Venta Connected

Adding WiFi control to a Venta LW45 humidifier using a custom PCB with a ESP8266

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In this project, I'm designing a WiFi-connected PCB that adds remote control capabilities to an old-school Venta LW 45 air humidifier.

The control panel - connected to the main PCB via a 10-pin ribbon cable - of the humidifier provides five LEDs indicating power status, level and error and two buttons to turn the device on/off and to change levels. I insert my own custom PCB where the ribbon cable is plugged in, thus allowing me to read out the HIGH/LOW status of each cable pin as well as pulling down each cable pin emulating a button press.

As the Venta LW45 is powered through an external 24V power supply, I tap into that power source, but need to convert to 3.3V for the ESP8266 that is used to provide the WiFi control.
To read out the status of the LEDs, I use LM339 / LM393 dual / quad differential comparators and to emulate button presses, I'm using three 2N7000 FET transistors.

More details about this project can be found in my extensive blog post:


Schematics of the WiFi control board for the Venta LW45 humidifier

x-kicad-schematic - 1.81 MB - 10/14/2018 at 14:59


Zip Archive - 133.67 kB - 10/14/2018 at 14:59



PCB design of the project

x-kicad-pcbnew - 536.70 kB - 10/14/2018 at 14:59



Schematics of the WiFi control board for the Venta LW45 humidifier

Adobe Portable Document Format - 27.67 kB - 10/14/2018 at 14:59


  • 1 × ESP-12e WiFi mofule
  • 1 × LM339 quad differential comparator SMD SO14
  • 2 × tactile switches SMD 6x3.5mm
  • 1 × 2x5pin boxed header male, 2.54mm pitch, through-hole
  • 1 × 2x5pin header female, 2.54mm pitch, through-hole

View all 13 components

View all instructions

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