The Cult Of Really Low-Power Circuits: Scrounging, Sipping, And Seeing Power

February 3, 2020 by Ted Yapo 19 Comments

If you’ve ever tried to make a really low-power circuit — especially one that runs on harvested power — you have probably fallen into at least a few of the many traps that await the unwary in this particular realm of electronic design. Well, Dave Young has been there, seen the traps, and lived to tell about it. In these territories, even “simple” systems can exhibit very complex, and sometimes downright confusing behavior when all possible operating conditions are considered. In his 2019 Hackaday Superconference talk: Scrounging, Sipping, and Seeing Power — Techniques For Planning, Implementing, And Verifying Off-Grid Power Systems, Dave discusses a number of these issues, how they interplay with low-power designs, and tricks he’s collected over the years to design and, more importantly, test these deceptively simple systems.

Dave is an electrical engineer and his company, Young Circuit Designs, has worked in the test and measurement, energy, and low-power consumer industries. We were lucky to have him share some of his 15 years of experience on the Supercon stage this past November, specifically discussing devices powered from harvested energy, be it wave energy (think oceans not RF), thermal energy, or solar. The first lesson is that in these systems, architecture is key. Digging deeper, Dave considers three aspects of the architecture, as mentioned in the talk title: scrounging, sipping, and seeing power.

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Teardown And Analysis Of A Cheap Solar Lamp

January 26, 2020 by Jenny List 57 Comments

If you walk the aisles of a dollar store one constant that you will see worldwide is the Chinese solar lamp. Your dollar gets you a white LED behind plastic, mounted on a spike to stick into the ground, and with a solar cell on top. It charges in the sunlight during the day and then lights the LED for a few hours at nightfall. They are in gardens everywhere, and no doubt landfill sites are full of them because they do not last very long. [Giovanni Bernardo] had one that stopped working, so he subjected it to a teardown to find out what was up, and what made it tick (Italian, Google Translate link).

As expected, the culprit proved to be a leaking and corroded 1.2 volt NiMh cell, and its replacement with an AA cell brought the lamp back to life. But the interesting part of this tale comes from his teardown and analysis of the lamp’s components. It’s centered around a YX8016 battery charger and power management chip. The device has an amazing economy of design with only four components including the solar cell and the LED. The final component is a small inductor that forms part of the boost converter to keep the LED lit as the battery voltage falls. The chip switches at 580kHz, and produces a 3.2 volt supply.

If this is a subject that interests you, don’t forget to take a look at the power harvesting challenge we ran a while back.

AMSAT CubeSat Simulator Hack Chat

December 2, 2019 by Dan Maloney 1 Comment

Join us on Wednesday, December 4th at noon Pacific for the AMSAT CubeSat Simulator Hack Chat with Alan Johnston!

For all the lip service the world’s governments pay to “space belonging to the people”, they did a pretty good job keeping access to it to themselves for the first 50 years of the Space Age. Oh sure, private-sector corporations could spend their investors’ money on lengthy approval processes and pay for a ride into space, but with a few exceptions, if you wanted your own satellite, you needed to have the resources of a nation-state.

All that began to change about 20 years ago when the CubeSat concept was born. Conceived as a way to get engineering students involved in the satellite industry, the 10 cm cube form factor that evolved has become the standard around which students, amateur radio operators, non-governmental organizations, and even private citizens have designed and flown satellites to do everything from relaying ham radio messages to monitoring the status of the environment.

But before any of that can happen, CubeSat builders need to know that their little chunk of hardware is going to do its job. That’s where Alan Johnston, a teaching professor in electrical and computer engineering at Villanova University, comes in. As a member of AMSAT, the Radio Amateur Satellite Corporation, he has built a CubeSat simulator. Built for about $300 using mostly off-the-shelf and 3D-printed parts, the simulator lets satellite builders work the bugs out of their designs before committing them to the Final Frontier.

