Start Your Semiconductor Fab With This DIY Tube Furnace

August 22, 2023 by Dan Maloney 3 Comments

Most of us are content to get our semiconductors from the usual sources, happily abstracting away the complexity locked within those little epoxy blobs. But eventually, you might get the itch to roll your own semiconductors, in which case you’ll need to start gearing up. And one of the first tools you’ll need is likely to be something like this DIY tube furnace.

For the uninitiated, [ProjectsInFlight] helpfully explains in the video below just what a tube furnace is and why you’d need one to start working with semiconductors. Perhaps unsurprisingly, a tube furnace is just a tube that gets really, really hot — like 1,200° C. In addition to the extreme heat, commercial furnaces are often set up to seal off the ends of the tube to create specific conditions within, such as an inert gas atmosphere or even a vacuum. The combination of heat and atmospheric control allows the budding fabricator to transform silicon wafers using chemical and physical processes.

[ProjectsInFlight]’s tube furnace started with a length of heat-resistant quartz glass tubing and a small tub of sodium silicate refractory cement, from the plumbing section of any home store. The tube was given a thin coat of cement and dried in a low oven before wrapping it with nichrome wire. The wrapped tube got another, thicker layer of silicate cement and an insulating wrap of alumina ceramic wool before applying power to cure everything at 1,000° C. The cured tube then went into a custom-built sheet steel enclosure with plenty of extra insulation, along with an Arduino and a solid-state relay to control the furnace. The video below concludes with testing the furnace by growing a silicon dioxide coating on a scrap of silicon wafer. This was helped along by the injection of a few whisps of water vapor while ramping the furnace temperature up, and the results are easily visible.

[ProjectsInFlight] still needs to add seals to the tube to control the atmosphere in there, an upgrade we’ll be on the lookout for. It’s already a great start, although it might take a while to catch up to our friend [Sam Zeloof].

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Hackaday Prize 2023: Over-the-Top Programmable Resistor Looks The Part And Performs

August 18, 2023 by Dan Maloney 18 Comments

Every once in a while we get wind of a project that we’re reluctant to write up for the simple reason that it looks too good to be true. Not that projects need to be messy to be authentic, mind you, but there are some that are just so finished and professional looking that it gives us a bit of pause. [Sebastian]’s programmable precision resistor is a shining example of such a project

While [Sebastian] describes this as “a glorified decade resistance box,” and technically that’s exactly right — at its heart it’s just a bunch of precision resistors being switched into networks to achieve a specific overall resistance — there’s a lot more going on here than just that. The project write-up, which has been rolling out slowly over the last month or so, has a lot of detail on different topologies that could have been used — [Sebastian] settled on a switched series network that only requires six relays per decade while also minimizing the contribution of relay contact resistance to the network. Speaking of which, there’s a detailed discussion on that subject, plus temperature compensation, power ratings, and how the various decades are linked together.

For as much that’s interesting about what’s under the hood, we’d be remiss to not spend a little time praising the exterior of this instrument. [Sebastian] appears to have spared no expense to make this look like a commercial product, from the rack-mount enclosure to the HP-esque front panel. The UI is all discrete pushbuttons and knobs with a long string of 16-segment LEDs — no fancy touch-screens here. The panel layout isn’t overly busy, and looks like it would be easy to use with some practice. We’d love to hear how the front and rear panel overlays were designed, too; maybe in a future project update.

This honestly looks like an instrument that you’d pay a princely sum to Keithley or H-P to own, at least back in the late 1990s or so. Kudos to [Sebastian] for the attention to detail here.

Hackaday Prize 2023: Universal Tensile Testing Machine

August 17, 2023 by Lewin Day 4 Comments

Material testing is important in big industry, where manufacturers must be able to trust the properties of the raw materials they’re using. The rest of us generally take a supplier’s word for it that they’re giving us what we’ve paid for. However, you could always take on material testing yourself with the Universal Tensile Testing Machine from [Xieshi Zhang].

Unlike a six-figure industrial machine, this build is much more affordable, costing on the order of $300 to build. It uses an Arduino to read a tensile strain gauge, and is capable of applying up to a kilonewton of force. To achieve this, it uses a NEMA 17 stepper motor driving a lead screw to apply tensile strain or compression to the specimen under test. The test fixture is assembled from 3D-printed components, and built on top of a piece of aluminium extrusion.

Fundamentally, it’s a smaller version of a machine most engineering undergraduates will see in a materials lab experiment. It could be highly useful for anyone wanting to experiment with 3D printed structures; it would be more than capable of testing various filaments and infill types for their tensile and compression performance. Video after the break.

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UChaser Follows You Anywhere

August 15, 2023 by Matthew Carlson 16 Comments

If you’ve been making up for lost years of travel in 2023, you might have seen a fellow traveler in the airport terminal or train station walking with their luggage happily careening behind them. [Jesse R] and [Brian Lindahl] wanted more of that. They wanted an open-source, low-cost system that could be put in anything.

The basic principle is that they will have a transmitter that sends both a radio signal and an ultrasonic pulse. The receiver receives the radio signal and uses it as a reference for the two ultrasonic sensors. The time since the radio signal is compared between the two, and a distance and direction are established.

