So in Australia its hard to find good smart fan controllers. Before you all jump in and tell me what an idiot I am let me clarify.
Ceiling fans have 2 types of speed controllers.
The first of these is the Switched capacitive controllers where usually there are 2 capacitors (or 2 in one package with 3 wires) that provide L and M speed by adding a small and medium sized capacitor in series with the 240v AC supply, and H is straight 240v AC to the fan motor. The pros and cons of such an approach are that 1) Con, there are only, in the case I mentioned, 3 speeds, and the values of the capacitors needed to achieve what you want for M and L speeds depends on the size of the fan/motor and your own personal preferences. 2) Pro, The capacitive speed approach delivers a reduced speed with very little motor noise…this is important if the fan is in your TV room or bedrooms etc.
The second controller type is the infinitely variable speed controller that uses an active device like a Triac to cut chunks of the sine wave off so that the energy contained in the sine wave is reduced, and so too the motor speed as chunks of it are cut off. The Pros and Cons 1) Pro, what ever speed you want you can get 2) Con, the slower the speed the more noise the fan produces. In AU our supply frequency is 50Hz and 50hz hum in a TRIAC driven motor just sucks big time. My wife is a light sleeper and these types of controllers are not acceptable in a bedroom for her.
One of our big hardware chains sells the “Grid Connect” series of smart controllers and within the range there are capacitive controllers available but the caps are all 1uF in size and configured so that low is 2 of them switched in, in parallel and medium is all 3 in parallel so achieving a 2uF and 3uF size. If the fan in my bedroom was the size needed for the largest lounge living room then the speeds achieved would be good for a bedroom with a 6+ft diameter fan but for my normal sized bedroom where flat out is Mach 1 then these values achieve Medium of 0.99Mach and 0.95Mach for Low… I swapped out the 3 x 1uf CBB style caps in the controller which were IMHO a bit too close to supply voltage for my liking (305VAC ) with some 0.7uF 450VAC CBB caps and I now have a working solution … All good… and then I got to thinking…
The very expensive $60 fan controller at the end of the day is simply 4 switches in one (1 Light and 3 for fan speed) … we can buy plain old 4 switches in one controllers and simply add our own capacitors to achieve the same outcome.
Also note that while consumer fans only have 2 capacitive speeds and one flat out speed because they use a 4 position rotary switch where 1 position is off there is no electrical reason why that is all that can be available.
If you set up a wifi or zigbee (or whatever) multiple switch, switch bank so that each output (L or A out) feeds into an appropriate capacitor is series with the motor, and one that simply feeds out without the capacitor in series (representing flat out) and parallel all of the other ends of the capacitors with the straight out wire and then connect this to the fan motor then as you switch in (on) each capacitor the capacitors will add in parallel and the fan will get faster and fast and finally when you switch in the straight through connection the caps will be bypassed and youll get flat out. To be clear, off will be all switches off, L will be the one switch L ON. ML will be L and ML ON, MH will be L, ML,MH all ON and finally H will be all on (or at least the one switch that doesn’t have a capacitor in series). If you only ever switch one switch on then you will need a unique capacitor value for each switch and buying 4 different capacitors will cost much more $ than buying 4 of the same.
In my case I know that I need 1.4uF to get the slowest speed needed so I would add a 1.4uF cap (2 x 0.7 in parallel) to one switch. I know that as I add 0.5uF(or 0.7uF in my case) i Get an appreciable change in speed, so I would add 2 separate channels each with their own 0.5/0.7uF cap and finally the straight through channel. So 4 channels in all. Have it so that the 1.4uF switches in 1st, then add 0.5uf then another 0.5uf and then finally the straight through and you get L-ML-MH-H.
I purchased off ebay 5 x 0.7uf caps for $12 AUD and a 4 channel Zigbee switch is available for $20AUD that makes a cheap and more capable controller than anything else available to do the job.
For all those that do the “OMG that’s 240V AC mains and it’ll kill you!!”…yes it potentially will…so like all experimental projects that involve mains supply treat it with respect and only undertake it if you know what your doing. Consider things like risk to your insurance paying out… and fire risks and bolts of lightning from the heavens as you do…
Andy