A Modern Take On The “Paperclip Computer”

February 8, 2020 by Tom Nardi 44 Comments

Back in 1968, a book titled “How to Build a Working Digital Computer” claimed that the sufficiently dedicated reader could assemble their own functioning computer at home using easily obtainable components. Most notably, the design utilized many elements that were fashioned from bent paperclips. It’s unclear how many readers actually assembled one of these so-called “Paperclip Computers”, but today we’re happy to report that [Mike Gardi] has completed his interpretation of the 50+ year old homebrew computer.

The purist might be disappointed to see how far [Mike] has strayed from the original, but we see his embrace of modern construction techniques as a necessary upgrade. He’s recreated the individual computer components as they were described in the book, but this time plywood and wheat bulbs have given way to 3D printed panels and LEDs. While the details may be different, the end goal is the same: a programmable digital computer on a scale that can be understood by the operator.

To say that [Mike] did a good job of documenting his build would be an understatement. He’s spent the last several months covering every aspect of the build on Hackaday.io, giving his followers a fantastic look at what goes into a project of this magnitude. He might not have bent many paperclips for his Working Digital Computer (WDC-1), but he certainly designed and fabricated plenty of impressive custom components. We wouldn’t be surprised if some of them, such as the 3D printed slide switch we covered last month, started showing up in other projects.

While the WDC-1 is his latest and certainly greatest triumph, [Mike] is no stranger to recreating early digital computers. We’ve been bringing you word of his impressive replicas for some time now, and each entry has been even more impressive than the last. With the WDC-1 setting the bar so high, we can’t wait to see what he comes up with next.

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A 3.3 V Tube Preamp Without An Inverter

February 8, 2020 by Jenny List 34 Comments

If you’ve ever worked with vacuum tubes, you’ll probably have a healthy appreciation for high voltage power supplies. These components require higher potentials to get those electrons moving, or so we’re told. It’s not the whole truth though, as [Albert van Dalen] demonstrates with his tube preamplifier running from only 3.3 V. If your first thought is that he must have made a flyback converter to step that voltage up to something more useful then you’re in for a surprise, because the single 6J6 pentode really does run from just 3.3 volts. Even its heater, normally supplied with 6.3 V, takes the lower voltage.

The circuit appears at first sight to be a conventional single-ended design, but closer examination reveals a grid bias circuit more reminiscent of a bipolar transistor. This results in a positive grid voltage rather than the more usual negative, and an unusually high 0.3 mA grid current. The cathode current is only 0.15 mA, but the preamplifier delivers a 3.5x gain. There is more detail on his website.

It would be interesting to subject this circuit to a full audio analysis and comparison with a more conventional design. As with so much in the world of audio there’s some smoke and mirrors around what constitutes the so-called “valve sound”, and it’s a question whether the satisfaction comes through the sound itself or the bragging rights of having a unit with a vacuum tube on show. Still, this is a simple enough design which takes few resources to build, so we look forward to seeing further experimentation. Careful though – down the vacuum audio route can lie folly.

An Arcade Cabinet With Displays To Spare

January 31, 2020 by Tom Nardi 15 Comments

We’ve all got a pretty good mental image of what an arcade cabinet looks like, so you probably don’t need to be reminded that traditionally they are single-screen affairs. But that idea dates back to when they were built around big and bulky CRT displays. Now that we have modern LCD, LED, and OLED panels, who says you have to follow the old rules?

That’s precisely the sort of out of the box thinking that lead [Al Linke] to build this unique multi-display arcade cabinet. The game itself is still played on a single screen, but several smaller sub-displays are dotted all around the cabinet to indicate various bits of ancillary information. Are they necessary? Hardly. But we can’t deny it’s a clever idea, and we wouldn’t be surprised if we start seeing something similar in other DIY cabinets.

The build started with a commercially available cabinet from Arcade1Up, which at this point are popular enough that some of the Big Box retailers have them in stock. All of the electronics except for the display were stripped out, and replaced with a Dell OptiPlex 9020 computer and high-quality joysticks and buttons. [Al] then installed his various displays all over the cabinet, including a gorgeous LED marquee that we’ve featured previously.

So what do all these little screens do? [Al] explains them in the video after the break, but the general idea is that they provide contextual information about the game you currently have loaded up. A two-color OLED display shows the name of the game and what it’s rated, while a seven segment LED display shows the year the game was released. The displays are located both by the controls and where you’d expect the coin slot to be, so whether you’re actively playing or across the room, you can see all the information.

We’re always amazed to see how builders find ways to make their own personal arcade cabinets stand out. While it’s an idea that at this point we’ve seen quite a lot of, no two projects have ever been quite the same.

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Water Switch Lamp Illuminates Current Flow

January 31, 2020 by Kristina Panos 25 Comments

They always told you not to mix water and electricity. And while yes, that is good general advice regarding the two, you won’t rip a hole in the fabric of space-time should you go about it responsibly. Water will conduct electricity, so why not use it to switch on a lamp?

[Manvith Subraya]’s Hydro Lamp is, among other things, a reminder not to let Big Switch dim your idea of what’s possible with simple components. Switches don’t have to be complex, and some of the most reliable switches are pretty simple — the reed switch and the mercury tilt switch are good examples. By salinating the water at a ratio of 1:1, [Manvith] ensures power will flow through the acrylic tank, completing the circuit and lighting the 20W LEDs in both ends.

