Mostly Non-Volatile Memory With Supercapacitors

Back in the days of old, computers used EPROMs to store their most vital data – usually character maps and a BASIC interpreter. The nature of these EPROMs meant you could write to them easily enough, but erasing them meant putting them under an ultraviolet light. Times have changed and now we have EEPROMs, which can be erased electronically, and Flash, the latest and greatest technology that would by any other name be called an EEPROM. [Nicholas] wanted an alternative to these 27xx-series EPROMs, and found his answer in supercapacitors.

[Nick]’s creation is a mostly non-volatile memory built around an old 62256 32k SRAM. SRAM is completely unlike EPROMs or Flash, in that it requires power to keep all its bits in memory. Capacitor technology has improved dramatically since the 1980s, and by using a supercap and one of these RAM chips, [Nick] has created a substitute for a 27-series EPROM that keeps all its memory alive for days at a time.

The circuit requires a small bit of electronics tucked between the EPROM socket and the SRAM chip; just enough to turn the 12 Volts coming from the EPROM programming pin to the 5 Volts expected from the SRAM’s Write Enable pin. This is accomplished by a few LEDs in series, and a 0.1F 5.5V supercap which keeps the SRAM alive when the power is off.

As for why anyone would want to do this when modern technologies like Flash can be found, we can think of two reasons. For strange EPROM sizes, old SRAMs abound, but a suitable Flash chip in the right package (and the right voltage) might be very hard to find. Also, EEPROMs have a write lifetime; SRAMs can be written to an infinite number of times. It’s not the best solution in every case, but it is certainly interesting, and could be useful for more than a few vintage computing enthusiasts.

This project makes us think of another where an LED may have been supplying keep-alive power to some volatile memory.

TEMPEST: a Tin Foil Hat for Your Electronics and Their Secrets

Electronics leak waves and if you know what you’re doing you can steal people’s data using this phenomenon. How thick is your tinfoil hat? And you sure it’s thick enough? Well, it turns out that there’s a (secret) government standard for all of this: TEMPEST. Yes, all-caps. No, it’s not an acronym. It’s a secret codename, and codenames are more fun WHEN SHOUTED OUT LOUD!

The TEMPEST idea in a nutshell is that electronic devices leak electromagnetic waves when they do things like switch bits from ones to zeros or move electron beams around to make images on CRT screens. If an adversary can remotely listen in to these unintentional broadcasts, they can potentially figure out what’s going on inside your computer. Read on and find out about the history of TEMPEST, modern research, and finally how you can try it out yourself at home!

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The Practical Potato Cell

Potato batteries, lemon batteries, they’re all good fun for the classroom — but is there a way of making them better? [Marcel Varallo] decided to give it a shot — and we gotta admit, it’s a pretty cool idea!

Normally for these fruit and vegetable batteries you poke some leads into the battery, connect it to a clock, and bob’s your uncle. But what if we made them resemble batteries? [Marcel] took some copper pipe, cut it down to size, and poked it through a potato. Now he had a potato-cored, copper tube. Stick a zinc nail in the middle, and you’ve got yourself a battery cell! Or as [Marcel] likes to put it.. a Mar-Cell. Or the more scientific term.. the Solanum tuberosum based electron differencer V1.0.

Each potato cell produces approximately 0.8V, so if you throw eight in series, you’ll have the equivalent of a 6V battery, just maybe not the same mAh rating.

For another cool way to demonstrate electricity to youngsters, we love this lemon battery hack — it’s actually quite elegant.

Electronic Ruler Works Out Logic Truth Tables

Like [Brad], we’ve seen a number of PCB rulers out there. [Brad] was looking to take the idea and run with it. His DigiRule is a ruler with a logic gate simulator. What he built is a mash-up between PCB rulers, and the concept of electronic business cards.

All told it simulates seven logic gates, four flip-flops, and includes a four-bit counter. On one end of the ruler a CR1220 battery feeds the 18F43K20 which is performing the logic operations using buttons and LEDs. Of course the truth tables are printed on the back silk-screen, but playing with the lights is a lot more fun. We do find it fairly amusing that the centimeters on the bottom of the ruler are notated in binary.

It makes a lot more sense to hand out rulers than business cards; people might actually use them after you leave and you can still include contact info. This form-factor also breaks the mold. You can have a lot more space on a ruler and you’re not constrained by thickness (although [Limpkin] solved that problem). While we’re on the topic of business cards [ch00f’s] USB etch-a-sketch style card and this logic-based information delivery device top our favorites list.

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Citizen Scientist: Forrest Mims

Before the modern notion of the citizen scientist lies the earlier ideal of the independent scientist. Scientists outside of the academic community but engaging with it. These days citizen scientists are often seen as valuable assistants in the scientific process, helping collect and process data in a quantity which would be otherwise intractable.

In the past however, independent scientists had a far more central role. Galileo, Kepler, Darwin and Hooke were all self funded at various points in their careers. More recently independent scientist Peter Mitchell won the Nobel prize for Chemistry in 1978 for his foundational research into cell biochemistry and the development of the chemiosmotic hypothesis.

