Where This Xmas Card’s Going, We Don’t Need Batteries!

December 19, 2024 by Jenny List 16 Comments

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.

3D Print Your Own Seiko-Style “Magic Lever” Energy Harvester

August 9, 2023 by Donald Papp 20 Comments

Back in 1956, Seiko created their “magic lever” as an integral part of self-winding mechanical watches, which were essentially mechanical energy harvesters. The magic lever is a type of ratcheting arrangement that ensures a main gear only ever advances in a single direction. [Robert Murray-Smith] goes into detail in this video (here’s a link cued up to 1:50 where he begins discussing the magic lever)

There is a lot of naturally-occuring reciprocal motion in our natural world. That is to say, there is plenty of back-and-forth and side-to-side, but not a lot of round-and-round. So, an effective mechanism for a self-winding watch needed a way to convert unpredictable reciprocal motion into a unidirectional rotary one. The magic lever was one way to do so, and it only has three main parts. [Robert] drew these up into 3D models, which he demonstrates in his video, embedded below.

The 3D models for Seiko’s magic lever are available here, and while it’s fun to play with, [Robert] wonders if it could be integrated into something else. We’ve certainly seen plenty of energy harvesting projects, and while they are mostly electrical, we’ve also seen ideas about how to harvest the energy from falling raindrops.

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Miracle Of Science: Scotch Tape Improves Generator

December 4, 2022 by Al Williams 11 Comments

We were always amused that one of the biggest scientific discoveries of the recent past — graphene — was started with pencil lead and Scotch tape. Now, researchers at the University of Alabama in Huntsville have determined that double-sided Scotch tape can improve triboelectric power generators. Triboelectric generation, of course, is nothing new. These energy harvesters take mechanical and thermal energy and turn them into tiny amounts of electricity. What’s new here is that PET plastic, aluminum, and double-sided tape can make an inexpensive generator that works well.

Keep in mind we are talking about little bits of power. In the best scenario with the device stimulated at 20 Hz, the generator peaked at 21.2 mW. That was better than some designs that only got to 7.6 mW in the same configuration.

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New Part Day: The Smallest Batteries You Have Ever Seen

November 15, 2022 by Jenny List 17 Comments

We’re used to some pretty small batteries in miniaturized electronics, thanks to the manufacture of lithium-polymer pouch cells. But they’re still pretty big, and they’re hardly the most stable power storage solution. The French company ITEN may have an answer for designers of micro-power devices though, in the form of a range of tiny surface-mount solid-state rechargeable lithium batteries. These come in a range of capacities from 0.1 mAh to 0.5 mAh, and in a 3.2 by 2.5 mm package look very much like any other slightly larger SMD chip component.

These devices are most likely to be found in applications such as remote wireless sensors, where they can store the energy from a small solar cell or similar to produce the burst of power required to transmit a packet of data as well as the tiny current required to keep things ticking over. The solid state chemistry should provide a long life and lack of leaks. For now they have some evaluation kits on offer, and unless we missed something, no full data sheet. We’d be particularly interested to learn about their temperature sensitivity when it comes to soldering, as we’ve taken to heart the warnings about soldering to more traditional lithium cells.

Via CNX Software.

Less Is More When It Comes To Sensor Power

October 25, 2022 by Al Williams 26 Comments

It used to be the cost of a microcontroller was a big inhibitor to putting brains in everything, but those days are long gone. Even 32-bit CPUs are now cheap enough that you can throw them into anything. The biggest factor now is probably power. Do you really want to charge your electric toilet seat or change batteries every few weeks? A company called Everactive wants you to ditch your battery using their sensor platform they claim harvests energy from a variety of sources and they are about to deliver their first developer’s kit.

The sensor can measure temperature, humidity, pressure, magnetic field, and acceleration on three axes. The device claims to harvest energy from radio frequencies, vibrations, small temperature differentials or light, even indoors. Our guess is that the sensor package runs on very little and when you poll the device wirelessly, the incoming radio signal supplies power for communication. The company claims its device uses 1000 times less power than competing solutions.

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Human Power, Past And Future

March 1, 2022 by Al Williams 54 Comments

We will assume you’ve seen The Matrix — it was from 1999, after all. The surprise, at the end, was that humans were being used as human batteries to power a civilization of intelligent machines. But aside from just putting out some heat, the idea does have some precedent. After all, humans powered machines like mills, sewing machines, and pumps for centuries before there were good alternatives.

History

Galley ship — Reconstruction of a squadron of ancient Greek galley ships.

Early machines used hand cranks, treadwheels, treadles, and even pedal power to harness energy from humans. Consider, for example, an ancient galley ship with many oarsmen providing an engine. This wasn’t a great use of human power. An oarsman on a galley used his arms and back but didn’t much use his legs. The legs, though, have larger muscles and are often stronger. A pedal boat or racing shell would have been much more efficient, but without mass production of strong metal parts, it would have been difficult to build and maintain such machines in ancient times.

There was a time when pedals or treadles operated lots of machines from sewing machines to lathes. There were even old radios able to transmit and receive with no external power thanks to pedals as late as the 1940s.

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Power For Nothing And Your Kicks For Free

January 30, 2022 by Al Williams 68 Comments

We all know that you can convert heat into electricity. Usually, you do that with some form of steam, but there are other methods, too, including thermocouples. If you’ve ever seen something producing waste heat, you’ll appreciate Penn State’s work to harvest power from hot pipes. The idea is simple in theory: create a flexible thermoelectric generator that can wrap around hot pipes or other surfaces to gather otherwise lost heat. The full (paywalled) paper is also available.

The devices can produce up to 150% more power per unit area compared to other thermoelectric generators. A three-square-inch test device produced over 50 watts. Scale that up to an industrial pipe hundreds of feet long, and you could create some serious power. To accomplish this, the scientists used strips of six thermocouples and connected them for a total of 72 thermocouples. Liquid metal between layers improved the device’s performance.

This isn’t a totally new idea. Russia was famous for making radios in the 1950s that operated using a generator that went around the flue of a kerosene lamp. Since the Russians were pulling this off in the 1950s, converting heat into electricity is obviously nothing new. Of course, your body creates heat, too, so why not use that?