We think of punched cards as old-fashioned, but still squarely part of the computer age. Turns out, cards were in use way before they got conscripted by computers. Jacquard looms are one famous example. The U.S. Census famously used punched cards for tabulating the census without anything we’d consider a computer. But in the 1950s, you might have had a punched card machine on your electronics workbench. The Hickok Cardmatic was a tube tester with a difference.
About Tube Testers
While you, as a Hackaday reader, might tear into a busted TV at your house and try to fix it, most people today will either scrap a bad set or pay someone to fix it. That’s fine today. TVs are cheap and rarely break, anyway. But this hasn’t always been the case.
In the “good old days” your expensive TV broke down all the time. Most of the parts were reliable, but the tubes would wear out. If you were the kind of person who would change your own oil, you’d probably look to see if you could spot a burned out tube and try replacing it. If you couldn’t spot it, you’d pull all the tubes out. If you were lucky, there was a diagram glued inside the cover that showed where they all went back. Then you took them to the drugstore.
[Ed note: The project pages and video got pulled right when this went to press. Nicola received a takedown notice. We’ll let you know more when we do. The main link has been updated to the Wayback Machine.]
That’s not to say that the Ikea TRÅDFRI light bulb is the only thing [Nicola Wrachien] needed to accomplish the hack. But the bulb, specifically this addressable GU10 RGB LEB bulb, donated the most critical component, a Silicon Labs MGM210L wireless microcontroller, with enough processing power to run vanilla Doom. Added to the microcontroller was a TFT display, a controller made from a handful of buttons and a shift register, and a few odds and ends to stitch it all together. Some more memory was needed, though, so [Nicola] used an 8 MB QSPI flash memory and a couple of neat tricks to reduce latency and improve bandwidth. There are a lot of neat tricks with this one, but the coolest thing might just be that the whole footprint of the build isn’t that much bigger than the original bulb. Check out the surprisingly smooth gameplay in the video below.
We’ve seen many inventive enclosures for single board computers over the years: some are decorative, others utilitarian, and yet more tailored to an application. This one from [Daniel Hepper] manages to be all three: a practical enclosure for an OrangePi Zero LTS running the PiHole web spam filter, enclosed in a seemingly unopened Spam tin.
The inspiration came from an out-of-date tin of Spam, a souvenir that had lain around for a decade. It had a paper label that could be carefully removed, after which a Dremel was used to cut an aperture in the reverse of the tin. The tasty-but-expired luncheon meat could then be scooped out, and a 3D-printed carrier for the OrangePi slid in. The label reattached, it looks for all the world like an unopened tin of Spam with a PoE cable emerging from its behind.
[Ben Heck] found an old card-swipe point-of-sale box at the Goodwill store, took it home, and tore it down to see what was inside. He found a completely serviceable single board computer based on the Z80. In fact, there’s a whole family of four Z80 chips: the CPU itself, the DART chip (dual UART), the PIO chip (parallel input/output interface), and the CTC chip (counter/timer circuit). That’s not all — there’s a landline telephone modem, a real time clock, 32K of RAM and UV-EPROM. The second PCB of this assembly holds a hefty sixteen-key keypad and a sixteen-character vacuum fluorescent alphanumeric display. All this for the bargain price of $2.99.
Surely [Ben] will dig into the Z80 system in the future, but in this video he tries to make the display work. An OKI Semiconductor controller drives the VFD. After tracking down the data sheet, [Ben] wires it up to an Arduino and writes a quick program. Only a few YouTube minutes later, he conquers the display, drawing sample text anywhere he wants on the screen with any brightness he desires.
You never know what you may find lurking inside old equipment like this. You might find a proprietary ASIC with no documentation, or like [Ben] did here, you could find a fully functioning embedded computer. If [Ben] can whip up a RAM-based emulator to replace the 32K UV-EPROM, he’ll have a perfect evaluation board for Z80 projects.
