

Any thoughts?

Also posted this in duet forums (hope it does not break any rule...)
[forum.duet3d.com]

Posting should be fine, since its not a device for printer-only-use. I will link it up to the german forum, i think there would be some interest on our side there too.
Me being too dumb to develop electronics by myself would have uses for it, that are soley outside of 3D-printing.
So yes, i'm interested .

/Julien

Edited 1 time(s). Last edit at 02/19/2021 08:01AM by ZipZap.

---

Wer rasiert mit mir KingKong? Der wichtigste Guide - Triffid Hunter's Calibration Guide

---

---

Drucker:
CoreXY in 250²x300 - geschlossen & beheizt für ABS - Duet2WiFi - Eigenbau Wasserkühlung
Eigenbau I3 - V6-Clon- Profilrahmen - Ramps 1.4 24V - TMC2208 - Simplify3D - Octoprint - Marlin 1.1.8