Old-School Video Switching Levels Up With Modern USB Control

Video effects and mixing are done digitally today, but it wasn’t always so. When analog ruled the video world, a big switch panel was key to effective results.

VIdeo like this was the result of combining different analog feeds with different effects. The better the hardware, the more was possible.

Devices like [Glen]’s Grass Valley Series 300 Crosspoint Switch Panel were an important part of that world. With tools like that, a human operator could set up a composited preview feed in true WYSIWYG style, and switch to live on cue. All done with relatively simple CMOS ICs and buttons. Lots and lots of buttons.

[Glen] reverse engineers the panel to show how it works, and most of the heavy lifting is done by the MC14051B analog multiplexer/demultiplexer, and the MC14532B 8-bit priority encoder. Once that’s figured out, the door is open to modernizing things a little by using a microcontroller to drive the device, turning it into a USB peripheral.

With a little design work, [Glen] builds a PCB around the EFM8UB2 8-bit microcontroller to act as a USB peripheral and control the switch panel, taking care of things like key scanning and lamp control. The last step: a GUI application for monitoring and controlling the panel over USB.

This isn’t [Glen]’s first time interfacing to vintage video mixing and switching, and as many of us know it’s sometimes tricky work to interface to existing hardware. We covered his earlier video switcher project using hardware that was not nearly as easy to work with as this one.

Power Up Vintage Electronics Less Unsafely With A Dim-Bulb Tester

Plugging in something like an antique radio to see if it works is a good way to have a bad time, because some old components don’t age well. For vintage electronics, inspection and repair are steps one and two. When it comes time to cautiously apply power, it’s best to use what’s called a dim-bulb tester and most hackers can probably put one together from scrap.

Being able to use one (or both) bulbs adds some flexibility, and the embedded power monitor is an inexpensive and handy addition.

These testers make it easier, and safer, to tell if there are any big problems with a device’s power supply. In its simplest form, a dim-bulb tester puts an incandescent lamp in series between a device — like an old radio — and the AC power from a wall socket. Thanks to this, if the device has a short circuit, the bulb will simply light up instead of causing any damage.

Ideally, one uses a bulb with a wattage rating that is roughly equal to the power consumption of the device being tested. If all is well, the bulb will glow very faintly and the device will work normally. A brightly glowing bulb would indicate excessive current draw. To allow some flexibility, [Doz]’s tester design allows using one or two 60 W incandescent bulbs in series, and even incorporates an inexpensive power monitor.

A dim-bulb tester isn’t an in-depth diagnostic tool but it is effective, simple, and allows for a safe startup even if there’s a serious problem like a short.  It helps protect valuable hardware from going up in smoke. In fact, the fundamental concept of limiting power to protect hardware in case of a fault has also been applied in the world of retrocomputing, where it helps protect otherwise irreplaceable hardware if something goes wrong.

A terminal window with a search for "Guineau Pig Olympics" is inset on a photo of an ortholinear keyboard attached by a yellow USB cable to a 70s aluminum and plastic Super 8 film editor/viewer. The device has a large screen on the right hand side, a silver grate on the left, and a tray at the bottom for slotting in film.

Super 8 Film Editor Reborn As A YouTube Terminal

We love hacks that give new life to old gadgets, and [edwardianpug]’s YouTube Terminal certainly fits the bill by putting new hardware inside a Super 8 film editor.

[edwardianpug] could have relegated this classy-looking piece of A/V history to a shelf for display, but instead she decided to refresh its components so it could display any YouTube video instead of just one strip of film at a time. The Boost-Box keeps the retrofuturistic theme going by using the terminal to search for and play videos via Ytfzf.

The original screen has been replaced by an 800×600 LCD, and the yellow USB cord gives a nice splash of color to connect the ortholinear keyboard to the device. Lest you think that this “ruined” a working piece of retro-tech, [edwardianpug] says that 20 minutes would get this device back to watching old movies.

Are you looking for more modern and retro mashups? Check out these Dice Towers Built In Beautiful Retro Cases, a Vacuum Tube and Microcontroller Ham Transmitter, or this Cyberdeck in a Retro Speaker.

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A Homemade Tube Amplifier Featuring Homemade Tubes

With the wealth of cheap and highly integrated audio amplifier modules on the market today, it takes a special dedication to roll your own from parts. Especially when those parts include vacuum tubes, and doubly so when you make the vacuum tubes from scratch too.