Dr. Johnston will stop by the Hack Chat to discuss his CubeSat simulator and all things nanosatellite. Come along to learn what it takes to make sure a satellite is up to snuff, find out his motivations for getting involved in AMSAT and CubeSat testing, and what alternative uses people are finding the platform. Hint: think high-altitude ballooning.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, December 4 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Improved Outdoor Solar Harvester Now Handles All The Parts

November 19, 2019 by Donald Papp 6 Comments

[Vadim Panov]’s 3D printed solar harvester is in effect a rechargeable outdoor battery, and the real challenge he faced when designing it was having it handle the outdoors reliably. The good news is that part is solved, and his newest design is now also flexible enough to handle a variety of common and economical components such as different battery connectors, charge controllers, and solar panel sizes. All that’s left is to set it up using the GoPro-style mounting clamp and let it soak up those solar rays.

We saw his first version earlier this year, which uses inventive and low-cost solutions for weatherproofing like coating the 3D print with epoxy (the new version makes this easier and less messy, by the way.) It was a fine design, but only worked with one specific solar panel size and one specific configuration of parts. His newest version makes a few mechanical improvements and accommodates a wide variety of different components and solar panel sizes. The CAD files are all available on the GitHub repository but he’s conveniently provided STL files for about a dozen common sizes.

When it comes to harvesting light, staying indoors offers less power but requires a far less rugged setup. If that interests you, be sure to check out the Tiny Solar Energy Module (TSEM) which can scrape up even indoor light.

Azobenzene Stores Solar Energy

November 12, 2019 by Al Williams 30 Comments

Probably the most efficient way to convert solar energy into electricity is the old fashioned way, heating water into steam and turning a turbine. This remains a messy affair though and you don’t really want a steam boiler on your roof, so solar cells are popular. However, there’s some new research showing how a molecule can absorb solar energy, store it, and then release the heat on demand years later. This could offer new ways to collect and even transport solar power. This new molecule, derived from azobenzene, holds immense promise to change the way we work with solar power.

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ESP32 Makes Great MPPT Controller In Low-Cost Solar Installation

November 4, 2019 by Dan Maloney 34 Comments

Solar power projects have become, in general, a matter of selecting components like panels and batteries, hooking them together with industry-standard connectors, and sitting back to watch the free electricity flow. As such, solar projects have become a bit boring, so it’s not often we see one that attracts our attention the way this dirt-cheap open-source solar project does.

The backstory on [Tim O’Brien]’s DIY off-grid PV system starts with his desire to charge his eWheel, which amounts to a battery-powered standing unicycle. They look like a fun option for getting around an urban environment if you have the requisite degree of coordination, which we clearly lack. But charging something like that or an eBike is a great use case for solar, especially since [Tim] happened upon a 450W PV panel on the cheap. Sadly, the panel was a commercial unit, and compatible off-the-shelf MPPT, or maximum power-point tracking, controllers are expensive.

His solution was to build his own controller using a cheap DC-DC converter that just so happens to have serial remote control. An ESP32 monitors the panel voltage and controls the buck converter to run whatever he wants. When he’s not charging his eWheel, the system runs his laptop and router. As a bonus, the ESP32 talks to IoT services like Adafruit.io and Thingspeak, allowing him to track MPPT data without shipping it off to parts unknown.

While we appreciate a DIY MPPT controller and like [Tim]’s build, we feel like the documentation needs a bit of fleshing out. With solar installations, the devil is in the details, and not addressing seemingly mundane issues like cable routing and connector installation can lead to disaster.

Solar System Wars: Walmart Versus Tesla

September 19, 2019 by Dan Maloney 61 Comments

It seems like hardly a day goes by that doesn’t see some news story splashed across our feeds that has something to do with Elon Musk and one or another of his myriad companies. The news is often spectacular and the coverage deservedly laudatory, as when Space X nails another double landing of its boosters after a successful trip to space. But all too often, it’s Elon’s baby Tesla that makes headlines, and usually of the kind that gives media relations people ulcers.

The PR team on the automotive side of Tesla can take a bit of a breather now, though. This time it’s Elon’s solar power venture, Tesla Energy Operations, that’s taking the heat. Literally — they’ve been sued by Walmart for rooftop solar installations that have burst into flames atop several of the retail giant’s stores. While thankfully no lives have been lost and no major injuries were reported, Walmart is understandably miffed at the turn of events, leading to the litigation.

Walmart isn’t alone in their exposure to potential Tesla solar problems, so it’s worth a look to see what exactly happened with these installations, why they failed, and what we as hackers can learn from the situation. As we’ll see, it all boils down to taking electrical work very seriously and adhering to standards designed to keep everyone safe, even when they just seem like a nuisance.

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