Raspberry Pi Simulates The Real Analog TV Experience

June 20, 2022 by Dan Maloney 18 Comments

If you’ve laid hands on a retro analog TV, have the restoration bug, and you plan to make the final project at least somewhat period-correct, you face a bit of a conundrum: what are you going to watch? Sure, you can serve up just about any content digitally these days, but some programs just don’t feel right on an old TV. And even if you do get suitably retro programming, streaming isn’t quite the same as the experience of tuning your way through the somewhat meager selections as we did back in the analog days.

But don’t worry — this Raspberry Pi TV simulator can make your streaming experience just like the analog TV experience of yore. It comes to us from [Rodrigo], who found a slightly abused 5″ black-and-white portable TV that was just right for the modification. The battery compartment underneath the set made the perfect place to mount a Pi, which takes care of streaming a variety of old movies and shorts. The position of the original tuning potentiometer is read by an Arduino, which tells the Pi which “channel” you’re currently tuned to.

Composite video is fed from the Pi’s output right into the TV’s video input, and the image quality is just about what you’d expect. But for our money, the thing that really sells this is the use of a relay to switch the TV’s tuner back into the circuit for a short bit between channel changes. This gives a realistic burst of static and snow, just like we endured in the old days. Hats off to [Rodrigo] for capturing everything that was awful about TV back in the day — Mesa of Lost Women, indeed! — but still managing to make it look good.

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Wooden You Like To Hear A CNC-Cut Phonograph Record?

June 17, 2022 by Dan Maloney 22 Comments

Say what you will about [Thomas Edison], but it’s hard to deny the genius of his self-proclaimed personal favorite invention: the phonograph. Capturing sound as physical patterns on a malleable medium was truly revolutionary, and the basic technology that served as the primary medium of recorded sound for more than a century and built several major industries is still alive and kicking today.

With so much technological history behind it, what’s the aspiring inventor to do when the urge to spin your own phonograph records strikes? Easy — cut them from wood with a CNC router. At least that’s how [alnwlsn] rolled after the “one-percent inspiration” hit him while cutting a PCB with his router. Reasoning that the tracks on the copper were probably about as fine as the groove on a record, he came up with some math to describe a fine-pitch spiral groove and overlay data from a sound file, and turn the whole thing into G-code.

For a suitable medium, he turned to the MDF spoil board used to ship PCB stencils, which after about three hours of milling resulted in a rather hairy-looking 78-RPM record. Surprisingly, the record worked fairly well on a wind-up Victrola. The spring-powered motor was a little weak for the heavy wooden record and needed a manual assist, but you can more or less clearly hear the 40-second recording. Even more surprising was how much better the recording sounded when the steel needle was replaced with a chunk of toothpick. You can check out the whole thing in the video below, and you’ll find the G-code generation scripts over on GitHub.

Is all this talk about reproducing music using wiggly lines confusing you? Woah, there, whippersnapper — check out [Jenny]’s primer for the MP3 generation for the background you need.

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The Secrets Of The Pop Pop Boat

June 13, 2022 by Adam Fabio 28 Comments

Many kids get an early introduction to mechanics with tin pop-pop boats. If you haven’t played with one – you’re missing out! Pop Pop boats are fun toys – but how they work is often misunderstood. To clear this up, [Steve Mould] takes a deep dive into the theory of operation of the pop pop boat.

Most people think these toys operate like a simple steam engine, with water being flashed into steam inside a tiny tin boiler. Turns out that’s not the case. To explain the physics, [Steve] commissioned a glass version of the boat.

The glass boat shows that during normal operation, there isn’t any water at all in the “boiler” at all. The water is only in the boat’s small exhaust tubes. The air inside the tank is heated by a candle. The air expands and pushes the water out of the tubes. This allows the air to cool, and return to the tank. The water then rushes back up the tubes, and the process repeats.

One of the more interesting facts of the video is that the glass boat doesn’t pop. The popping sound associated with the boat is actually made by the tin diaphragm on top of the “boiler”.

[Steve] has gotten pretty good at explaining complex topics using clear cutaway models. If this tickles your fancy, check out his water computer.

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A PCB with an Arduino Micro Pro, RCA connectors and a sub-D connector

Odd Inputs And Peculiar Peripherals: Using A Commodore Light Pen On A Modern(ish) Computer

June 11, 2022 by Robin Kearey 8 Comments

If you worked with computers back in the 1970s, there’s a good chance you used a light pen at some point: a simple input device that you’d point at the CRT screen to highlight text, choose menu options or manipulate graphic objects. Although ubiquitous in those days, the light pen lost the battle for ergonomics to the humble mouse and was all but extinct by the late 1980s. Touchscreen styluses implement a similar function today, but touching the screen somehow doesn’t feel the same as simply pointing at it.

