Die Cut Machine Makes Portable Metal Cuts

July 12, 2025 by Al Williams 11 Comments

[Kevin Cheung] likes to upcycle old soda cans into — well — things. The metal is thin enough to cut by hand, but he’d started using a manual die-cutting machine, and it worked well. The problem? The machine was big and heavy, weighing well over 30 pounds. The solution was to get a lightweight die cutter. It worked better than expected, but [Kevin] really wanted it to be more portable, so he stripped it down and built the mechanism into a new case.

The video below isn’t quite a “how-to” video, but if you like watching someone handcraft something with a lot of skill, you’ll enjoy it. It also might give you ideas about how you could use one of these cutters, even if you don’t bother building a nice case for it.

We’ve seen cutters that use computer control, but they aren’t inexpensive. They will, however, make the same kind of cuts. But these manual die cutters are very inexpensive, and you simply have to find a way to make the die. You can easily make them for cutting paper, and, with the right materials, you can make the kind you see in [Kevin]’s video, too.

We have to admit, carrying the gizmo into a public place seemed to make a lot of people happy. So maybe portability is a good goal. But either way, you can have some fun with a machine like that.

If you want to cut paper, these work great. If you want paper to make the cuts, we have just the thing for you.

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The 555 Writ Large

July 12, 2025 by Al Williams 25 Comments

Few electronic ICs can claim to be as famous as the 555 timer. Maybe part of the reason is that the IC doesn’t have a specific function. It has a lot of building blocks that you can use to create timers and many other kinds of circuits. Now [Stoppi] has decided to make a 555 out of discrete components. The resulting IC, as you can see in the video below, won’t win any prizes for diminutive size. But it is fun to see all the circuitry laid bare at the macro level.

The reality is that the chip doesn’t have much inside. There’s a transistor to discharge the external capacitor, a current source, two comparators, and an RS flip flop. All the hundreds of circuits you can build with those rely on how they are wired together along with a few external components.

Even on [stoppi]’s page, you can find how to wire the device to be monostable, stable, or generate tones. You can also find circuits to do several time delays. A versatile chip now blown up as big as you are likely to ever need it.

Practical? Probably not, unless you need a 555 with some kind of custom modification. But for understanding the 555, there’s not much like it.

We’ve seen macro 555s before. It is amazing how many things you can do with a 555. Seriously.

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Kids Vs Computers: Chisanbop Remembered

July 9, 2025 by Al Williams 14 Comments

If you are a certain age, you probably remember the ads and publicity around Chisanbop — the supposed ancient art of Korean finger math. Was it Korean? Sort of. Was it faster than a calculator? Sort of. [Chris Staecker] offers a great look at Chisanbop, not just how to do it, but also how it became such a significant cultural phenomenon. Take a look at the video below. Long, but worth it.

Technically, the idea is fairly simple. Your right-hand thumb is worth 5, and each finger is worth 1. So to identify 8, you hold down your thumb and the first three digits. The left hand has the same arrangement, but everything is worth ten times the right hand, so the thumb is 50, and each digit is worth 10.

With a little work, it is easy to count and add using this method. Subtraction is just the reverse. As you might expect, multiplication is just repeated addition. But the real story here isn’t how to do Chisanbop. It is more the story of how a Korean immigrant’s system went viral decades before the advent of social media.

You can argue that this is a shortcut that hurts math understanding. Or, you could argue the reverse. However, the truth is that this was around the time the calculator became widely available. Math education would shift from focusing on getting the right answer to understanding the underlying concepts. In a world where adding ten 6-digit numbers is easy with a $5 device, being able to do it with your fingers isn’t necessarily a valuable skill.

If you enjoy unconventional math methods, you may appreciate peasant multiplication.

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Oscillator Negativity Is A Good Thing

July 8, 2025 by Al Williams 6 Comments

Many people who get analog electronics still struggle a bit to design oscillators. Even common simulators often need a trick to simulate some oscillating circuits. The Barkhausen criteria state that for stable oscillation, the loop gain must be one, and the phase shift around the feedback loop must be a multiple of 360 degrees. [All Electronics Channel] provides a thorough exploration of oscillators and, specifically, negative resistance, which is punctuated by practical measurements using a VNA. Check it out in the video below.

