PWM-to-analog converter for pneumatic control

While developing a compressed-air cooling system for Bloft Mk2, I encountered a mismatch between two control interfaces. The printer's mainboard provided a PWM output intended for a cooling fan, while the proportional air valve required a 0–5 V analog input.

2023
My role: Circuit development, PCB design, CNC milling, assembly and testing
Tools: KiCad, FlatCAM and CNC milling
PWM-to-analog converter in its ventilated enclosure

Making the interfaces work together

I used an off-the-shelf PWM-to-voltage converter as the starting point. The printer's output needed to be inverted and isolated before reaching the module; without that additional circuitry, interference affected its operation.

Top side: power and interface circuitry.
Top side: power and interface circuitry.
Bottom side: PWM-to-analog converter module.
Bottom side: PWM-to-analog converter module.

From breadboard to a milled PCB

I built and tested the circuit on a breadboard, then designed a two-sided PCB in KiCad. After preparing the milling paths in FlatCAM, I made the board on our CNC machine and assembled the components.

CAD animation of the converter PCB assembly.

Producing the board in-house made it possible to iterate on the prototype without waiting for an external PCB order.

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