Bee Motion Combines ESP32 With PIR Sensor And USB-C

There’s no shortage of ESP32 development boards out there, with many of them offering some “killer app” feature which may or may not align with whatever it is you’re trying to do. But if you’ve got a project that could benefit from the pairing of a powerful WiFi-enabled microcontroller and a passive infrared (PIR) motion sensor, the Bee Motion created by [Paul Price] is certainly worth a close look.

This breadboard compatible package combines an ESP32-S2 module with a top-mounted PIR sensor, making it a turn key solution for all sorts of motion sensing projects. In addition to the expected onboard voltage regulation, there’s also a LiPo charge controller and status LEDs for mobile or battery-backed operation.

While there’s far too many variables involved for [Paul] to give a specific runtime for the Bee Motion, he’s run some numbers and found that a 1500 mAH cell could potentially keep the board running for over a year if you’re taking advantage of the MCU’s deep sleep capabilities. When it’s time to recharge, whenever that may be, the board’s USB-C connector means you won’t be searching around for the proper cable.

Schematics and CAD files are available in the Bee Motion GitHub repo, and [Paul] is also selling assembled boards on Tindie. All you need now is to get inspired by some of the slick PIR projects we’ve covered in the past.

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Tracking Maximum Power Point For Solar Efficiency

In days of yore when solar panels weren’t dirt cheap, many people (and even large energy companies) used solar trackers to ensure their panels were always physically pointed at the sun to make sure they harvested every watt of energy possible. Since the price of panels has plummeted, though, it’s not economical to install complex machines to track the sun anymore. But all solar farms still track something else, called the Maximum Power Point (MPP), which ensures that even stationary panels are optimized for power production.

While small MPP trackers (MPPT) are available in solar charge controllers in the $200 range that are quite capable for small off-grid setups, [ASCAS] aka [TechBuilder] decided to roll out an open source version with a much lower price tag since most of the costs of these units are in R&D rather than in the actual components themselves. To that end, the methods that he uses for his MPPT are essentially the same as any commercial unit, known as synchronous buck conversion. This uses a specially configured switch-mode power supply (SMPS) in order to match the power output of the panels to the best power point for any given set of conditions extremely rapidly. It even works on many different battery configurations and chemistries, all configurable in software.

This build is incredibly extensive and goes deep into electrical theory and design choices. One design choice of note is the use of an ESP32 over an Arduino due to the higher resolution available when doing analog to digital conversion. There’s even a lengthy lecture on inductor core designs, and of course everything on this project is open source. We have also seen the ESP32 put to work with MPPT before, although in a slightly less refined but still intriguing way.

Thanks to [Sofia] for the tip!

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Let The Solar Free

Anyone tackling solar power for the first time will quickly find there’s a truly dizzying amount of information to understand and digest. You might think you just need to buy some solar panels, wire them together, and just sort of plug them in. But there are a hundred and one different questions about how they’ll be connected, the voltage of the panels, and the hardware for driving a load. [Michel], [case06], and [Martin Jäger] have set out to create a simpler and easier to understand charge controller named LibreSolar.

a diagram showing how the libre solar is wired up

A charge controller is fundamentally a simple idea. The goal is to charge a battery with solar panels, which means it’s essentially just a heavy-duty DC/DC buck converter. What makes this project different is that it is an open platform built for extensibility.

There are UEXT connectors included for adding extra peripherals, and with some tweaks to the STM32 firmware, it would be easy to handle small wind turbines (with some rectification to convert to DC, of course). LibreSolar seems to be designed with an eye towards creating a nano-scale localized networked grid. For example, they’ve developed a Raspberry Pi Zero module that uses WiFi to create a CAN bus allowing the boxes to communicate their maximum voltage to each other. This makes the system as plug-and-play as possible, as the bus doesn’t require a master controller to communicate.

With features such as MPPT (Maximum Power Point Tracking), 20 amp peak charging, a USB interface for updating, and several built-in protection mechanisms, it’s clearly a well thought through project. We look forward to seeing it deployed in the real world!

Improved Outdoor Solar Harvester Now Handles All The Parts

[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.

Soak Up The Sun With This 3D Printed Solar Harvester

At first glance, adding solar power to your project might seem easy. Get a photovoltaic panel, point it towards the big ball of burning gas in the sky, and off you go. But in reality, there’s a bit more to it than that. Especially when you’re trying to do something on a small scale. Without a rooftop full of panels pumping out power, you’ve got to take what you can get.

If you’re looking to power small electronic devices such as sensors with a single solar panel, [Vadim Panov] has put together a very concise write-up and video on building a low-cost solar harvester. It combines a relatively small photovoltaic panel, a charging circuit, and a battery for energy storage into a easily mountable package. He’s provided all the details necessary to create your own version, all you have to do now is come up with the application for it.