The video does have a little math and even mentions differential equations, but don’t worry. He points out that the universe solves the equation for you.

In an LC circuit, you can consider the losses in the circuit as a resistor. That makes sense. No component is perfect. But if you could provide a negative resistance, it would cancel out the parasitic resistance. With no loss, the inductor and capacitor will go back and forth, electrically, much like a pendulum.

So, how do you get a negative resistance? You’ll need an active device. He presents some example oscillator architectures and explains how they generate negative resistances.

Crystals are a great thing to look at with a VNA. That used to be a high-dollar piece of test gear, but not anymore.

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Reliving VHS Memories With NFC And ESPHome

July 3, 2025 by Tyler August 10 Comments

Like many of us of a certain vintage, [Dillan Stock] at The Stock Pot is nostalgic for VHS tapes. It’s not so much the fuzzy picture or the tracking issues we miss, but the physical experience the physical medium brought to movie night. To recreate that magic, [Dillan] made a Modern VHS with NFC and ESPHome.

NFC tags are contained in handsomely designed 3D printed cartridges. You can tell [Dillan] put quite a bit of thought into the industrial design of these: there’s something delightfully Atari-like about them, but they have the correct aspect ratio to hold a miniaturized movie poster as a label. They’re designed to print in two pieces (no plastic wasted on supports) and snap together without glue. The printed reader is equally well thought out, with print-in-place springs for that all important analog clunk.

Electronically, the reader is almost as simple as the cartridge: it holds the NFC reader board and an ESP32. This is very similar to NFC-based audio players we’ve featured before, but it differs in the programming. Here, the ESP32 does nothing related directly to playing media: it is simply programmed to forward the NFC tag id to ESPHome. Based on that tag ID, ESPHome can turn on the TV, cue the appropriate media from a Plex server (or elsewhere), or do… well, literally anything. It’s ESPHome; if you wanted to make this and have a cartridge to start your coffee maker, you could.

If this tickles your nostalgia bone, [Dillan] has links to all the code, 3D files and even the label templates on his site. If you’re not sold yet, check out the video below and you might just change your mind. We’ve seen hacks from The Stock Pot before, everything from a rebuilt lamp to an elegant downspout and a universal remote.

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Subpixel Rendering For Impossibly Small Terminal Text

July 2, 2025 by Tyler August 46 Comments

When it comes to text, how small is too small? The experts say a six point font is the minimum for readability, but as [James Bowman] shows us, you can get away with half of that.

The goal is to produce a 40-character display on a 24 mm x 24 mm LCD that has a resolution of 240 x 240 to show a serial terminal (or other data) on the “TermDriver2” USB-to-Serial adapter. With 24 lines, that’s a line per millimeter: very small text. Three points, to be precise, half what the experts say you need. Diving this up into 40 columns gives a character cell of six by nine pixels. Is it enough?

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Keep Track Of The Compost With LoRaWAN

June 23, 2025 by Tyler August 8 Comments

Composting doesn’t seem difficult: pile up organic matter, let it rot. In practice, however, it’s a bit more complicated– if you want that sweet, sweet soil amendment in a reasonable amount of time, and to make sure any food-born pathogens and weed seeds don’t come through, you need a “hot” compost pile. How to tell if the pile is hot? Well, you could go out there and stick your arm in like a schmuck, or you could use [Dirk-WIllem van Gulik]’s “LORAWAN Compostheap solarpowered temperaturesensor” (sic).

The project is exactly what it sounds like, once you add some spaces: a solar-powered temperature sensor that uses LoRaWAN to track temperatures inside (and outside, for comparison) the compost heap year round. Electronically it is pretty simple: a Helltech CubeCell AB01 LoraWAN module is wired up with three DS18B20 temperature sensors, a LiPo battery and a solar panel. (The AB01 has the required circuitry to charge the battery via solar power.) Continue reading “Keep Track Of The Compost With LoRaWAN” →