A Sinclair ZX81 Clone Still Has The Power To Fascinate

March 15, 2022 by 26 Comments

The golden age of 8-bit computing brought us pixelated graphics in bright colours, accompanied of course by chiptune music. This aesthetic is strong enough to define a collective image of a generation’s youth, even if the 1980s reality had much more of the tired 1970s leftovers about it.  The truth was that not all popular 8-bit machines had colour, sound, or good graphics, and among these limited-capability machines was Sir Clive Sinclair’s ZX81. With a Z80, 1k of RAM, a membrane keyboard, and not much else, it helped set the stage for the hugely popular ZX Spectrum which followed it. The fun’s not over though, as [Augusto Baffa] demonstrates with his modern recreation of a machine that can switch between the ’81 and its less-popular ZX80 predecessor.

Rather than a Eurocard-sized mainboard and membrane keypad, this clone copies the ZX80 with a full-sized mainboard the front of which carries the keyboard contacts. It also eschews the ULA found in the ’81 for discrete TTL. It’s based upon the venerable Grant Searle design for a homebuilt Sinclair computer, and all of the files for this version can be found in a GitHub repository.

There is a lot to be said for the ZX81 as a model for retrocomputer experimentation, because of its extreme simplicity. It may have been no great shakes in the computing department compared to many of its competitors, but it remains possibly one of the easiest of the bunch whose operation to completely understand. Also we like it for that paltry 1k of memory, teaching kids about memory constraints is a good thing in our book.

We’ve featured the diminutive ZX more than once, including a couple of years ago in our April Fools coverage.

Pedal Powered Power

March 14, 2022 by 19 Comments

When you have a solar-powered web server, where do you go next for a source of power? Instead of lazily mooching off the sun, you can use your muscle with a bike generator. [Ed note: The site is run on an entirely solar-powered server, so if it’s the middle of the night, you might have a better web experience here.]

We’ve covered bicycle generators before, so what’s new? For starters, the accessibility of chargers and batteries has changed significantly. Rather than just charging a phone or putting out a measly 5V, this bike can be integrated into an existing solar PV system and output many voltages. This guide goes over building one with hand tools with great detail.

It starts with a 1950’s vintage exercise bicycle, no hacksaw required. A friction drive connects a generator and makes for an incredibly compact generator/exercise machine. Calculating the correct gear ratio is crucial to getting the 12 volts out at an average pedaling speed. You want your range of voltages to be between 5 and 24 volts. With the help of a control panel provides 5v, 12v, 14.4v, and 220v to power a variety of devices. Boost and buck converters output these voltages (depending on whether the voltage needs to be set for a maximum or a minimum). A potentiometer allows you to dial back the power draw of certain appliances (an electric kettle, for instance), making a workout a tad easier on the human component of the generator.

Another key takeaway from this guide is using a wind charge controller to charge batteries. A solar charge controller will just cut the circuit when the batteries are full. A wind charge controller will increase the load until the motor breaks. Some controllers are also hybrid wind and solar, allowing you to connect a small panel like the one running the webserver this guide is posted on and then charge up the batteries when it has been overcast for a few days in a row.

Cool Mechanism Day: Two-Way To One-Way

March 14, 2022 by 8 Comments

The internal mechanisms that are used in timepieces have always been fascinating to watch, and are often works of art in their own right. You don’t have to live in the Watch Valley in Switzerland to appreciate this art form. The mechanism highlighted here (from Mechanistic on YouTube) is a two-way to one-way geared coupler (video, embedded below) which can be found at the drive spring winding end of a typical mechanical wristwatch.  It is often attached to a heavily eccentrically mounted mass which drives the input gear in either direction, depending upon the motion of the wearer. Just a little regular movement is all that is needed to keep the spring nicely wound, so no forgetting to wind it in the morning hustle!

The idea is beautifully simple; A small sized input gear is driven by the mass, or winder, which drives a larger gear, the centre of which has a one-way clutch, which transmits the torque onwards to the output gear. The input side of the clutch also drives an identical unit, which picks up rotations in the opposite direct, and also drives the same larger output gear. So simple, and watching this super-sized device in operation really gives you an appreciation of how elegant such mechanisms are. Could it be useful in other applications? How about converting wind power to mechanically pump water in remote locations? Let us know your thoughts in the comments down below!

If you want to play with this yourselves, the source is downloadable from cults3d. Do check out some of the author’s other work!

We do like these super-sized mechanism demonstrators around here, like this 3D printed tourbillon, and here’s a little thing about the escapement mechanism that enables all this timekeeping with any accuracy.

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Syringe with diluted nail polish used to fill into cursive "FuzzyLogic" letters extruded into a surface of a 3D-printed block of plastic, as a demonstration.

Brighten Up Your Prints With This Nail Polish Approach

March 14, 2022 by 25 Comments

It’s not enough to 3D-print a part – there’s a myriad of things you can do from there! [FuzzyLogic] shows us his approach of adding inlay labels, icons and text to a 3D print, by extruding them into the print and filling the resulting cavity with nail polish! This makes for colorful and useful prints, as opposed to dull single-color parts we typically end up with.