Let us know in the comments if you have found any treasures like this. Also, how would you use this board if you had found it? Thanks to reader [Nikša Barlović] for sending in the tip.
There was a time when most 3D printers used ABS, which is a great plastic for toughness, but is hard to print with since it tends to warp. Worse still, it stinks and the fumes may be bad for you. Most people have switched over to printing in PLA these days, but one thing you might miss with this more forgiving plastic is vapor smoothing with acetone; a smoothed print doesn’t show layer lines and looks more like plastic part that didn’t go through a nozzle.
[Major Hardware] likes the look of vapor smoothed parts, but doesn’t like working with ABS and acetone fumes, so he’s started using Polysmooth. As you can see in the video below, the results look good, but be warned that the filament is relatively pricey. Plus you need to use a $300 machine that atomizes your alcohol into a mist. We feel certain you could do the same thing for less since it appears to just be like a humidifier, but we’d also suggest being careful putting flammable substances in a consumer-grade humidifier and certainly don’t use a vaporizer.
The filament sounds like it is on par with PLA for ease of printing. The material has a higher glass temperature than PLA but less than ABS. The tensile strength and Young’s modulus (a measure of stiffness) numbers are comparable to ABS. Although all smoothing has some imperfections and you probably need to experiment with times and other parameters. The smoothing did fuse some movable joints, so anything that moves or fits together is probably a bad candidate for this process. We’ve also heard that thin-walled parts can get soft in water due to alcohol residue, but you can dry or soak the part clean to avoid that.
If you want to try your own hand at making a mist, this might get you started. After all, if it can handle acetone, we imagine alcohol isn’t any worse. While it isn’t as easy to handle as alcohol, we hear the solvents such as THF or ethyl acetate can smooth regular PLA. Heat guns and open flames are popular, too.
Wouldn’t it be nice if every webcam had a hardware switch? Especially for those built-in webcams like the one in your laptop. Since they don’t have switches yet, we’re just stuck trying to remember to turn them off or re-apply the sticker after every meeting. [Becky Stern] was tired of trying to remember to blind the all-seeing eye, and decided to make a robot companion that would do it for her.
Essentially, a servo-driven, 3D-printed eyelid covers the eye’s iris and also the web cam directly underneath. At first, we though [Becky] had liberated the business parts of a cheap webcam and built it into the eyeball, but this is far less intrusive. The eyeball simply sits atop the monitor, and [Becky] can control the eyelid two ways: she can set a timer with the potentiometer to close it automatically after some number of minutes, or else do it on demand using the momentary button. We’d love to see it tied directly to Zoom and or whatever else [Becky] uses regularly. Be sure to check out the build and demo video after the break to see it in action.
In his case, [Michał] wanted to build a power strip that would cut the power to any devices plugged into it once his computer went to sleep. Unfortunately, he couldn’t just check to see if there was 5 V on the line as his motherboard kept the USB ports powered up all the time. But with some modifications to the relay board’s firmware, he reasoned he should be able to detect if there was any USB activity by watching for the start-of-frame packet that goes out every millisecond when the bus is active.
Now [Michał] isn’t claiming to be the first person to come up with a custom firmware for one of these boards, in fact, he credits an existing open source firmware project as an inspiration for his work. But he did create an entirely new GPLv3 firmware for these ATtiny45 powered devices, which includes among other improvements the latest version of V-USB. As it so happens, V-USB includes start-of-frame packet detection out of the box, which made it much easier to implement his activity detection code.
With the new firmware flashed to the relay board’s chip, [Michał] put it in an enclosure and wired up the outlets. But there was still one missing piece of the puzzle. It seems that Linux won’t actually send out the start-of-frame packets unless its actively communicating with a USB device, as part of the so-called “selective suspend” power saving feature. Luckily there is support for disabling this feature for specific devices based on their Vendor/Product ID pair, so after a little udev fiddling, everything was working as expected.