A circuit board with a memory chip in a socket, and many memory chips in foam

Simple DRAM Tester Built With Spare Parts

Some of the most popular vintage computers are now more than forty years old, and their memory just ain’t how it used to be. Identifying bad memory chips can quickly become a chore, so [Jan Beta] spent some time putting together a cheap DRAM tester out of spare parts.

This little tester can be used with 4164 and 41256 DRAM memory chips. 4164 DRAM was used in several popular home computers throughout the 1970s and 1980s, including the Apple ][ series, Commodore 64, ZX Spectrum and many more. Likewise, the 41256 was used in the Commodore Amiga. These computers are incredibly popular in the vintage computing community, and its not uncommon to find bad memory in any of them.

With an Arduino at its core, this DRAM tester uses the most basic of electronic components, and any modest tinkerer should have pretty much everything in stock. The original project can be found here, including the Arduino code. Just pop the suspect chip into the ZIF socket, hit the reset switch, and wait for the LED – green is good, and red means it’s toast.

It’s a great sanity check for when you’re neck deep in suspect DRAM. A failed test is a sure sign that the chip is bad, however the tester does occasionally report a false pass. Not every issue can be identified with such a simple tester, however it’s great at weeding out the chips that are definitely dead.

If you’re not short on cash, then the Chip Tester Pro may be more to your liking, however it’s hard to beat the simplicity and thriftiness of building your own simple tester from spare parts. If you’re a little more adventurous, this in-circuit debugger could come in handy.

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Neon, Ukraine, And The Global Semiconductor Industry

On our news feeds and TV channels at the moment are many stories concerning the war in Ukraine, and among them is one which may have an effect on the high-tech industries. It seems that a significant percentage of the world’s neon gas is produced in Ukrainian factories, and there is concern among pundits and electronics manufacturers that a disruption of this supply could be a further problem for an industry already reeling from the COVID-related chip shortage. It’s thus worth taking a quick look at the neon business from an engineering perspective to perhaps make sense of some of those concerns.

As most readers will know from their high school chemistry lessons, neon is one of the so-called inert gasses, sitting in the column at the extreme right of the Periodic table. It occurs in nature as a small percentage of the air we breathe and is extracted from the air by fractional distillation of the liquid phase. The important point from the above sentences is that the same neon is all around us in the air as there is in Ukraine, in other words, there is no strategic neon mine in the Ukrainian countryside about to be overrun by the Russian invaders.

So why do we source so much neon from Ukraine, if we’re constantly breathing the stuff in and out everywhere else in the world? Since the air separation industry is alive and well worldwide for the production of liquid nitrogen and oxygen as well as the slightly more numerous inert gasses, we’re guessing that the answer lies in economics. It’s a bit harder to extract neon from air than it is argon because there is less of it in the air. Since it can be brought for a reasonable cost from the Ukrainians who have made it their business to extract it, there is little benefit in American or Western European companies trying to compete. Our take is that if the supply of Ukrainian neon is interrupted there may be a short period of neon scarcity. After that, air extraction companies will quite speedily install whatever extra plant they need in order to service the demand. If that’s your area of expertise, we’d love to hear from you in the comments.

Here at Hackaday we are saddened beyond words at what has happened in Ukraine, and we hope our Ukrainian readers and those Ukrainian hackers whose work we’ve featured make it through safely. We sincerely hope that this madness can be ended and that we can mention the country in the context of cool hacks again rather than war.

If you are interested in the strategic value of inert gasses, have a read about the global helium supply.

Header image: Lestat (Jan Mehlich), CC BY-SA 3.0.

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Hackaday Links: February 27, 2022

If there’s one thing that can trigger people, it’s the printer racket. Printer manufacturers who put DRM-like features into their consumables are rightly viewed as Satan’s spawn, and while these monsters have been content so far to only put digital rights management features into their ink and toner cartridges, they appear to now have their rapacious gaze set on print media too. At least according to the good folks over at the Electronic Frontier Foundation, who claim that Dymo’s latest generation of label printers will have RFID tags in the label cartridges, apparently to prevent consumers from buying non-Dymo media. The company doesn’t bill it as a way to lock you into their exorbitantly priced consumables, of course; rather, this is an exciting new feature that’s called “Automatic Label Recognition,” which keeps track of what labels are installed and how many are left. Of course, this is just red meat to people like us, and we fully expect to see workarounds in the not-to-distant future.

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ESP32 Virtual Machine Lets You Change Programs On The Fly

Often, reprogramming a microcontroller involves placing it in reset, flashing the code, and letting it fire back up. It usually involves shutting the chip down entirely. However, [bor0] has built a virtual machine that runs on the ESP32, allowing for dynamic program updates to happen.

The code is inspired by the CHIP-8, a relatively ancient interpreter that had some gaming applications. [bor0] had already created a VM simulating the CHIP-8, and repurposed it here, taking out the gaming-related drawing instructions and replacing them with those that control IO pins. Registers have also been changed to 16 bits for added flexibility and headroom.

It’s probably not something with immediate ground-breaking applications for most people, but it’s a different way of working with and programming the ESP32, and that’s pretty neat.