We therefore applaud [Maciej Witkowiak]’s efforts to bring the light pen into the 21st century by building a USB interface for a Commodore 64/128 light pen. At its heart is an Arduino Micro Pro that implements the USB HID protocol to communicate with any modern computer. It connects to the classic light pen as well as to the computer’s analog display signal and uses those to calculate the delay between the video synchronization pulses and the light pen’s output. The sync pulses are extracted from the video signal by an LM1881, a sync separator chip that will be familiar to anyone who’s worked with analog video signals.

The Arduino calculates the light pen’s position based on the measured timing intervals and reports it to the computer, using the absolute positioning mode that’s also used by things like drawing pads. [Maciej] demonstrates his system in the video embedded below, in which he uses it to operate the menus on an X window system. A great success then, although there’s one catch: light pens only work on CRT displays, so you’ll need to drag one of those big glass beasts out of storage if you want to try this yourself.

We’ve featured the Commodore light pen before in this odd gaming input device. A similar device built with a discrete LED matrix is a good illustration of the light pen’s working principle.

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The Origin Of The Fresnel Lens

June 7, 2022 by Al Williams 15 Comments

If you are a Hackaday reader, you probably know what a Fresnel lens is. You find them in everything from overhead projectors to VR headsets. While it seems commonplace now, the Fresnel lens was an important invention for its day because it revolutionized maritime navigation and, according to a post over at IEEE Spectrum, that was the driving force behind its invention. In fact, the lens has been called “the invention that saved a million ships“.

The problem stems from issues in navigation. Navigating by the sun and the stars is fine, but not workable when you have heavy cloud cover, or other reasons you can’t see them. A lighthouse often marked an important point that you either wanted to navigate towards or, sometimes, away from. Sure, today, we have GPS, but for a long time, a lighthouse was your best bet.

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Surprisingly Stomp-able Soft Switches

June 2, 2022 by Kristina Panos 13 Comments

Competition sure brings out the brute in people, doesn’t it? So what do you do when you need a bunch of switches you can let people fist-pound or stomp on repeatedly without them taking damage? You could look to the guitar pedal industry and their tough latching switches, or you could simply build your own smash-resistant buttons as [wannabemadsci] has done.

The main thing about these switches is that they aren’t easily destroyed by shoes or angry fists. That’s because the shiny red push-me part of the button is made by cutting a foam ball in half.

Not easily crush-able Styrofoam, mind you — squishy, coated foam like an indoor football. This is mounted to the top of a sandwich made of hardboard and a couple pieces of easily-compressible foam from craft paintbrushes.

A brass washer is mounted to the middle of both pieces of hardboard, and these have wires soldered to them to read button presses. Then it’s just a matter of hooking it to a microcontroller like any other momentary.

There are all kinds of things you could cut in half for the top, like maybe tennis balls. Or, do what [Sprite_TM] did and use inverted plastic bowls.

The LackRack Enterprise Edition in Revspace, Netherlands

Rackmount Hardware Placement Issues? IKEA LACK To The Rescue!

May 29, 2022 by Arya Voronova 18 Comments

[hackbyte] reminds us about a classic hack that, even though we’ve seen floating around for over a decade, has somehow never quite graced our pages before. Many of us keep small home labs and even, at times, collections of servers that we’d be comfortable be calling mini-datacenters. However, if you use the ever-abundant 19″ switches, servers and other hardware, keeping these mounted and out of the way can be a thorny experience. Which leads us to, undoubtedly, unintentional – but exceptionally handy – compatibility between IKEA LACK table series and 19″ rackmount hardware.

The half-humorous half-informative wiki page on Eth0Wiki talks about this idea in depth, providing a myriad of examples and linking to pages of other hackerspaces and entities who implemented this idea and improved upon it. These tables look nice and fit anywhere, stack neatly when not in use, and you can put a bottle of Club-Mate on top. Aka, they’re the exact opposite of cheap clunky cabinets actually designed for rackmount you can buy, and cost a fraction of the price. What’s not to love?

You can buy a whole lot of cheap hardware in 19″, and arguably, that’s where you can get the best hardware for your dollar. Many a hackerspace has used these tables for makeshift infrastructure, permanent in all but intent. So, in case some of us missed the memo, now you are aware of yet another, underappreciated solution for mounting all these servers we get for cheap when yet another company replaces its equipment – or undergoes a liquidation. If LackRack hasn’t been on your radar – what have you been using for housing your rackmount hardware collection?

Wondering what to do with an old server? Building a powerful workstation is definitely on the list. Alternatively, you could discard the internals and stuff it full of Raspberry Pi!