Sadly, peer-reviewed scientific contributions by scientists un-sponsored by a research organization are now few and far between. In this short series we hope to highlight the efforts of these lone researchers with particular reference to the tools they’ve had to hack together on a budget in their scientific quests (if you know an independent researcher you think we should feature, please comment below!).

In Hacker circles Forrest Mims is perhaps best known for his series of electronics books and the unforgeable Atari Punk Console. But it’s his ability to engage with the scientific community as an independent researcher through a series of well thought out scientific articles that interests us here. Contributions made all the more significant by his lack of formal scientific training.

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Jewelry Meets Carpentry with Bentwood Rings

[Dorkyducks] is a bit of a jeweler, a bit of a carpenter, and a bit of a hacker.  They’ve taken some time to document their technique for making bentwood rings. Bentwood is technique of wetting or steaming wood, then bending or forming it into new shapes. While the technique is centuries old, this version gets a bit of help from a modern heat source: The microwave oven. [Dorkyducks] starts with strips of veneer, either 1/36″ or 1/42″ thick. The veneer is cut into strips 1/2″ wide by about 12″ long, wrapped in a wet paper towel, and microwaved. The microwaveglue-roll heats the water in the towel, steaming it into the wood. This softens the wood fibers, making the entire strip flexible. The softened wood is then wrapped around a wooden preform dowel and allowed to dry for a day or two.

Once dry, the wood will hold the circular shape of the dowel. [Dorkyducks] then uses masking tape to tack the wood down to a new dowel which is the proper ring size for the wearer. Then it’s a superglue and wrapping game. The glue holds the laminated veneer together, and gives the ring it’s strength. From there it’s sanding, sanding, sanding. At this point, the ring can be shaped, and inlays added. [Dorkyducks] shows how to carve a ring and insert a gemstone in this gallery. The final finish is beeswax and walnut oil, though we’d probably go for something a bit longer lasting – like polyurethane.

Heathkit: Live, Die, Repeat

There is no company that has earned more goodwill from electronic tinkering hobbyists than Heathkit. For more than fifty years, Heathkit has been the measure all other electronic kit manufacturers have been compared to. Kits for everything – from televisions to radios to computer terminals – were all sold by Heathkit, and even now, nearly a quarter century since the last kit left the warehouse, there is still a desire for this manufacturer to rise like a phoenix from the ashes. Heathkit lives once more, and this time it might be for real.

In recent years, Heathkit has had a confusing, if not troubled business plan. The company started manufacturing its signature products – electronic kits of every kind – in 1947. Production of these kits ended in 1992, and the company went on for another few years manufacturing educational materials and lighting controls. In 2011, Heathkit said they were back in the kit business, before shutting down a year later.

In 2013, an official Heathkit Facebook page was launched, a reddit AMA was held, and a mysterious stranger in the Hackaday comments section found a geocache placed by someone at Heathkit in a Brooklyn park. Absolutely nothing happened in 2014, or at least no one cared enough to hire a PI, which brings us to today’s announcement: Heathkit lives yet again.

This morning, the president of Heathkit sent a message to the ‘Heathkit Insiders’ email group explaining the goings on and new happenings:

We’ve designed and developed a wide range of entirely new kit products. We authored the manuals for these kits, complete with the beautiful line art you rely on, preserving and respecting our iconic historic Heathkit style. We developed many new inventions and filed patents on them. We relocated Heathkit, and set up a factory, and a warehouse, and offices, in Santa Cruz, California, near Silicon Valley. We built the back office infrastructure, vendor and supply chain relationships, systems, procedures, operations methods, and well-thought-out corporate structure that a manufacturing company needs to support its customers, to allow us to scale instantly the day we resume major kit sales. All this effort enables us to introduce a fleet of new kits and helps ensure Heathkit can grow, prosper, and continue to bring you great new products for a very long time.

The new Heathkit shop features their newest product, the Explorer Jr. AM Radio Receiver kit, a small kit radio available for $150. It’s actually a rather interesting kit with a nice design and an air variable cap for tuning, just like radios from a century ago. Whether anyone will pay $150 for an AM receiver in this century is another question entirely. The 21st century rebirth of Heathkit doesn’t just mean kits; they’re making apps now, with the first release being a crystal design tool for Android.

Virtually everyone in this little corner of the Internet, from Adafruit to Sparkfun, to Make magazine to everyone with a 3D printer owes a debt to Heathkit. This is the company that first turned DIY electronics into a successful business. Heathkit was the first, and they deserve to be recognized as the pioneers of the field.

The Donner Party were pioneers, too; just because you’re breaking new ground doesn’t mean you’re successful. The Heathkit of the 90s shuttered its doors for a reason. The factors behind the 1992 closing – cheap stuff from China, and the fact that not many people want to build their own electronics – are still with us. Still, the market for DIY electronics may be big enough, and Heathkit’s back catalog may be diverse enough that I won’t have to write another ‘Heathkit dies yet again’ post in a year or so. We can only hope.