I heard you like homeautomation? First I liked to buy myself a “smart fan”, but since they’re expensive (~120 €) I cheaped out.
Therefore I bought a 20 € IR-controlled pedestral fan with the first goal to control it via tasmota-ir. But how to check the current status (speed) then? Well, let us open the device and check the internals.
!Warning! I’m a electrical engineer and know what I’m doing. Working with mains-voltage is very dangerous. This is no guide and I won’t recommend to rebuild it by yourself! That’s why I don’t say any detailed infomation about the used parts and their connection. It only should show the process in converting devices roughly.
First I was shocked how many empty space there is in this thing! Fortunately a lot of space to include my own electronics. Unfortunately everything on the one-sided PCB runs directly on mains-voltage or with some voltage-dividers and mixed AC/DC voltages. Therefore it’s difficult to manipulate them with DC-devices like the Wemos D1 mini directly.This is why we need a solid DC-supply first. I searched for the smallest supply, which was an old iPhone-charger. I checked the model-number (there are some versions, which have a high risk to spontaneous burn down) and connected a old USB-A-cable to it. The input is soldered directly to the fused mains-input of the fan and is isolated to prevent shorts.
To isolate the new low-voltage DC circuit from the rest of the PCB I then used optocouplers (they transmit signals with no electical contact via light) to “press” both buttons via the wemos. The first one does “On/Speed” and thus cycles the speed (Low, Mid and High). The second “Off” one turns everything off.
To get informations about the real speed I connected optocouplers to three control-lines which corespond to three speed-LEDs. They trigger a signal at the wemos which send the information to a MQTT-Server.
After isolating and assembling everything it was time to show off the new smart-thing.The video shows a basic test via the tasmota-interface. The relais-mode is self resetting to simulate a button-press. Time to integrate it into HomeAssistant and NodeRed.
I hope it was interesting and inspiring.
old iPhone-charger for 5 VDC
Test assembly for wemos and optocouplers
Everything isolated for assembly
Test control via tasmota-interface