Clear PLA Diffuses LEDs

February 20, 2023 by Al Williams 11 Comments

[Chuck] often prints up interesting 3D prints. But we enjoyed his enhancement to a cheap LED Christmas tree kit. The original kit was simply a few green PCBs in the shape of a tree. Cute, but not really something a non-nerd would appreciate. What [Chuck] did, though, is printed a clear PLA overcoat for it and it came out great. You can see how great in the video below.

You might think transparent PLA would be really clear, but because of the layers, it is more translucent than transparent. For an LED diffuser, though, it works great. There are a few things to consider when printing for this purpose. First, you’d think vase mode would be perfect for this, but he found out it didn’t work well — possibly due to something in the model, which was a download from Thingiverse.

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Automating The Most Analog Of HVAC Equipment

February 20, 2023 by Bryan Cockfield 35 Comments

Burning wood, while not a perfect heating solution, has a number of advantages over more modern heating appliances. It’s a renewable resource, doesn’t add carbon to the atmosphere over geologic time scales like fossil fuels do, can be harvested locally using simple tools, and it doesn’t require any modern infrastructure to support it. That being said, wood stoves aren’t something that are very high-tech and don’t lend themselves particularly well to automation as a result, at least with the exception of this wood stove from [jotulf45v2].

While this doesn’t automate the loading or direct control of a modern pellet stove, it does help [jotulf45v2] know when the best times are for loading more wood into the stove and helps keep the stove in the right temperature range to avoid the dangerous formation of creosote on the inside of his chimney caused by low temperature burns. Two temperature sensors, one on the stovetop and the other on the stove pipe, monitor the stove exhaust temperature. They feed data to a Node-RED system running on a Raspberry Pi which automatically notifies the user by text message when certain stove temperatures are reached.

For anyone heating with wood, tools like this are indispensable to help avoid spending an otherwise unnecessary amount of time getting a fire up to temperature quickly without over-firing the stove. Modern pellet stoves have some more modern conveniences like this built in, but many of the perks of using cord wood are lost with these devices. There are plenty of other ways to heat with wood too; take a look at this custom wood boiler which serves as a hot water heater.

Low Power Challenge: Weather Station Runs For Months Thanks To E-Ink Display

February 20, 2023 by Robin Kearey 1 Comment

Having a device in your living room that shows weather information is convenient, and building one of those is a great project if you enjoy tinkering with microcontrollers and environmental sensors. It’s also a great way to learn about low-power design, as [x-labz] demonstrated with their e-ink weather station which works for no less than 60 days on a single battery charge. It has a clear display that shows the local temperature and humidity, as well as the weather forecast for the day.

The display is a 4.2″ e-paper module with a resolution of 400 x 300 pixels. It uses just 26 mW of power for a few seconds while it updates its image, and basically zero watts when showing a static picture. It’s driven by a tiny ESP32C3 processor board, which downloads the weather forecast from weatherapi.com every two hours. The indoor climate is measured by an SHT-21 temperature and humidity sensor mounted behind the display, while the outdoor data is gathered by a WiFi-connected sensor installed on [x-labz]’s balcony.

The key to achieving low power usage here is to keep the ESP32 in sleep mode as much as possible. The CPU briefly wakes up once every five minutes to read out the indoor sensor and once every fifteen minutes to gather data from outside, using the relatively power-hungry WiFi module.

To further reduce power consumption, the CPU core is driven at the lowest possible clock speed at all times: 10 MHz when reading the indoor sensor, and 80 MHz when using the WiFi connection. All of this helps ensure that just one 600 mAh lithium battery can keep everything running for those 60 days.

E-ink displays are perfect for text and simple graphics that don’t change too often, which is why they’re very popular in weather stations. With a bit of tweaking though, LCDs can also be optimized for low power.

Picking A Laser Hack Chat

February 20, 2023 by Dan Maloney 25 Comments

Join us on Wednesday, February 22 at noon Pacific for the Picking a Laser Hack Chat with Jonathan Schwartz!

You’ve got to admit that it’s a pretty cool world to live in that presents a problem like, “Which laser cutter should I buy?” It wasn’t all that long ago that decisions on laser purchases were strictly in the realm of Big Science, and the decision was driven as much by spending grant money as by the specifics of the application. If you were in need of a laser back then, chances are good you had some deep pockets, or at least access to someone else’s pockets.

Fast forward a couple of decades or so and buying a laser is an entirely different exercise. Lasers have become a commodity, and finding the right one depends entirely on your use cases. Lasers are no longer jealously guarded laboratory instruments, but workhorses on the vanguard of the desktop manufacturing revolution. They engrave, they cut, they melt — in short, they do a LOT of work. And it’s up to you to choose the right laser for the job.