As far as the electronics go, this project is about as straightforward as it gets. The three watt panel is connected up to a simplistic charging circuit, which in turn feeds into a single 18650 cell. You might be wondering why a charge controller is even necessary in such a simple set up. One problem is that the output voltage of the panel is higher than that of the battery. You also need a blocking diode that will prevent the battery from discharging into the cell during the night or in cloudy conditions.

While the electronics might seem elementary to some readers, we think the 3D printed case alone is worth taking a look at. Not only has [Vadim] come up with a design that perfectly encloses the fragile solar panel and associated electronics, but in the video after the break, he also explains how the entire thing can be made waterproof with an epoxy coating. As 3D prints can have a tendency to be porous, this technique is definitely something you should file away mentally if you’ve been thinking of deploying a printed enclosure outdoors.

Whether you’re looking to power environmental sensors for as near a century as is technically possible or a portable OpenWRT router for mobile anonymity, these small solar panels hold a lot of promise if you know how to work around their limitations.

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Keeping Birds At Bay With An Automated Spinning Owl

There’s nothing wrong with building something just to build it, but there’s something especially satisfying about being able to solve a real-world problem with a piece of gear you’ve designed and fabricated. When all the traditional methods to keep birds from roosting on his mother’s property failed, [MNMakerMan] decided to come up with a more persuasive option: a solar powered spinning owl complete with expandable batons.

We imagine the owl isn’t strictly necessary when you’re whacking the birds with a metal bar to begin with, but it does add a nice touch. Perhaps it will even serve to deter some of the less adventurous birds before they get within clobbering distance, which is probably in their best interest. [MNMakerMan] says the rotation speed of the bars seems low enough that he doesn’t think it will do the birds any physical harm, but it’s still got to be fairly unpleasant.

At first glance you might think that this contraption simply spins when the small 10 watt photovoltaic panel next to it catches the sun, but there’s actually a bit more to it than that. Sure he probably could just have it spin constantly whenever the sun is up, but instead [MNMakerMan] is using a ATtiny85 to control the 11 RPM geared DC motor with a IRF540 MOSFET. By adding a DS3231 RTC module into the mix, he’s able to not only accurately control when the spinner begins and ends its bird-busting shift, but implement timed patterns rather than running it the whole time. All of which can of course be fine-tuned by adjusting a couple variables and reflashing the chip.

We’ve seen plenty of automated systems for keeping cats away, and of course squirrels are a common target for such builds as well, but devices to deter birds are considerably less common among these pages. So it would seem that, at least for now, [MNMakerMan] has the market cornered on solar bird smashing gadgets. We’re sure Mom’s very proud.

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Solar Heart Engineered To Beat For Decades

It’s often said that if something is worth doing it’s worth doing right, or maybe even worth overdoing. This is clearly a concept that [ANTALIFE] takes very seriously, as made abundantly clear by projects like the solar powered “beating” heart he made as a gift for his wife. What for most of us would have ended up being a junk bin build becomes a considerable engineering project in his hands, with a level of research and fine tuning that’s frankly staggering.

But [ANTALIFE] didn’t put this much thought into the device just for fun. He wants it to remain functional for as long as 30 years, and hopes he and the missus can still look on it fondly in their retirement years. Keeping an electronic device up and running for decades straight means you need to look carefully at each component and try to steer clear of any potential pitfalls.

The biggest one was the battery. More specifically, the fact he couldn’t use one. The lifetime of most rechargeable batteries is measured in hundreds of cycles, which for a device which will be charged by solar every day, means the battery is going to start showing its age in only 4 to 5 years. That simply wasn’t going to cut it.

[ANTALIFE] did some digging and realized that the solution was to use a supercapacitor, specifically the AVX SCMS22C255PRBA0. This is little wonder is rated for a staggering half million cycles, which in theory means that even with daily use it should still take a charge in the year 3300. In practice of course there are a lot of variables which will reduce that lifetime such as temperature fluctuations and the Earth being conquered by apes; but no matter what caveats you put on the figure it should still make 30 years without breaking a sweat.

Similar thought was given to choosing a solar cell with a suitably long lifetime, and he did plenty of testing and experimentation with his charging circuit, including some very nice graphs showing efficiency over time, to make sure it was up to snuff. Finally he walks the reader though his light-sensitive ring oscillator circuit which gives the device its pleasing “breathing” effect once the lights go down.

We’d love to bring you an update on this device in 30 years to see how close [ANTALIFE] got, but as we’re still trying to work the kinks out of the mobile version of the site we can’t make any guarantees about what the direct-brain interface version of HaD might look like. In the meantime though, you can read up on the long term battle between supercapacitors and traditional batteries.

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