In practice, the radio is an ESP32-S3 using ESP-NOW (which we’ve seen relatively recently on another project), a protocol from Espressif that offers low latency 250 bytes payloads. The ultrasonic transceiver is based on Sparkfun’s HC-SR04. For prototyping purposes on the receiver, they just removed the transmitter to avoid populating the airwaves, as to listen, you had to transmit. The prototype was an electric wheelbarrow that would happily follow you around the yard wherever you go.

With the concept validated, they moved to a custom ultrasonic setup with a custom buffer amp and damp transistor, all centered around 20kHz. The simulations suggested they should have been better than the HC-SR04 from Sparkfun, but the 30-foot (9 meters) range went to 10 feet (3 meters). They ultimately returned to using Sparkfun’s circuit rather than the custom amp.

We’re looking forward to seeing the project continue. There are various challenges, such as variability in the speed of sound, echos and reflections, and ultrasonic line of sight. We love the peak behind the curtain that allows us to see what decisions get made and the data that informs those decisions. All the code and PCB design files are available on GitHub under an MIT and Creative Common license, respectively. This project was submitted as part of the 2o23 Hackaday Prize.

Video after the break.

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Making Things Square In Three Dimensions

August 13, 2023 by Bryan Cockfield 32 Comments

Measure twice, cut once is excellent advice when building anything, from carpentry to metalworking. While this adage will certainly save a lot of headache, mistakes, and wasted material, it will only get you part of the way to constructing something that is true and square, whether that’s building a shelf, a piece of furniture, or an entire house. [PliskinAJ] demonstrates a few techniques to making things like this as square as possible, in all three dimensions.

The first method for squaring a workpiece is one most of us are familiar with, which is measuring the diagonals. This can be done with measuring tape or string and ensures that if the diagonals are equal lengths, the workpiece is square. That only gets it situated in two dimensions, though. To ensure it’s not saddle-shaped or twisted, a little more effort is required. [PliskinAJ] is focused more on welding so his solutions involve making sure the welding tables are perfectly flat and level. For larger workpieces it’s also not good enough to assume the floor is flat, either, and the solution here is to minimize the amount of contact it has with the surface by using something like jack stands or other adjustable supports.

There are a few other tips in this guide, including the use of strategic tack welds to act as pivot points and, of course, selecting good stock to build from in the first place, whether that’s lumber or metal. Good design is a factor as well. We’ve also featured a few other articles on accuracy and precision,

Opening A Curta — With Great Care

August 12, 2023 by Chris Lott 29 Comments

We’ve always admired Curta mechanical calculators, and would be very hesitant to dismantle one. But [Janus Cycle] did just that — and succeeded. A friend sent him a Curta Model 2 calculator that was frozen up. Just opening the case involved percussive force to remove a retaining pin, and once inside he discovered the main shaft had been slightly bent. No doubt this calculator had suffered a drop at some point in the past.

I’m sticking to the rule of doing no harm — I’d rather not be able to fix this than do something that causes more problems.

But surprisingly, he was able to get it substantially back in working order without completely taking apart all 600+ parts. Most of the issues were shafts whose lubrication had become gummy, and one carry lever was slightly bent. There is still a little more work, but soon this calculator will once again be cranking out results.

Has anyone dismantled a mechanical contraption this complicated before, for example a teletype machine? Let us know in the comments. If you want to brush up on your Curta knowledge, check out the Curta Calculator Page. We also wrote a Retrotechtacular about the Curta before. Thanks to [mister35mm] for sending in this tip.

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Inside A Cordless Soldering Station

August 12, 2023 by Al Williams 17 Comments

There was a time when soldering stations were unusual in hobby labs. These days, inexpensive stations are everywhere. [Kerry Wong] looks at the TS1C station, which is tiny and cordless. As he points out, cordless irons are not new, but modern battery technology has made them much more practical. However, this iron doesn’t actually have a battery.

The iron has a large 750 Farad supercapacitor. This has advantages and disadvantages. On the plus side, a supercapacitor charges quickly and doesn’t get weaker with each charging cycle like a conventional battery. On the minus side, the large capacitor makes the unit bulky compared to normal irons. [Kerry] notes that it is ergonomic, though, and he felt comfortable holding it. Also, the supercapacitor limits the amount of charge available while soldering.

It is somewhat of a balance, though. If you want to take the iron and climb a tower, you might be very interested in a longer running time. But if you return the unit to the base every few minutes, the fast charging of the cap will compensate for the lower capacity, and you’ll probably never notice it go flat.

The iron itself doesn’t display any data. The display is on the base, meaning the devices must be paired via Bluetooth. It also requires a PD-enabled USB-C connection, so you can’t just wire it to a battery. You can plug a power supply right into the iron if you prefer, but you still can’t use a simple power connection.

Of course, you assume it does an adequate job of soldering. We wanted to see inside! And [Kerry] didn’t disappoint. If you want to see soldering, skip to about the 10-minute marker. The teardown starts at around 16 minutes.

Honestly, for the bench, we’d probably stick with a wired iron. You don’t always want a base and a PD power supply for a portable iron. But if you absolutely hate cords, this could be a reasonable answer. We’ve seen another review of this iron that didn’t like the plastic casings. Maybe it is like Jedi and lightsabers: you should just build your own.

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