On our most recent IoT Podcast, Dan called into our IoT voicemail hotline with a question about controlling the speed of a small personal fan using a smart outlet. Dan wants a Wi-Fi outlet with dimming capabilities so he can increase or decrease the air flow with a digital assistant.
On the surface, this sounds reasonable and logical. After all, there are outlets and switches that can dim lights by limiting the flow of energy to the bulbs. But variable speed fans are not bulbs. In fact, you could burn out the fan or, in a worst-case situation, cause a fire by trying to use some type of dimming mechanism to control the speed of a fan. So in short: don’t do this!
Powering a motor, such as that in a fan, requires a lot of electricity up front in order to get the motor up to speed quickly. And most motors with variable speeds use some sort of variable frequency drive; something a dimmer control isn’t capable of doing. Put another way: Unlike limiting the flow of power to dim a bulb, for a fan, you need to convert power into some mechanical or moving action that will typically require wide-variances of power immediately. It’s simply not the same as a bulb.
All is not lost, however! We did find a few Wi-Fi-enabled pedestal fans available on Amazon. This one from Nash (shown above) is $95, for example, and a similar-looking option by Wasserstein is available for $60. Both work with Amazon Alexa and Google Assistant, so along with an app, you can bring up the breezes by voice as well.
To hear Dan’s question, along with our discussion in full, tune in to the IoT Podcast below:
There are three main types of dimmers — trailing edge, leading edge and sine wave. Light bulbs want trailing edge dimmers. Motors and power supplies (ELV halogen) want leading edge. Sinewave is more expensive but it can handle both motors and light bulbs. The waveform in some dimmer is even programmable and they can be adjusted to make all three waveforms.
I would like to see the industry stop making TRIAC based dimmer and move over to MOSFET based sine wave. That’s because you can dim an LED bulb down all of the way with a sine wave dimmer and you can’t do that with a trailing edge dimmer. That is kind of non-intuitive since you can dim an incandescent or halogen bulb down all the way with a TRIAC dimmer. The reason it does not work on LED bulbs is because LED bulbs have electronic power supplies inside of them which can not be fully dimmed on a trailing edge dimmer – you need sine wave to fully dim them.