Predicting The A-Bomb: The Cartmill Affair

January 18, 2024 by Al Williams 18 Comments

The cover of the infamous issue of Astounding, March 1944

There’s an upcoming movie, Argylle, about an author whose spy novels are a little too accurate, and she becomes a target of a real-life spy game. We haven’t seen the movie, but it made us think of a similar espionage caper from 1944 involving science fiction author Cleve Cartmill. The whole thing played out in the pages of Astounding magazine (now Analog) and involved several other science fiction luminaries ranging from John W. Campbell to Isaac Asimov. It is a great story about how science is — well, science — and no amount of secrecy or legislation can hide it.

In 1943, Cartmill queried Campbell about the possibility of a story that would be known as “Deadline.” It wasn’t his first story, nor would it be his last. But it nearly put him in a Federal prison. Why? The story dealt with an atomic bomb.

Nothing New

By itself, that’s probably not a big deal. H.G. Wells wrote “The World Set Free” in 1914, where he predicted nuclear weapons. But in 1914, it wasn’t clear how that would work exactly. Wells mentioned “uranium and thorium” and wrote a reasonable account of the destructive power: Continue reading “Predicting The A-Bomb: The Cartmill Affair” →

Need A Refresher On RMS?

January 16, 2024 by Al Williams 21 Comments

If you mostly deal with DC current, you might not think much of root mean square or RMS measurements. Sure, you’ve seen meters that have “true RMS” settings, but what does it mean? If you don’t know — or you want a refresher — watch [Prof MAD’s] recent video explaining the topic.

There are two things to remember when working with RMS. If you put, say, 100VDC through a 100-ohm resistor, you’ll draw 1A and use 100W of power. However, since AC gradually makes its way to a peak value and then starts ramping down immediately, you can’t use the peak value or anything like it to figure out AC power. After all, the voltage is only at that peak for an instant. That’s where RMS comes in. 100 VAC RMS through a 100-ohm resistor will also consume an average of 100W over time.

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E-Ink Photo Frame Is A Simple, Pleasing Design

January 11, 2024 by Lewin Day 3 Comments

Regular photo frames are good, but they tend to only display a single photo unless you pull them to bits and swap out what’s inside. [Ben] decided to make a digital photo frame using an e-ink display to change things up, and unlike some commercial versions we’ve seen, it’s actually pretty tasteful!

The build is based on a Nook Simple Touch Reader, which can be had pretty cheaply on the used market. It was chosen for the fact it runs Android, which makes it comparatively easy to hack and customize compared to some other e-readers on the market. Once it’s running a custom Android brew, it can be set to run an app called Electric Sign which simply shows a given website fullscreen and updates it at regular intervals. That turns the Nook into a remotely updateable photo frame in one fell swoop. From there, it just took a little trickery to access an iCloud album to update the frame with fresh pics. Then [Ben] just had to customize a nice photo frame to neatly mount the e-reader with room for the cable to subtly snake out the back.

It’s a simple build that relies on some existing tools already laying around the Internet. That’s nice, because it makes it easy for anyone to replicate themselves at home given the same materials. We’ve seen some other great digital photo frames before, too. If you’ve built your own neat and creative way to display your pics, don’t hesitate to drop us a line!

19th Century Copy Machine: The Cyclostyle

January 10, 2024 by Al Williams 15 Comments

In the 2020s photocopiers are getting a bit exotic, although they are not gone yet. But these days, you are more likely to simply print multiple copies of a document. However, it wasn’t long ago that making a copy of a document was a tall order. Carbon paper was fine if you were typing and only needed a few copies. But in the late 1800s to early 1900s, several solutions were available, including a beautiful early mimeograph known as the Cyclostyle at [Our Own Devices], examined in the video below.

The Cyclostyle was possibly inspired by a hectograph (something we looked at before). The Cyclostyle was originally a special stylus used to remove wax from a paper stencil. Then, a process similar to screen printing would make copies for you.

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Darkroom Robot Automates Away The Tedium Of Film Developing

January 8, 2024 by Dan Maloney 14 Comments

Anyone who has ever processed real analog film in a darkroom probably remembers two things: the awkward fumbling in absolute darkness while trying to get the film loaded into the developing reel, and the tedium of getting the timing for each solution just right. This automatic film-developing machine can’t help much with the former, but it more than makes up for that by taking care of the latter.

