Ask Hackaday: What’s The Best Way To Heat A Tent With A Laptop?

For Europeans, August is usually a month of blistering heatwaves, day after day of cloudless skies and burning sun that ripens fruit and turns we locals a variety of shades of pink. Hacker camps during this month are lazy days of cool projects and hot nights of lasers, Club-Mate, and techno music, with tents being warm enough under the night sky to dispense with a sleeping bag altogether.

Sometimes though, the whims of the global weather patterns smile less upon us hackers, and our balmy summer break becomes a little more frigid. At BornHack 2021 for example we packed for a heatwave and were met with a Denmark under the grip of the Northern air mass. How’s a hacker to keep warm?

Continue reading “Ask Hackaday: What’s The Best Way To Heat A Tent With A Laptop?”

Keep Coffee Warm Through Induction Heating

Transformers have an obvious use for increasing or decreasing the voltage in AC systems, but they have many other esoteric uses as well. Electric motors and generators are functionally similar and can be modeled as if they are transformers, but the truly interesting applications are outside these industrial settings. Wireless charging is essentially an air-core transformer that allows power to flow through otherwise empty space, and induction cooking uses a similar principle to induce current flow in pots and pans. And, in this case, coffee mugs.

[Sajjad]’s project is an effort to keep his coffee warm while it sits on his desk. To build this special transformer he places his mug inside a coil of thick wire which is connected to a square wave generator. A capacitor sits in parallel with the coil of wire which allows the device to achieve resonance at a specific tuned frequency. Once at that frequency, the coil of wire efficiently generates eddy currents in the metal part of the coffee mug and heats the coffee with a minimum of input energy.

While this project doesn’t work for ceramic mugs, [Sajjad] does demonstrate it with a metal spoon in the mug. While it doesn’t heat up to levels high enough to melt solder, it works to keep coffee warm in a pinch if a metal mug isn’t available. He also plans to upgrade it so it takes up slightly less space on his desk. For now, though, it can easily keep his mug of coffee hot while it sits on his test bench.

Continue reading “Keep Coffee Warm Through Induction Heating”

Off-The-Shelf Parts Make A Tidy Heater For Resin Printer

Resin printers can offer excellent surface finish and higher detail than other 3D printing technologies, but they come with their own set of drawbacks. One is that they’re quite sensitive to temperature, generally requiring the resin chamber to be heated to 25-30 degrees Celsius for good performance. To help maintain a stable temperature without a lot of mucking around, [Grant] put together a simple chamber heater for his printer at home.

Rather than go for a custom build from scratch with a microcontroller, [Grant] was well aware that off-the-shelf solutions could easily do the job. Thus, a W1209 temperature control board was selected, available for under $5 online. Hooked up to a thermocouple, it can switch heating elements via its onboard relay to maintain the set temperature desired. In this case, [Grant] chose a set of positive-temperature coefficient heating elements to do the job, installing them around the resin chamber for efficiency.

The heater can preheat the chamber in under fifteen minutes, much quicker than other solutions using space heaters or heat mats. The time savings will be much appreciated by [Grant], we’re sure, along with the attendant increase in print quality.  If you’re still not sure if resin printing is for you, have a read of our primer. And, if you’ve got your own workflow improvements for resin printing, drop us a line!

Teardown: Go Warmer USB Rechargeable Hand Heater

Under normal circumstances, if an electronic gadget in your pocket suddenly became hot to the touch, it would be cause for alarm. But not so with the Go Warmer. This lozenge shaped device is not only a USB power bank that can keep your mobile devices topped up, but is also doubles as a miniature heater that the manufacturer claims can bring its surface temperature up to 48 °C (120 °F) for several hours. You can hold in in your hand, put it in your pocket, maybe even sit on it if you’re particularly daring. The possibilities are endless, at least until the 4,000 mAh battery runs down.

For $14.99 USD, the Go Warmer certainly isn’t much of a deal when compared to other battery packs. Even if it does come with a swanky velveteen carrying pouch. But is it a good deal for one that can heat itself up without exploding? Let’s crack this metallic egg and find out.

