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this post was submitted on 05 Dec 2023
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That is mind-blowing.
Last time i saw a product claiming to run on energy harvested from radio-waves, it was a kickstarter project that (surprise surprise) turned out to be a complete scam.
It is totally possible to harvest energy from radio waves, it's just such a tiny amount that you could barely light a LED
Yeah that's my point, the energy you can actually harvest is ridiculously small. Even if it was slowly charging a capacitor with this harvested power and saving it for later use, how often can i use the switch before depleting the energy faster than it charges? "oh sorry, you'll have to wait 5min to turn on your lights again, It's not quite charged enough"
My guess is you would get a couple seconds of light before needing several hours to charge it up again.
Not really. RFID operates the same way and has been around forever at this point. This whole thing is a gimmick, it doesn't replace switches it just makes them more complicated and moves where they're located. To switch mains current you're going to need a relay which is more expensive than a simple switch and then you're going to need to somehow tie a particular RF switch to the appropriate relay.
Sure you might be able to reduce the length of wire running through the walls a tiny bit, but that's going to be offset by a significantly more expensive and complicated control circuit somewhere. The only way this makes financial sense is if the cost of copper gets so high that running an extra 50 feet of wire is more expensive than a series of microcontrollers and relays and the unreliability of using RF for control.
If true, that application goes WAY beyond light switches. Really burying the lede here.
I've heard of this before but I think it's really a trickle charge. Not practical for charging a phone or anything like that.
I have a Philips Hue wireless switch that has no batteries. The click action when you press the button is enough to drive the transmitter. The button moves in about 4-5mm when pressed and that is all that's needed to drive the transmitter.
What's really mind-blowing is that such trivial amounts of energy runs a transmitter that sends a specially coded pulse (not even just an on off pulse of RF) thirty feet to the receiver.