MOSFET Heater Is Its Own Thermostat

March 29, 2023 by Bryan Cockfield 16 Comments

While we might all be quick to grab a microcontroller and an appropriate sensor to solve some problem, gather data about a system, or control another piece of technology, there are some downsides with this method. Software has a lot of failure modes, and relying on it without any backups or redundancy can lead to problems. Often, a much more reliable way to solve a simple problem is with hardware. This heating circuit, for example, uses a MOSFET as a heating element and as its own temperature control.

The function of the circuit relies on a parasitic diode formed within the transistor itself, inherent in its construction. This diode is found in most power MOSFETs and conducts from the source to the drain. The key is that it conducts at a rate proportional to its temperature, so if the circuit is fed with AC, during the negative half of the voltage cycle this diode can be probed and used as a thermostat. In this build, it is controlled by a set of resistors attached to a voltage regulator, which turn the heater on if it hasn’t reached its threshold temperature yet.

In theory, these resistors could be replaced with potentiometers to allow for adjustable heat for certain applications, with plastic cutting and welding, temperature control for small biological systems, or heating other circuits as target applications for this type of analog circuitry. For more analog circuit design inspiration, though, you’ll want to take a look at some classic pieces of electronics literature.

Robot 3D Prints Giant Metal Parts With Induction Heat

March 29, 2023 by Bryan Cockfield 36 Comments

While our desktop machines are largely limited to various types of plastic, 3D printing in other materials offers unique benefits. For example, printing with concrete makes it possible to quickly build houses, and we’ve even seen things like sugar laid down layer by layer into edible prints. Metals are often challenging to print with due to its high melting temperatures, though, and while this has often been solved with lasers a new method uses induction heating to deposit the metals instead.

A company in Arizona called Rosotics has developed a large-scale printer based on this this method that they’re calling the Mantis. It uses three robotic arms to lay down metal prints of remarkable size, around eight meters wide and six meters tall. It can churn through about 50 kg of metal per hour, and can be run off of a standard 240 V outlet. The company is focusing on aerospace applications, with rendered rocket components that remind us of what Relativity Space is working on.

Nothing inspires confidence like a low-quality render.

The induction heating method for the feedstock not only means they can avoid using power-hungry and complex lasers to sinter powdered metal, a material expensive in its own right, but they can use more common metal wire feedstock instead. In addition to being cheaper and easier to work with, wire is also safer. Rosotics points out that some materials used in traditional laser sintering, such as powdered titanium, are actually explosive.

Of course, the elephant in the room is that Relativity recently launched a 33 meter (110 foot) tall 3D printed rocket over the Kármán line — while Rosotics hasn’t even provided a picture of what a component printed with their technology looks like. Rather than being open about their position in the market, the quotes from CEO Christian LaRosa make it seem like he’s blissfully unaware his fledgling company is already on the back foot.

If you’ve got some rocket propellant tanks you’d like printed, the company says they’ll start taking orders in October. Though you’ll need to come up with a $95,000 deposit before they’ll start the work. If you’re looking for something a little more affordable, it’s possible to convert a MIG welder into a rudimentary metal 3D printer instead.

Magic 8 Ball Provides Tech Support

March 28, 2023 by Bryan Cockfield 15 Comments

ChatGPT might be making the news these days for being able to answer basically any question it’s asked, those of us who are a little older remember a much simpler technology that did about the same thing. The humble “Magic 8 Ball” could take nearly the same inputs, provided they were parsed in simple yes/no form, and provide marginal help similar to the AI tools of today. For a toy with no battery or screen, this was quite an accomplishment. But the small toy couldn’t give specific technical support help, so [kodi] made one that can.

The new 8 Ball foregoes the central fluid-filled chamber for an STM32 Blue Pill board with a few lithium batteries to power it. The original plastic shell was split in two with a hacksaw and fitted with a 3D printed ring which allows the two halves to be reconnected and separated again when it needs to charge. It uses a circular OLED to display the various messages of tech support, which are displayed when an accelerometer detects that the toy has been shaken.

Granted, most of the messages are about as helpful to solving a tech support issue as the original magic 8 Ball’s would have been, but we appreciate the ingenuity and carefree nature of a project like this. It also did an excellent job at operating in a low-power state as well, to avoid needing to charge it often. There have been a few other digital conversions of these analog fortune tellers as well, like this one which adds GIFs to each of the original answers.

Hams Watch For Meteors

March 28, 2023 by Bryan Cockfield 13 Comments

After passing an exam and obtaining a license, an amateur radio operator will typically pick up a VHF ratio and start talking to other hams in their local community. From there a whole array of paths open up, and some will focus on interesting ways of bouncing signals around the atmosphere. There are all kinds of ways of propagating radio waves and bouncing them off of various reflective objects, such as the Moon, various layers of the ionosphere, or even the auroras, but none are quite as fleeting as bouncing a signal off of a meteor that’s just burned up in the atmosphere.