For those who haven’t experienced the pleasures of the darkroom — and we mean that sincerely; watching images appear before your eyes is straight magic — film processing is divided into two phases: developing the exposed film from the camera, and making prints from the film. [kauzerei]’s machine automates development and centers around a modified developing tank and a set of vessels for the various solutions needed for different film processes. Pumps and solenoid valves control the flow of solutions in and out of the developing tank, while a servo mounted on the tank’s cover gently rotates the reel to keep the film exposed to fresh solutions; proper agitation is the secret sauce of film developing.

The developing machine has a lot of other nice features that really should help with getting consistent results. The developing tank sits on a strain gauge, to ensure the proper amount of each solution is added. To avoid splotches that can come from using plain tap water, rinse water is filtered using a household drinking water pitcher. The entire rig can be submerged in a heated water bath for a consistent temperature during processing. And, with four solution reservoirs, the machine is adaptable to multiple processes. [kauzerei] lists black and white and C41 color negative processes, but we’d imagine it would be easy to support a color slide process like E6 too.

This looks like a great build, and while it’s not the first darkroom bot we’ve seen — we even featured one made from Lego Technics once upon a time — this one has us itching to get back into the darkroom again.

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Liquid Tin Could Be The Key To Cheap, Plentiful Grid Storage

January 8, 2024 by Lewin Day 143 Comments

Once expensive and difficult to implement, renewable energy solutions like wind and solar are now often the cheapest options available for generating electricity for the grid. However, there are still some issues around the non-continuous supply from these sources, with grid storage becoming a key technology to keep the lights on around the clock.

In the quest for cost-effective grid storage, a new player has entered the arena with a bold claim: a thermal battery technology that’s not only more than 10 times cheaper than lithium-ion batteries, but also a standout in efficiency compared to traditional thermal battery designs. Fourth Power is making waves with its “sun in a box” energy storage technology, and aims to prove its capabilities with an ambitious 1-MWh prototype.

Hot Stuff

Simple heating elements turn electricity into heat, putting it into liquid tin that then heats large graphite blocks. Credit: Fourth Power, Vimeo screenshot

The principle behind Fourth Power’s technology is deceptively simple: when there’s excess renewable energy available, use it to heat something up. The electrical energy is thus converted and stored as heat, with the idea being to convert it back to electricity when needed, such as at night time or when the wind isn’t blowing. This concept isn’t entirely new; other companies have explored doing this with everything from bricks to molten salt. Fourth Power’s approach involves heating large blocks of graphite to extremely high temperatures — as high as 2,500 °C (4,530 °F). Naturally, the hotter you go, the more energy you can store. Where the company’s concept gets interesting is how it plans to recover the heat energy and turn it back into electricity.

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An Adjustable High-Voltage Power Supply Built With Safety In Mind

January 6, 2024 by Dan Maloney 11 Comments

It’s not entirely clear why [Advanced Tinkering] needs a 50,000-volt power supply, but given the amount of work he put into this one, we’re going to guess it will be something interesting.

The stated specs for this power supply are pretty simple: a power supply that can be adjusted between 20kV and 50kV. The unstated spec is just as important: don’t kill yourself or anyone else in the process. To that end, [Advanced] put much effort into making things as safe as possible. The basic architecture of the supply is pretty straightforward, with a ZVS driver and an AC flyback transformer. Powered by a 24-volt DC supply and an adjustable DC-DC converter, that setup alone yields something around 20kV — not too shabby, but still far short of the spec. The final push to the final voltage is thanks to a three-stage Cockcroft-Walton multiplier made with satisfyingly chunky capacitors and diodes. To ensure everything stays safe in the high-voltage stage, he took the precaution of potting everything in epoxy. Good thing, too; tests before potting showed arcing in the CW multiplier despite large isolation slots in the PCB.

Aside from the potting, some really interesting details went into this build, especially on the high-voltage side. The 3D-printed and epoxy-filled HV connector is pretty cool, as is the special wire needed to keep arcs at bay. The whole build is nicely detailed, too, with care taken to bond each panel of the rack-mount case to a common ground point.

It’s a nice build, and we can’t wait to see what [Advanced Tinkering] does with it. In the meantime, if you want to get up to speed on handling high voltage safely, check out our HV primer.

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