The devil’s in the details, and [FuzzyLogic] has got the details down to a technique. Nail polish has to be diluted with acetone so that it flows well, and a particular combination of syringe and needle will be your friend here. Of course, don’t forget to factor surface tension in – even with well-diluted nail polish, you cannot make the grooves too thin. A bit more acetone on a q-tip helps in case of any happy little accidents, and a coat of clear acrylic spray paint seals the lettering firmly in place. The five-minute video tells you all about these things and a quite few more, like the basics of extruding text and icons in a typical CAD package, and has a bit of bonus footage to those watching until the end.

Adding markings to our prints is a lovely finishing touch! If you’re looking for more of that, here’s a custom tool-changing printer with a pen attachment making beautiful custom enclosures for the Pocket Operator.

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Hackers Beware: Shenzhen Is Closing

March 14, 2022 by 43 Comments

If you’re among those of us with immediate plans for a PCB or parts order from China, watch out – Shenzhen just recently got put on a week-long lockdown. Factories, non-essential stores and public places are closed, and people are required to spend time at home – for a city that makes hardware thrive, this sounds like a harsh restriction. Work moves to remote where possible, but some PCB fabs and component warehouses might not be at our service for at least a week.

It might be puzzling to hear that the amount of cases resulting in closures is as low as 121, for a city of 12.6 million people. The zero-tolerance policy towards COVID has been highly effective for the city, with regular testing, adhered-to masking requirements and vaccinations – which is how we’ve been free to order any kinds of boards and components we needed throughout the past two years. In fact, 121 cases in one day is an unprecedented number for Shenzhen, and given their track record and swift reaction, it is reasonable to expect the case count dropping back to the regular (under 10 cases per day) levels soon.

Not all manufacturing facilities are located in Shenzhen, either. Despite what certain headlines might have you believe, supply chain shortages aren’t a certainty from here. A lot of the usual suspects like PCBWay and JLCPCB are merely reporting increased lead times as they reallocate resources, and while some projects are delayed for now, a lot of fabs you’d use continue operating with minor delays at most. SeeedStudio has its operations impacted more severely, and your Aliexpress orders might get shipped a bit later than usual – but don’t go around calling this a Chinese New Year v2 just yet. For those who want to keep a closer eye on the situation and numbers, the [Shenzhen Pages] Twitter account provides from-the-ground updates on the situation.

Wondering how your supply chain might be affected? We’ve talked about this way back in February 2020, addressing then-warranted worries that Chinese New Year would grow into a longer disruption than planned due to COVID becoming into a factor to manage. If you’re yet to discover the significance of Shenzhen, books have been written on this marvellous city, where you can build a successful hardware company in a week’s time. We’ve even had a meetup there once!

Header image: Charlie fong, CC BY-SA 4.0.

Cheap Ghostbusters Toy Turned Convincing Prop

March 14, 2022 by 2 Comments

As you might expect, the release of last year’s Ghostbusters: Afterlife has not only lead to renewed interest in the old 1980s toys and tie-in merchandise, but has spawned a whole new generation of blinking plastic gadgets to delight children of all ages. Of course, for folks like us, that means more hardware to hack on.

In a recent post to the official Ghostbusters YouTube channel, professional prop maker [Ben Eadie] shows off some of the tricks of the trade when he takes a $15 USD “PKE Meter” toy from Hasbro and turns it into a screen-quality prop. Even if you’re not looking to get an early start on your Halloween costume, the techniques demonstrated in this video could be easily adapted to other projects. For those whose next ideal home improvement is a fireman’s pole and an ectoplasmic laser-confinement grid, you might want to grab a couple of these toys while they’re still cheap for eventual conversion.

Uncovering the silver makes the piece look worn down.

The biggest takeaway from the video is probably the finishing techniques, as they could be used on any sort of realistic prop build. [Ben] starts by using a cabinet scraper to smooth out the lines on the plastic toy, and any holes are filled with the familiar baking soda and cyanoacrylate glue trick. Once the surfaces have been prepped, all the principle parts are sprayed with an adhesion promoter, followed by a coat of silver, and then the final black color.

This allows him to create a convincing “chipped paint” effect by strategically sanding or scraping through the top coat. Dabbing some toothpaste where you want the device to look worn down before spraying the final coat makes the process even faster, as it will prevent the top coat from sticking to the silver in the first place.

Unfortunately [Ben] doesn’t spend a whole lot of time explaining the electronics side of things, but it doesn’t look like there’s anything too complex going on. All the original gear is stripped, and it gets replaced with a microcontroller which we believe is an Adafruit ItsyBitsy nRF52840 Express. This is connected to two strings of tiny APA102 addressable LEDs which are run down the “wings” (we especially like the 3D printed lenses used to replace the original solid pips), and one that’s used to provide the iconic sine-wave display.

While the last PKE meter build we saw did detect radiation, we have to admit that in terms of looks, this one takes the top spot. Especially when you consider how cheap the thing was. All you need now is a Proton Pack, and you’ll be ready for Halloween.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Really Tall Keycaps

March 14, 2022 by 5 Comments

About a month ago, [Unexpected Maker] finished their TinyS3, an ESP32-S3 development board. Since the chip supports both true USB and Bluetooth, [deʃhipu] wondered how well it would work in a keyboard.

Thus, the Vegemite Sandwich was made, perhaps while [deʃhipu] was dreaming of traveling in a fried-out Kombi. But really, it was named so because [Unexpected Maker] hails from Australia.

This is [deʃhipu]’s first time using switch sockets, which is (as far as we know) the only choice when it comes to hot-swappable Kailh chocs. We’ll be watching this one with hungry eyes.

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