The brief demo video after the break sheds light on an interesting aspect of using water as a tilt switch — it’s not instantaneous. As he slowly moves the lamp from vertical to horizontal and back again, the light brightens and dims with the tide of electrons. We think it would be interesting to build a motorized frame that takes advantage of this for mood lighting purposes, especially if there were a few LEDs positioned behind the water.

Water is often used to explain the basic principle of current flow and the relationship dynamics of voltage, current, and resistance. As we saw in this water computer, the concept flows all the way into logic gates.

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ESP32 Serial Interface Modernizes Old Equipment

January 27, 2020 by Tom Nardi 25 Comments

There’s still plenty of useful hardware out there that uses an RS-232 interface, like the Behringer Ultradrive loudspeaker systems that [Lasse Lukkari] works with from time to time. Rather than ditch perfectly good gear because modern computers (to say nothing of phones or tablets) don’t have physical serial ports, he decided to come up with a WiFi adapter for these old devices that he calls SerialChiller.

Inside the SerialChiller is an ESP32, a MAX3232 line driver, a LM1117 linear regulator, and a few passives. The professionally manufactured PCB is housed inside of an enclosure that [Lasse] has repurposed from a cheap DB15 breakout adapter. The USB cable is used to power the board and for programming, though it can also be used to turn the SerialChiller into a USB-to-serial cable as well.

The hardware for this project is pretty straightforward, but what we really like is the direction he’s taken with the software. Rather than using the SerialChiller as a simple serial to WiFi bridge, [Lasse] is actually implementing a complete web-based interface directly on the microcontroller. In the video after the break he demonstrates his firmware for controlling the aforementioned Behringer Ultradrive, but that’s just one possible application for the project. Firmware could be spun up for all sorts of classic devices, breathing new life into hardware that might otherwise be in danger of heading to the landfill.

Of course, using the ESP family of chips as serial adapters is hardly anything new. In fact, that’s what they were designed for. But developing modern user interfaces for old hardware thanks to the power of the ESP32 has some fascinating potential.

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A Custom Raspberry Pi 4 Arcade Cabinet

January 25, 2020 by Tom Nardi 29 Comments

Over the years we’ve covered quite a few Raspberry Pi based arcade cabinets, and admittedly many of them have been fairly similar. After all, there’s only so much variation you can make before it stops looking like a traditional arcade machine. But even still, we never tire of seeing a well executed build like the one [Dawid Zittrich] recently shared with us.

These days you can order a kit that has pre-cut panels to build your cabinet with, but looking for a completely custom build, [Dawid] decided to first model his design in SketchUp and then cut out the panels himself with a jigsaw. This obviously is quite a bit more work, and assumes you’ve got sufficient woodworking tools, but we think the final result looks great. Not to mention the fact that it’s going to be a lot stronger than something made out of MDF.

He also created the side artwork himself, taking the logos and names from his favorite arcade and Amiga games and putting them on a retro-looking gradient pattern. The marquee on the top has an acrylic front and is illuminated from behind with strips of LEDs. It’s mounted on a hinge so that it can be lifted up and a new piece of art slid in without taking apart the whole cabinet. While it might be a little more labor intensive to switch out than some of the electronic marquees we’ve seen, we do like that you still have the ability to change the artwork on a whim.

With the cabinet itself completed, [Dawid] turned his attention to the electronics. Inside you’ve got the aforementioned Raspberry Pi 4 (with a Noctua fan to keep it cool), an external hard drive, a HDMI to VGA converter with scanline generator to drive the 4:3 ratio Eizo Flex Scan S2100 monitor, and a rather beefy amplifier hanging off the Pi’s 3.5 mm analog audio output. All of which is easily accessible via a maintenance hatch built into the cabinet so [Dawid] doesn’t need to tear everything down when he wants to tweak something.

If you’d like to have that arcade cabinet feel but don’t have the space and equipment to put something like this together, you could always stick a Raspberry Pi into an iCade and call it a day.

A Retro Touch Pad You Can Use On Modern Computers

January 22, 2020 by Tom Nardi 11 Comments

As [Jan Derogee] explains in the faux-retro video after the break, drawing on classic 8-bit computers was something of a pain. The rudimentary light pens and joysticks of the 1980s allowed for free-form input, but were clumsy and awkward to use. Which is why he set out to create an ideal drawing device for the C64 using modern electronics. For the sake of completion, he also gave it a USB HID mode so it would work on somewhat more modern computers.

His device, which he’s calling the Commo Pad, looks like it could have been transported here directly from the 1980s, but it’s built from entirely new hardware. The case is actually made of wood that [Jan] sanded and painted to give it that chunky plastic aesthetic that we all know and love, and the retro artwork on the touch panel really goes a long way to sell the vintage vibe.

Speaking of which, the touch panel is perhaps the most interesting component of the entire build. It’s actually a resistive panel that was meant for mounting to an LCD that [Jan] has connected to an Arduino. All he had to do was provide a stable frame for it and print out some art work to slide in behind it.

The Arduino and associated electronics allow the Commo Pad to be picked up by the C64 as either a joystick or mouse, which means it doesn’t need any custom software on the computer side to function. Similarly, it can also mimic a USB mouse if you want to plug it into something made a bit later than 1982. Should you be so inclined to make it wireless, the addition of a Bluetooth seems like it would be relatively trivial.

If the Commo Pad doesn’t have enough of a retro-futuristic vibe for your tastes, we recently covered a custom optical touch panel that looked like it could double as a prop from Blade Runner which might do the trick.

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