A Redesigned ZX Spectrum Desktop Computer That Works Surprisingly Well

October 17, 2021 by 20 Comments

Retrocomputer enthusiasts will quite often be found pondering the great what ifs of their hobby. What if Commodore had had a half-way decent marketing division is a popular one, but the notoriously penny-pinching ways of Sinclair Research are also a plentiful source. What if Sinclair had won the competition for a computer in UK schools, not only the first time around when Acorn’s BBC Micro scooped the prize, but also what if they’d entered the fray once more in 1983 when there was another chance? [10p6] investigates this possibility, and comes up with a Spectrum desktop computer that you can see in the video below the break.

The first two-thirds of the video is devoted to renders which, while pretty to look at, offer nothing of substance. In the later part though we see a build, putting a Spectrum 48k board, Interface 1, and two Microdrives in a slimline case along with a power supply. Meanwhile a ZX rubber keyboard is mounted stand-alone on the end of a cable. It’s a computer that we know would have been an object of desire for many kids back in the day, and we agree with the video that it could have been integrated onto one board without the need for a separate Interface 1. We feel it’s inevitable though that Sinclair’s cost-cutting would have caused something to go astray and there would certainly have been only one Microdrive, even though we like that separate keyboard a lot.

They claim that the STLs will be available from a Facebook group, however unless you happen to have a set of Microdrives and an Interface 1 to go with your Spectrum that you’re prepared to butcher for the project we’re guessing that the chief interest lies in watching it unfold and that some of the ideas might translate to other platforms. Meanwhile if you’re interested in the Microdrive, we did a teardown on them last year.

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Electronic Covid Test Tear Down Shows Frustrating Example Of 1-Time-Use Waste

October 17, 2021 by 68 Comments

The latest video from [TheSignalPath] is a result of his purchase of a home COVID-19 test. He found an electronic version that connects to your cell phone and displays the results on the phone. The device is an antigen test and, internally, works like the home tests that show the results using lines similar to a pregnancy test. So, somehow, the phone version reads the lines and communicates with the phone. But how? That’s the point of the video, which you can see below.

In a traditional test, there’s a control line that has to appear to show that the test was done correctly. Then a line under that indicates detection of the virus. The circuit board inside the electronic test has a plastic unit onboard that contains a similar strip and has optical sensors for both the reference line and the detection line. Since it is essentially an optical device — there are some lenses in the strip assembly that look like they are detecting the dye as it moves through the strip with LEDs onboard to shed light on the situation.

Under the microscope, the CPU is a typical Bluetooth-capable ARM chip from Nordic. The board did power up, but the device is made to only operate once because of the test strip. The video notes — and we agree — it seems wasteful to create an entire Bluetooth-enabled microcontroller board with optical components just to read a strip one time that is pretty easy to read to start with. We’ll stick with the simple test strip. Still, it is interesting to see the insides.

If you want to read more about antigen tests, we covered that. We also talked about PCR testing.

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PS/2 wireless dongle

The Wireless PS/2 Keyboard That Never Was

October 16, 2021 by 11 Comments

The PS/2-style port was once about as ubiquitous on PCs as USB connectors are today, and more than a few of us accumulated a fair collection of keyboards and mice that sported the 6-pin mini-DIN plug. They’re not nearly as common today, but when you need one, you need one, so if your stockpile of PS/2 keyboards has dwindled to nothing, you might want to look at rolling your own PS/2 remote keyboard dongle.

That backstory on [Remy Sharp]’s build starts with his acquisition of a neptUNO, a 160€ FPGA retrocomputer that gives you access to just about every Z80 and 6502 computer of yesteryear. While the box supports USB keyboards, [Remy] had trouble getting one to work. So out came a Wemos D1 Mini, which was wired up to a stub of PS/2 cable. The microcontroller is powered by the PS/2 port, and connects to the WiFi network on boot-up and starts a WebSocket server. It also served up a page of HTML, which lets him connect with any device and send keystrokes to the neptUNO. He also added a couple of hardware buttons to the dongle, to access menus on the neptUNO directly. The video below shows it in action.

Perhaps unsurprisingly, [Remy] says he took inspiration for this build from [Ben Eater]’s excellent PS/2 deep dive. We’d like to think he saw that here first, but either way, it’s a valuable reference on how keyboards used to work.

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Jet tools air scrubber

It’s A Hack: Air Scrubber Controlled Using The Room Lighting

October 16, 2021 by 8 Comments

Some products just seem to be designed to be annoying. [hardmar] discovered the air filtration system installed in his son’s basement woodshop was orientated for the best airflow, but rather poorly positioned to actually turning the thing on and off. For some reason the unit has its single line-of-sight IR receiver on one side, which when mounted in some positions, forces the user to be the completely wrong position to use the supplied remote.