While they aren’t specifically focused on communicating via meteor bounce, The UK Meteor Beacon Project hopes to leverage amateur radio operators and amateur radio astronomers to research more about meteors as they interact with the atmosphere. A large radio beacon, which has already been placed into service, broadcasts a circularly-polarized signal in the six-meter band which is easily reflected back to Earth off of meteors. Specialized receivers can pick up these signals, and are coordinated among a network of other receivers which stream the data they recover over the internet back to a central server.

With this information, the project can determine where the meteor came from, some of the properties of the meteors, and compute their trajectories by listening for the radio echoes the meteors produce. While this is still in the beginning phases and information is relatively scarce, the receivers seem to be able to be built around RTL-SDR modules that we have seen be useful across a wide variety of radio projects for an absolute minimum of cost.

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An Old Netbook Spills Its Secrets

March 27, 2023 by Bryan Cockfield 35 Comments

For a brief moment in the late ’00s, netbooks dominated the low-cost mobile computing market. These were small, low-cost, low-power laptops, some tiny enough to only have a seven-inch display, and usually with extremely limiting hardware even for the time. There aren’t very many reasons to own a machine of this era today, since even the cheapest of tablets or Chromebooks are typically far more capable than the Atom-based devices from over a decade ago. There is one set of these netbooks from that time with a secret up its sleeve, though: Phoenix Hyperspace.

Hyperspace was envisioned as a way for these slow, low-power computers to instantly boot or switch between operating systems. [cathoderaydude] wanted to figure out what made this piece of software tick, so he grabbed one of the only netbooks that it was ever installed on, a Samsung N210. The machine has both Windows 7 and a custom Linux distribution installed on it, and with Hyperspace it’s possible to switch almost seamlessly between them in about six seconds; effectively instantly for the time. Continue reading “An Old Netbook Spills Its Secrets” →

Long-Distance Gaming Over Packet Radio

March 27, 2023 by Bryan Cockfield 25 Comments

The amateur radio community often gets stereotyped as a hobby with a minimum age requirement around 70, gatekeeping airwaves from those with less experience or simply ignoring unfamiliar beginners. While there is a small amount of truth to this on some local repeaters or specific frequencies, the spectrum is big enough to easily ignore those types and explore the hobby without worry (provided you are properly licensed). One of the best examples of this we’ve seen recently of esoteric radio use is this method of using packet radio to play a game of Colossal Cave Adventure.

Packet radio is a method by which digital information can be sent out over the air to nodes, which are programmed to receive these transmissions and act on them. Typically this involves something like email or SMS messaging, so playing a text-based game over the air is not too much different than its intended use. For this build, [GlassTTY] aka [G6AML] is using a Kenwood TH-D72 which receives the packets from a Mac computer. It broadcasts these packets to his node, which receives these packets and sends them to a PDP-11 running the game. Information is then sent back to the Kenwood and attached Mac in much the same way as a standard Internet connection.

The unique features of packet radio make it both an interesting and useful niche within the ham radio community, allowing for all kinds of uses where data transmission might otherwise be infeasible or impossible. A common use case is APRS, which is often used on VHF bands to send weather and position information out, but there are plenty of other uses for it as well.

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How Much Programming Can ChatGPT Really Do?

March 25, 2023 by Bryan Cockfield 50 Comments

By now we’ve all seen articles where the entire copy has been written by ChatGPT. It’s essentially a trope of its own at this point, so we will start out by assuring you that this article is being written by a human. AI tools do seem poised to be extremely disruptive to certain industries, though, but this doesn’t necessarily have to be a bad thing as long as they continue to be viewed as tools, rather than direct replacements. ChatGPT can be used to assist in plenty of tasks, and can help augment processes like programming (rather than becoming the programmer itself), and this article shows a few examples of what it might be used for.

AI comments are better than nothing…probably.

While it can write some programs on its own, in some cases quite capably, for specialized or complex tasks it might not be quite up to the challenge yet. It will often appear extremely confident in its solutions even if it’s providing poor or false information, though, but that doesn’t mean it can’t or shouldn’t be used at all.

The article goes over a few of the ways it can function more as an assistant than a programmer, including generating filler content for something like an SQL database, converting data from one format to another, converting programs from one language to another, and even help with a program’s debugging process.

Some other things that ChatGPT can be used for that we’ve been able to come up with include asking for recommendations for libraries we didn’t know existed, as well as asking for music recommendations to play in the background while working. Tools like these are extremely impressive, and while they likely aren’t taking over anyone’s job right now, that might not always be the case.