Energy harvesting, the practice of scavenging ambient electromagnetic fields, light, or other energy sources, is a fascinating subject that we don’t see enough of here at Hackaday. It’s pleasing then to see [Jeff Keacher]’s Christmas card: it’s a PCB that lights up some LEDs on a Christmas tree, using 2.4 GHz radiation, and ambient light.
The light sensors are a set of LEDs, but the interesting part lies in the RF harvesting circuit. There’s a PCB antenna, a matching network, and then a voltage multiplier using dome RF Schottky diodes. These in turn charge a supercapacitor, but if there’s not enough light a USB power source can also be hooked up. All of this drives a PIC microcontroller, which drives the LEDs.
Why a microcontroller, you ask? This card has an interesting trick up its sleeve, despite having no WiFi of its own, it can be controlled over WiFi. If the 2.4 GHz source comes via proximity to an access point, there’s a web page that can be visited with a script generating packets in bursts that produce a serial pulse train on the DC from the power harvester. The microcontroller can see this, and it works as a remote. This is in our view, next-level.
Now if it just had an e-ink picture that moved…
Wow, it also looks like a nifty microwave oven RF leak detector.
Because the article doesn’t explain very well..
It’s a contactless and batteryless device that can both be powered by and communicate bidirectionally (camera?) with your phone.
16 uW at high power mode and 0.4 uW on low power mode.
Super cool.
Guess, that is power consumption not minimum RF input power as the only power source ?!
Otherwise it would be far beyond what scientific projects achieved at that frequency.
In case I’m wrong where did you find that?
Peter/DL3PB
Cookies got you eh? Hopefully mods will delete the double comment below.
Yes it is consumption. Got it from the link in the part where it is dicussing clock freq. changes.
Where are the links to build it or buy it?
https://github.com/teuobk/xmas2024
GitHub repo for the code. No HW design files or license yet. I totally want to build one to learn this design style.
License added, no hw design files up yet
I do hope they are put up – this is one of those very cool projects that come around every couple of years that I would like to buy or build.
His page says he built 100 of them (by hand), likely for friends and family (for Christmas… the whole point of it being a 2024 Christmas ‘card’ !!) so unlikely to ever become a mass market thing.
The firmware & schematics are there, SO, an upvote for putting the full design up!
I am also interested in obtaining this. Would be awesome at the office.
Regarding the microwave oven detector, I’ve used a 1N21 and a current meter to measure leakage from an oven.
The espionage that could be (or is) done with. Someone hands an innocent looking business card encasing this circuit. The target carries it into their office building. However, this one has a micro supercapacitor that harvests and stores power to run a microprocessor with malicious code. The supercapacitor stores power and at a predetermined time powers the microprocessor circuit launching a hack on the carrier’s network system. Ok, so I have been watching Mission Impossible too much…
Today I can suppose that a bug the size of a rice grain exists and used if needed, but is much more easier to hack mobile phones or computers or cameras. Not of the target perhaps but of the neighbours (as seen in a previous article). Or you hack pe power grid to send signals to the electrical equipment that has been configured to receive sound and electromagnetic waves for storing and forwarding.
Network of any sort is the key those days.
In less than 5 years you’ll step onto the bugs on the street, carefully layed by some delivery robot, then you’ll carry them around as they will record your activity.
In 10 years (as an old sf novel predicted), you’ll breathe the bugs. They will spy and control you.
I don’t think that Tom Cruise Mapother IV OR V will be able to defend against those bugs and their masters, even in a movie. Unless V is a high upgraded clone cyborg and is called Katia Van Dees.
“I NEED YOUR CLOTHES AND YOUR BIKE”.
easy wrote: “16 uW at high power mode and 0.4 uW on low power mode.”
Guess that is power consumption not RF input power? Otherwise that would be by magnitudes better than the best scientific results. Could not find such in the technical documentation, which by the way is otherwise
excellent.
My own experiments worked down to 2µW RF power, but that was at much lower frequencies when efficiency is usually much better.
Peter/DL3PB
Yes it is consumption. Got it from the link in the part where it is dicussing clock freq. changes.
Prize worthy project. I love it.
This is witch craft.
+1000!!!