The ESP32 is a powerful chip, too, as we all know – and it makes a great 8-bit emulator to boot. Sound off in the comments with your thoughts on what would make a killer application for the ESP32 VM!

[Thanks to satancete for the tip!]

Two clothespin hacks mentioned in the article, side-by-side.

Need To Probe Circuits? Remember About Clothespins!

After browsing Thingiverse for some printable PCB probe designs, [Henry York] looked around and found a wooden clothespin on his desk. After some collaboration between his 3D printer and his CNC, Henry graced us with a nifty helper tool design that many of us might want to make in a pinch – a small, cheap and easy to make PCB probe, for circuits where soldering and headers are out of the question. Small magnets are glued to the clothespin, holding it flush to a magnetizable work surface (aka a toaster tray), and the probing itself is done by an extruder cleaning needle end. 3D printer and Edge.Cuts files are shared with us – thanks to Henry’s helpfulness, it should be easy to repeat if ever needed!

[Tyler Rosonke] (@zonksec) was programming a batch of badges and needed a reliable way to attach to a 6-pin ISP header – without actually soldering to the badges before they’re handed out to participants! A clothespin materialized nearby yet again – most likely, channeled from a different dimension by the spirit of numerous acrylic-cast pogopin-toothed clip-on tools we scroll by on Aliexpress. With a small perfboard piece and a bunch of pogopins jumping out of their respective drawers, it became no longer necessary to hold a bundle of male-ended pin header wires at a weird angle while nervously looking at the avrdude progress bar. This ended up saving a whole lot of time, something that’s always best spent on adding insidious bugs to the badge firmware (as well as, perhaps, easter eggs).

We’d love to hear about all the small hacks and improvements that you, hackers in our audience, invent. Whether it’s reusing a SOIC flashing clip for ISP programming or printing yourself an octopus-like contraption with needle probes, you should share it with us!

Image showing differences between WS2815 and WS2813 LED strips - the WS2815 strip lighting is more uniform throughout the strip's length.

Teaching You Everything You Might Have Missed About Addressable LEDs

Often, financial motivation results in people writing great educational material for hackers. Such is absolutely the case with this extensive documentation blog post on addressable LEDs by [DeRun]. This article could very be named “Addressable LEDs 101”, and it’s a must-scroll-through for anyone, whether you’re a seasoned hacker, or an artist with hardly any technical background and a desire to put LEDs in your creations.

This blog post is easy to read, painting a complete picture of what you can expect from different addressable LED types, and with apt illustrations to boot. Ever wonder which one of the addressable strips you should get from your retailer of choice, and what are the limitations of any specific type? Or, perhaps, you’d like to know – why is it that a strip with a certain LED controller is suspiciously cheap or expensive? You’re more than welcome to, at least, scroll through and fill into any of your addressable LED knowledge gaps, whether it’s voltage drops, color accuracy differences, data transfer protocol basics or dead LED failsafes.

Addressable LEDs have a special place in our hearts, it’s as if the sun started shining brighter after we’ve discovered them… or, perhaps, it’s all the LEDs we are now able to use. WS2812 is a staple of the addressable LED world, which is why we see them even be targets of both clone manufacturers and patent trolls. However, just like the blog post we highlight today mentions, there’s plenty of other options. Either way do keep coming cover a new addressable LED-related hack, like rewriting their drivers to optimize them, or adding 3.3V compatibility with just a diode.

We thank [Helge] for sharing this with us!

S15351 tube transmitter

Retro And New Tech Combine In This Hybrid Ham Transmitter

We’ve said it before and we’ll say it again: the best part about holding an amateur radio license is that it lets you build and use your own transmitting equipment. Hams have been doing this for more than a century — indeed, it was once the only way to get on the air — using whatever technology was available. But the mix of technologies in this low-power transmitter for the 80-meter band is something you don’t see every day.

As ham [Helge Fykse (LA6NCA)] describes in the video below, the project began when he came into possession of a bonanza of vacuum tubes — 12A6 tetrodes, specifically. The new-old-stock tubes were perfect for an RF power amplifier, but that left the problem of what to use for an oscillator. [Helge] chose to meld the old with the new and used oscillator board that he designed. The board has an ATmega88 microcontroller and an Si5351 oscillator, along with a 3V3 regulator to let the module run on 12 volts. And for a nice retro touch, [Helge] put the board in a 3D printed case that looks like an old-fashioned quartz crystal.

There are some other nice design touches here too. A low-pass filter cleans up the harmonics of the oscillator’s 3.5-MHz square wave output before feeding it to the amplifier, in a nod to proper spectrum hygiene. The primary for the amp’s air-core output transformer is hand-wound, with 3D printed spacers to keep the winding neat and even. The tuning process shown below is interesting, and the transmitter was used to make a solid contact with another ham about 100 km away. And we really liked the look of [Helge]’s shack, stuffed as it is with gear both old and new.

We’ve personally tried the Si5351 for QRP transmitters before, but this blend of the old and new really makes us want to find some tubes and get to playing.

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