Continue reading “Teardown: Go Warmer USB Rechargeable Hand Heater”

Heater Joins The Internet Of Things With ESP32 Board

The wood-burning heater [g3gg0] has at home works perfectly, except for one flaw: the pellet reservoir needs to be manually refilled every few days. Humans being notoriously unreliable creatures, this critical task is sometimes overlooked, which naturally leads to literally chilling results.

With automatic fill systems expensive and difficult to install, [g3gg0] wanted to find some kind of way for the heater to notify its caretakers about any potential fault conditions. Not just the fact that it was out of fuel (though that would naturally be the most common alert), but any other issue which would potentially keep the heater from doing it’s job. In short, the heater was going to get a one-way ticket to the Internet of Things.

As it turns out, this task was not quite as difficult as you might expect. The Windhager heater already had upgrade bays where the user could insert additional modules and sensors, as well as a rudimentary data bus over RS-485. All [g3gg0] had to do was tap into this bus, decode what the packets contained, and use the information to generate alerts over the network. The ESP32 was more than up to the task, it just needed a custom PCB and 3D printed enclosure that would allow it to slot into the heater like an official expansion module.

When an interesting message flashes across the bus, the ESP32 captures it and relays the appropriate message to an MQTT broker. From there, the automation possibilities are nearly endless. In this case, the heater’s status information is being visualized with tools like Grafana, and important alerts are sent out to mobile devices with PushingBox. With a setup like this, the Windhager will never go hungry again.

Continue reading “Heater Joins The Internet Of Things With ESP32 Board”

Retrotechtacular: The Nernst Lamp

After dominating the illumination market for more than a century, it’s easy to think of the glowing filament of the standard incandescent lamp as the only way people found to turn electricity into light. But plenty of fertile minds turned out alternative designs, one of which is the fascinating Nernst lamp, which we’d previously never heard of.

If the name sounds familiar, it’s likely through exposure to [Walther Nernst]’s equation for electrochemistry, or for his “New Heat Theorem” which eventually became the Third Law of Thermodynamics. Pal of [Einstein] and eventual Nobel laureate, [Nernst] was also a bit of a tinkerer, and he came up with a design for an incandescent lamp in 1897 that was twice as efficient as carbon-filament lamps. The video below, from the Edison Tech Center, details the design, which used a ceramic “glower rod” that would incandesce when current flowed through it. The glower, though, was not conductive until it was quite hot, so separate heater coils that gave the glower a start on the process were included; these were switched off by a relay built into the base of the lamp once the glower started conducting.

It’s a complicated design, but its efficiency, coupled with a better light spectrum and the fact that it didn’t need a vacuum bulb since the glower wouldn’t oxidize like a carbon or tungsten filament, gave it certain advantages that let it stake out a decent share of the early market for electric illumination. It was even the light source for one of the first facsimile machines. We find it a very clever use of what were at the time exotic materials, and wonder if this could have lead to something like vacuum tubes without the vacuum.

Continue reading “Retrotechtacular: The Nernst Lamp”

Thermochromic Display Tells You The Temperature Despite Your Current Mood

Readers who survived the 1970s will no doubt remember the “mood ring” fad, where a liquid crystal mounted to a ring would magically reveal your current emotional state to all and sundry by changing color. This nifty thermochromic display is based on the same principle, and while it might not start a new craze, it’s still pretty mesmerizing to watch.

This isn’t [Moritz v. Sivers]’ first attempt at a thermochromic display. His earlier version was far more complicated, using separate copper plates clad with thermochromic film for each segment, with Peltier devices to cool and heat them individually. Version two is much simpler, using a printed circuit board with heating elements in the shape of seven-segment displays etched into it. The thermochromic film sits directly on the heater PCB; a control PCB below has the MCU and sensors on it. The display alternates between temperature and humidity, with the segments fading in an uneven and ghostly way that really makes this fun to watch. [Moritz] has made the build files available, and there’s a detailed Instructable as well.

We’re always on the lookout for alternate display modalities, especially when they look this cool. We’ve seen other thermochromic displays before, of course, and persistence of phosphorescence looks great, too.

Continue reading “Thermochromic Display Tells You The Temperature Despite Your Current Mood”