To help us sort all this out and come up with a plan for figuring out the best laser for any use case, we’ve invited Jonathan Schwartz back on the Hack Chat. Jon dropped by back in March of 2021 to share his wealth of laser experience thanks to his laser-cutting business. This time around we’re going to focus — err, concentrate — oops, drill down — oh, whatever! — on the more practical aspects of buying a laser. We’ll talk about laser types, fiber lasers, applications vs. laser specs — anything you can think of. If you have questions about buying a laser, we’ll have answers!

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 22 at 12:00 PM Pacific time. If time zones have you tied up, 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.

Jet Engine Powers Tea Kettle

February 20, 2023 by Bryan Cockfield 36 Comments

While there are plenty of places around the world to get a great cup of tea, no one has quite burned it into their culture like those in the United Kingdom. While they don’t have the climate to grow the plants themselves, they at least have figured out the art of heating water extremely rapidly in purpose-built electric kettles while the rest of us wait to heat water on our stoves and microwaves. But that’s still not fast enough for some, like [Finlay Shellard], who just completed this jet-powered tea kettle.

[Finlay] took some inspiration cues and parts from another jet engine he had on hand that was powering his toaster. This is a pulse jet design, which is welded together from laser-cut pieces of sheet metal with guides welded in place to allow water to flow around the combustion chamber and exhaust. Pressurized water sits in a reservoir at the top of the engine, and when it is up to temperature, a valve allows it to flow to the engine to heat up. When it has passed the jet engine section, it passes a tea bag holder and then out of a spout at the end of the engine.

A few tests at 100 PSI had the hot tea exiting the engine in a non-linear fashion, so the pressure was reduced. The device now makes tea at incredibly fast speeds, with the only downsides being access to some sort of jet fuel, and also the need for a protective hearing device of some sort. For anyone attempting to do this themselves, take a look at this build which includes a turbocharger design for improved efficiency of the pulse jet itself.

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A man with dark skin in a red shirt and khaki shorts sits in a chair. His left leg has a prosthetic below the knee. The upper half of the prosthethic is an off white plastic socket with flecks of different off white plastic throughout hinting at the recycled nature of the plastic. The lower half is a metal tube attached to an artificial foot in black sandals.

Precious Plastic Prosthetics

February 20, 2023 by Navarre Bartz 8 Comments

Plastic waste is a major problem, but what if you could turn the world’s trash into treasure? [Yayasan Kaki Kita Sukasada (YKKS)] in Indonesia is doing this by using recycled plastic to make prosthetic legs.

Polypropylene source material is shredded and formed into a sheet which is molded into the required shape for the socket. A layer of cloth and foam is used to cushion the interface between the patient and the socket itself. Using waste plastic to make parts for the prosthetics lowers the price for patients as well as helps to keep this material out of the landfill.

What makes this project really exciting is that [YKKS] employs disabled people who develop the prosthetics and also trains patients on how to maintain and repair their prosthetics with easily sourced tools and materials. With some medical device companies abandoning their devices, this is certainly a welcome difference.

We’ve previously covered the Precious Plastic machines used to make the plastic sheets and the organization’s developments at small scale injection molding.

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A round clock with a color-coded face, with its name "Pingo" across it, together with a 3D animated mouse

Pingo Is An Analog Clock That Uses Colors Instead Of Hands

February 20, 2023 by Robin Kearey 8 Comments

The purpose of a clock is to show the time, obviously. But if you’ve followed Hackaday for some time, you’ll know there are about a million different ways of achieving this. [illusionmanager] added yet another method in his Pingo Color Clock, which, as the name suggests, uses color as the main indicator.

The clock’s face is divided into three concentric circular zones. The zone at the center shows the hours, while the outer ring indicates the minutes. Both change their color such that they match the zone in between, which always shows a complete rainbow, at the desired location. In the picture above for example, the magenta inner circle matches the rainbow at the 10 o’clock position, while the yellow outer circle matches it at 10 minutes past the hour, meaning it’s currently 10:10.

The rainbow ring is also moving however, and by adjusting its rotation through time you can get some interesting effects. [illusionmanager] programmed it in such a way that the outer ring is always yellow during the day, purple at night, and red at sunrise and sunset. The overall brightness is also adjusted to a day/night schedule.

As complex as the clock’s appearance may be, inside it’s quite a simple design. Nine concentric circular LED strips are driven by an ESP8266, which retrieves the time and sunrise information through its WiFi connection. A piece of translucent white acrylic acts as a diffuser, while a 3D-printed enclosure holds everything together.

Encoding the time using different colors of light has been done before in various different ways, and while we haven’t seen Pingo in real life, we believe it should be somewhat easier to read than most of those examples. It might actually form a nice complement to a recent analog LED ring clock.

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