# Building A Giant Boardgame Isn’t Easy

[Stevenson Streeper] is a maker, and was recently charged with a serious mission. He had to prototype, design, and build a board game. A software-controlled board game, that is, and one that was 400 square-feet in size. As you might imagine, this ended up being a tall order, and he’s been kind enough to share his tale on his blog.

His client’s idea was for a giant interactive game board akin to the glowing disco floors of old. It had to play a game approximating the rules of “The Floor Is Lava.” It had to handle up to 20 players at a time, too.

[Stevenson] runs a company that delivers “Activations”—basically big showpieces for customers willing to pay. This wasn’t his first attempt at building an immersive attraction, but it was a big job, and a challenging one at that. He explains the difficulties that came about from a limited crew, limited timeline, and a number of difficult missteps. Hurdles included surprise unusable off-the-shelf hardware and the difficulty of hand-sanding 144 tiles of polycarbonate. One weeps for the project’s plight early on – if only the AliExpress tiles were documented.

He may have bitten off more than he could chew, and yet—the project was finished and to a decent degree of functionality success. That’s to be applauded, and [Stevenson] learned a ton along the way. Big projects can be daunting and can put you in a bind. As this story demonstrates, though, perseverance often gets you somewhere okay in the end. Video after the break.

# Measuring An Unknown Velocity Factor

When is the speed of light not the speed of light? Of course, that’s a trick question. The speed of light may be constant, but just as sound travels at different speeds in different media, electronic signals move through transmission lines at a reduced speed. When you have a known cable, you can look up the velocity factor and use it to approximate the length of cable to have a given effective length. But what if you don’t know what kind of cable you have? [More Than Electronics] used a scope to measure it. You can see what he did in the video below.

For example, RG-8/U has a factor of 0.77. Even air isn’t exactly a factor of 1, although it is close enough that, in practice, we pretend that it is. If you wonder why it matters, consider stubs. Suppose you have a 300 MHz signal (handy because that’s 1 meter in wavelength; well, OK, pick 299.792 MHz if you prefer). If you have a quarter wavelength piece of coax shorted at one end, it will attenuate signals at 300 MHz. To understand why, picture the wave on the stub. If the close end of the stub is at 0 volts, then the other end — because it is a quarter wavelength away — must be at the maximum positive voltage or the minimum negative voltage. If either of the extremes is at the close end, then the far end must be at zero volts. That means the maximum current flows only when the signal is at 300 MHz.

# End-Of-Life For Z80 CPU And Peripherals Announced

In a Product Change Notification (PCN) published on April 15, Zilog (now owned by Littelfuse) announced the End of Life for a range of Z80 products, specifically virtually all of the Z84C00 range. This also includes the peripherals, such as the Z84C10 range of MPUs. These are currently already marked as EoL on stores like Mouser, with Littelfuse noting that the last orders with them can be placed until June 14th of 2024. After that you’ll have to try your luck with shady EBay sellers and a lucky box of old-new-stock found in the back of a warehouse.

What this effectively means is that after just under 48 years since its launch in 1976, the Zilog Z80 will no longer be available for sale as discrete components, which is likely to primarily impact hobbyists and people who are trying to keep retro systems going. This does not mean that it’s the end of the road for Z80, however, as the eZ80 will be produced for the foreseeable future.

These new chips will of course not come in easy to drop in DIPs, making the challenge of breadboarding your own Z80-based microcomputer that much tougher. Yet one thing that definitely won’t happen is any of us witnessing the end of the era of the Z80, 6502 and 8051 architectures.

Thanks to [Techokami] for the tip.

# Roboticizing An Etch-a-Sketch

The Etch-a-Sketch was a popular toy, but a polarizing one. You were either one of those kids that had the knack, or one of the kids that didn’t. [Micah] was pretty firmly in the latter group, so decided to roboticize the Etch-a-Sketch so a computer could draw for him instead.

The build uses a pair of stepper motors attached to the Etch-a-Sketch’s knobs via 3D-printed adapters. It took [Micah] a few revisions to get the right design and the right motors for the job, but it all came together. A Raspberry Pi is charged with driving the motors to draw the desired picture.

Beyond the mechanics, [Micah] also does a great job of explaining the challenges around drawing and the drive software. Namely, the Etch-a-Sketch has a major limitation in that there’s no way to move the stylus without drawing a line. He accounts for this in his code for converting and drawing images.

The robot draws slowly but surely. The final result is incredibly impressive, and far exceeds what most of us could achieve on by hand. We’ve seen some similar builds in the past, too. Video after the break.

# Crystal Radio Kit From The 1970s

If you read the December 1970 issue of Mechanix Illustrated, you’d be treated to [Len Buckwalter]’s crystal radio build. He called out Modern Radio Labs as the supplier for parts. That company, run by [Elmer Osterhoudt], got so many inquiries that he produced a kit, the #74 crystal set. [Michael Simpson] found an unopened kit on eBay and — after a bidding war, took possession of the kit. The kit looked totally untouched. The crystal detector was still in the box, and there were period-appropriate newspaper wrappings.

The kit itself isn’t that remarkable, but it is a classic. An oatmeal box serves as a coil form. There’s a capacitor, a crystal detector, and headphones. The original cost of the parts was \$7, but we imagine the eBay auction exceeded that by a large amount.

If the name [Len Buckwalter] sounds familiar, he was quite prolific in magazines like Electronics Illustrated and also wrote several books about transistors. [Michael] also shows off his innovative coil winder made from plastic cups and a coat hanger.

We’d love to find some old kits like this, although, from one way of thinking, it is almost a shame to build them after all these years. With an added audio amplifier and fiddling with the cat whisker, it sounded just fine.

If you don’t like oatmeal, you could fire up the 3D printer. While the basic circuit is simple, you can make it more complex if you like.

# Hackaday Podcast Episode 267: Metal Casting, Plasma Cutting, And A Spicy 555

What were some of the best posts on Hackaday last week? Elliot Williams and Al Williams decided there were too many to choose from, but they did take a sampling of the ones that caught their attention. This week’s picks were an eclectic mix of everything from metal casting and plasma cutters to radio astronomy and space telescope budgets. In between? Some basic circuit design, 3D printing, games, dogs, and software tools. Sound confusing? It won’t be, after you listen to this week’s podcast.