[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.
We’ll just go ahead and say it right up front: we love teardowns. Ripping into old gear and seeing how engineers solved problems — or didn’t — is endlessly fascinating, even for everyday devices like printers and radios. But where teardowns really get interesting is when the target is something so odd and so specialized that you wouldn’t normally expect to get a peek at the outside, let alone tramp through its guts.
[Mads Barnkob] happened upon one such item, a Fujifilm FCR XG-1 digital radiography scanner. The once expensive and still very heavy piece of medical equipment was sort of a “digital film system” that a practitioner could use to replace the old-fashioned silver-based films used in radiography, without going all-in on a completely new digital X-ray suite. It’s a complex piece of equipment, the engineering of which yields a lot of extremely interesting details.
The video below is the third part of [Mads]’ series, where he zeroes in on the object of his desire: the machine’s photomultiplier tube. The stuff that surrounds the tube, though, is the real star, at least to us; that bent acrylic light pipe alone is worth the price of admission. Previous videos focused on the laser scanner unit inside the machine, as well as the mechatronics needed to transport the imaging plates and scan them. The video below also shows experiments with the PM tube, which when coupled with a block of scintillating plastic worked as a great radiation detector.
Ask any electronics hobbyist or professional what the simplest building blocks of electronic circuits are, and they’ll undoubtedly say resistors, capacitors, and inductors. Ask a mechanically-inclined person the same question about their field and the answer will probably be less straightforward. Springs would make the list for sure, but then… hmm. Maybe gears? 80/20 aluminum extrusions?
As it turns out, there are a handful of fundamental building blocks in the mechanisms world, and they’re functionally very similar, and mathematically identical, to the Big Three found in electrical engineering.
Before we look at the components themselves, let’s step back a moment and think about voltage and current. Voltage is a potential difference between two points in a circuit, sometimes called electromotive force (EMF). It turns out that EMF is an apt term for it, because it is roughly analogous to, well, force. Voltage describes how “hard” electrons are being “pushed” in a circuit. In much the same vein, current describes the rate of electric charge flow. Continue reading “Building Blocks: Relating Mechanical Elements To Electronic Components”→
You sure do learn a lot when life suddenly makes it impossible to go into the office and asks that you instead do the same work remotely. Sure, there are the obvious challenges like needing a device to do the work on and an internet connection that’s not going to melt down when family or roommates are trying to Zoom at the same time as you one-on-one with the boss. But there’s way more to it. The Refresh Work-From-Home Life challenge takes this on as the next phase of the Hackaday Prize gets under way this morning.
If the global pandemic caused you to find yourself working from home, I’m sure it’s been quite a ride. Maybe you learned what your spine feels like after hunching over a MacBook in bed for 40 hours. Others discovered that the commute had been silently serving as a power-down sequence for your “work brain” — without it you never stopped thinking about, or more likely worrying about, work. And without that change in venue, it’s far too easy to feel like you were now living at work. So let’s invent the things that can make us productive from home while maintaining physical health and preserving our sanity.
Ten entries in this challenge will be awarded with $500 and ushered into the final round where the grand prize of $25,000 and four other top prizes await. What kind of things are we looking for? The best ideas are the ones we haven’t had yet, but I can spitball a bit to get things rolling.
Furniture and other infrastructure can be a real sore-spot when not a good fit. We’d love to see your design that uses a single sheet of plywood (I know, those cost a bazillion dollars these days but just go with it) to build an adjustable workspace that fits your chair height and needs. Bonus points for one that folds away at quitting time to reassure you that work is done!
Office interruptions from co-works sometimes feel like a distraction. But without them you might not get your body moving for hours on end… not good for you! Design an assistant that watches for your poor sedentary habits and sasses you until you take some time to stretch your old bones. Or show off the gadgets that make living the digital nomad life easier like the awesome document camera hacks we saw from teachers when classrooms were closed last year.
Show off your proof of concept by starting a project page on Hackaday.io and using the dropdown in the left sidebar to enter it into the 2021 Hackaday Prize. You can continue to update it until judging begins at the end of July.
We’re already living in the future. Working or learning remotely is a big part of that. Let’s bend our homes and our habits to find a better way to do it!