We find it a little unhelpful sometimes that devices specifically designed to be mounted with varying orientations don’t come fitted with IR receivers in different locations to ensure good controllability. It would get annoying really fast to have to contort oneself into some specific position just to turn something on, and some people just might not bother at all.

Proper control of dust is paramount for continued good health, and essential in any workspace or shared area. When you work wood, it produces a lot of dust. It cannot be avoided and gets into everything, your lungs included. PPE is not enough.  Even in your own shop you still really should manage dust production as best you can. Options are varied from centralised extraction, per machine solutions, and often augmented with air scrubbers mounted on the ceiling to grab those fine particulates.

Instead of solving the IR placement issue, [hardmar] wanted to have the unit tied to the lighting system so that it would power on as soon as someone turned on the appropriate light and would then stay on for a fixed amount of time after the user left in order to continue scrubbing the air some more. His simple hack was to first record and analyse the IR protocol used by the remote, and program an Arduino to be able to send it on/off commands. Next, he hooked up a phototransistor aimed at the light, in order to provide the necessary ‘user present’ trigger to tell the Arduino when to activate the scrubber. Super simple and effective. We love this non-invasive approach of adapting off-the-shelf equipment to our specific requirements, without even showing it a screwdriver.

As [hardmar] admits, the hack is not elegantly implemented, it’s just enough to make it work, and that’s just fine, sometimes you just have a job to do and no more.

The Simplest Way To Spot 2.4GHz RF

October 16, 2021 by 24 Comments

When the cool kids are showing off their SDRs it’s easy to forget that a radio receiver can be very simple indeed. The crystal set is one of the earliest forms of radio receiver, a tuned circuit and a diode that would pick up those AM broadcast stations no problem. But lest you imagine that these receivers can only pick up those low frequencies, here’s Hackaday alum [Ted Yapo] with a handy 2.4GHz receiver that picks up strong WiFi and microwave oven leakage.

It’s about as simple as it gets, an LED with a UHF diode in reverse across it. The clever part lies in the wire leads, which are cut to resonate as a dipole at 2.4 GHz. The resulting RF voltage is rectified by the UHF diode, leaving enough DC for the LED to flash. If you are wondering why the LED alone couldn’t do the job as a rectifier you would of course be on to something, however its much worse high frequency performance would make it not up to the job at this frequency.

The glory days of analogue broadcasting may now be in the past, but it’s still possible to have fun with a more conventional crystal radio. If you are adventurous, you can even make one that works for the FM, band too.

Fail Of The Week: Magnetic Levitation

October 16, 2021 by 26 Comments

We are big fans of the little desktop magnetic levitation setups that float a small object on a magnet. As [3D Printed Life] points out, they look like magic. He was surprised that the commercial units use analog electronics. He decided to build a digital version but didn’t know what he was getting into. He details his journey in the video you can see below.

Along with a custom control board, he decided to wind his own electromagnets. After finding that tedious he built a simple coil winder to automate some of the work.

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Several frames from Bad Apple

PineTime Smartwatch And Good Code Play Bad Apple

October 16, 2021 by 11 Comments

PineTime is the open smartwatch from our friends at Pine64. [TT-392] wanted to prove the hardware can play a full-motion music video, and they are correct, to a point. When you watch the video below, you should notice the monochromatic animation maintaining a healthy framerate, and there lies all the hard work. Without any modifications, video would top out at approximately eight frames per second.

To convert an MP4, you need to break it down into images, which will strip out the sound. Next, you load them into the Linux-only video processor, which looks for clusters of pixels that need changing and ignores the static ones. Relevant pixel selection takes some of the load off the data running to the display and boosts the fps since you don’t waste time reminding it that a block of black pixels should stay the way they are. Lastly, the process will compress everything to fit it into the watch’s onboard memory. Even though it is a few minutes of black and white pictures, compiling can take a couple of hours.

You will need access to the watch’s innards, so hopefully, you have the developer kit or don’t mind cracking the seal. Who are we kidding, you aren’t here for intact warranties. The video resides in the flash chip and you have to transfer blocks one at a time. Bad Apple needs fourteen, so you may want to practice on a shorter video. Lastly, the core memory needs some updating to play correctly. Now you can sit back and…watch.

Pine64 had a rough start with the single-board computers, but they’re earning our trust with things like soldering irons and Google-less Linux mobile phones.

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