Now, we get it — some readers are going to find it hard to invest an hour in watching [jdflyback] make a pair of triodes to build his amplifier. But really, you’ve got to check this out. Making vacuum tubes with all the proper equipment — glassblower’s lathe, various kinds of oxy-fuel torches, all the right hand tools — is hard enough. But when your lathe is a cordless drill, and you’re using a spot welder that looks like it’s cobbled together from junk, your tube-making game gets a lot harder. Given all that, you’d expect the tubes to look a lot rougher than they are, but even with plain tungsten wire heaters and grids made from thick copper wire, they actually work pretty well. Sure, the heaters glow as bright as light bulbs, but that’s all part of the charm.

Speaking of charm, we just love the amp these tubes went into. Built in 1920s breadboard-style, the features some beautiful vintage mica capacitors and wirewound resistors, plus a variable resistor the likes of which we’ve never seen. The one nod to modernity is the clever use of doorbell transformers, one for a choke and one for the speaker transformer. They don’t sound great, but there’s no doubt they work.

We may have seen other homemade vacuum tubes before — we even recently featured a DIY X-ray tube — but there’s something about [jdflyback]’s tubes that really gets us going.

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Everything You Wanted To See About Restoring A 1956 Radio

Ever wanted a good, good look at the insides of a 1950s radio, along with fantastic commentary on the internals and the purpose of various components? Then don’t miss [Adam Wilson]’s repair and restoration of a 1956 Philips 353A, a task made easier by a digitized copy of the service manual. [Adam] provides loads of great pictures, as well as tips on what it takes to bring vintage electronics back to life. What’s not to like?

Vintage electronics like this are often chock-full of components that deteriorate with age, so one doesn’t simply apply power to see if it still works as a first step. These devices need to be inspected and serviced before power is ever applied. Even then, powerup should be done with a current-controlled source that can be shut down if anything seems amiss.

Thank goodness for high quality, digitized service manuals.

Devices like these largely predate printed circuit boards, so one can expect to see plenty of point-to-point soldering. Vacuum tubes did much of the hard work, so they are present instead of integrated circuits and transistors. Capacitors in the microfarads were much larger compared to their modern equivalents, and paper/wax capacitors (literally made from rolled-up paper covered in wax) handled capacitances in the nanofarad range instead of the little ceramic disk caps of today.

One thing that helped immensely is the previously-mentioned Philips 353A service manual, which includes not only a chassis and component layout, but even has servicing procedures such as cord replacement for the tuning dial. Back then, a tuning dial was an electromechanical assembly that used a winding of cord to rotate the tuning capacitor, and replacing it was a fiddly process. If only all hardware was documented so well!

The end result looks wonderful and still has great sound. As a final tweak, [Adam] added an external audio input cable as a nod to the modern age. Now, we have in the past seen a small LED screen integrated convincingly into an antique, but in this case [Adam] kept the original look completely intact. You can see it in action, playing some Frank Sinatra in the short video embedded below.
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Mac 128K Emulator Gets DIY Ceramic Enclosure

Creative technologist [Joselyn McDonald] wanted to hone her ceramic skills by building an iconic Macintosh 128K sculpture, complete with a fully functional operating system.

At first, she was determined to use Processing to create an interface for her sculpture by recreating the UI visually and adding some touch controls. However, she soon abandoned this tedious task after discovering MacintoshPi, which steps you through installing Mac OS 7, 8, and 9 emulators on a Raspberry Pi. [Joselyn] has also installed several retro games, including DOOM II, Carmen Sandiego, and Sim City, thanks to sites like Macintosh Garden and Macintosh Repository. 

Next, [Joselyn] hopes to set it up to display her and her partner’s schedules, and to let friends play around with nostalgic games. This piece was made using hand building, but other cool ceramic techniques like this slip cast dog bowl and this stone 3D printer have us thinking about what other types of enclosures could be built!

TRS-80 Gains Multiple Monitor Support, And High-Resolution Graphics

To call [Glen Kleinschmidt] a vintage computing enthusiast would be an understatement. Who else would add the ability to control and address multiple VGA monitors to a rack-mounted TRS-80 Model 1? Multiple 64-color 640×480 monitors might not be considered particularly amazing by today’s standards, but for 70s-era computing, it’s a different story.

Drawing this sin(x)/x ripple surface can be done in only 17 lines of BASIC.

How does a TRS-80 even manage to output anything useful to these monitors? [Glen] wrote his own low-level driver in machine code to handle that. The driver even has useful routines that are callable from within BASIC, meaning that programs written on the TRS-80 are granted powerful drawing abilities. Oh, and did we mention that the VGA graphics cards themselves were designed and made by [Glen]?

Interested in making your own? [Glen] provides all the resources you’ll need to re-create his work, including machine code drivers and demonstration BASIC programs as downloadable audio files, just as they would have been on original cassette tapes.

Watch things in action in the videos embedded below. The first draws a Land Rover, and the second plots a simple Moiré pattern star. Not bad for 70s-era hardware and 74xx logic!

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