Tactical Build Makes Machining Splined Shaft A Snap

May 5, 2023 by Dan Maloney 9 Comments

Quick, what’s 360 divided by 23? It’s easy enough to get the answer, of course, but if you need to machine a feature every 15.652 degrees around a shaft, how exactly would you accomplish that? There are a number of ways, but they all involve some degree of machining wizardry. Or, you can just make the problem go away with a little automation.

The story behind [Tony Goacher]’s Rotary Table Buddy begins with some ATV tracks he got off AliExpress. His idea is to build a specialty electric vehicle for next year’s EMF Camp. The tracks require a splined shaft to drive them, which would need to be custom-made on a milling machine. A rotary table with a dividing plate — not as fancy as this one, of course –is usually the answer, but [Tony] was a little worried about getting everything set up correctly, so he embarked on a tactical automation solution to the problem.

An RP2040 provided the brains of the project, while a NEMA 23 stepper provides the brawn. [Tony] whipped up a quick PCB and 3D printed a case for the microcontroller, a stepper driver, an LCD display, and a few buttons. He 3D printed an adapter and a shaft coupler to mount the stepper motor to a rotary table. From there it was just a matter of coming up with a bit of code to run everything.

There’s a brief video in [Tony]’s blog post that shows Rotary Table Buddy in action, indexing to the next position after cutting one of the 23 splines. He says it took about ten minutes to cut each spline using this setup, which probably makes to total cutting time far less than the amount of time invested in the tool. But that’s hardly the point, and besides, now he’s set up for all kinds of machining operations in the future.

And we sure hope we hear about the EMF Camp build, too.

The Cheap And Available Microwave Playground

April 28, 2023 by Jenny List 11 Comments

There’s something of a mystique about RF construction at the higher frequencies, it’s seen as a Black Art only practiced by elite wizards. In fact, UHF and microwave RF circuitry is surprisingly simple and easy to understand, and given the ready availability of low-noise block downconverters (LNBs) for satellite TV reception there’s even a handy source of devices to experiment on. It’s a subject on which [Polprog] has brought together a handy guide.

A modern LNB has some logic for selecting one of a pair of local oscillators and to use vertical or horizontal polarization, but remains otherwise a very simple device. There’s an oscillator, a mixer, and an RF amplifier, each of which uses microwave transistors that can with a little care be repurposed. The page demonstrates a simple transmitter, but it’s possible to create more powerful devices by using the amplifier stage “in reverse”.

Meanwhile the oscillator can be moved by loading the dielectric resonators with PVC sleeving, and the stripline filters can even be modified with a fine eye for soldering and some thin wire. Keep an eye out in thrift stores and yard sales for old satellite dishes, and you can give it a go yourself. It’s a modern equivalent of the UHF tuner hacking enjoyed by a previous generation.

Op Amp Challenge: What’s Your Monitor’s Delay?

April 27, 2023 by Jenny List 12 Comments

In the days of CRT displays, the precise synchronization between source and display meant that the time between a video line appearing at the input and the dot writing it to the screen was constant, and very small. Today’s display technologies deliver unimaginable resolutions compared to the TV your family had in the 1970s, but they do so at the expense of all their signal processing imposing a much longer delay before a frame is displayed. This can become an issue for gamers, but also with normal viewing, because in some circumstances the delay can be long enough for it to be audible in a disconnect between film and soundtrack. It’s something [Mike Kibbel] has addressed with his video input delay meter, and it makes for a very interesting project.

At its heart is an FPGA, and in the video below the break he goes into great detail about its programming. It both generates a DVI output to drive the monitor and performs the measurement. The analog to digital converter side of the circuit is interesting, he has a photodiode and an op-amp driving a comparator to form a simple 1-bit converter. He takes us through the design process in detail, with such useful little gems as the small amount of hysteresis applied to the comparator.

There are probably many ways this project could have been implemented, but this one is both technically elegant and extremely well documented. Definitely worth a look!

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VCF East 2023: Adrian Black On Keeping Retro Alive

April 26, 2023 by Tom Nardi 3 Comments

While roaming the halls of Vintage Computer Festival East 2023, we ran into [Adrian Black], who was eager to talk about the importance of classic computing in his own life and how his experience hosting the YouTube channel Adrian’s Digital Basement has impacted him these last few years.

On his channel, [Adrian] spends most of his time repairing vintage systems or exploring little-known aspects of hardware from the early days of desktop computing. His exploits have brought him to the pages of Hackaday in the past, most recently just last month, when we covered his work to add an RGB interface to a mid-1990s Sony Trinitron CRT display. But in talking to him, you quickly realize he’d be working on the very same projects whether the camera was rolling or not. He’s not out to game the YouTube algorithm; he’s just having a good time in the basement poking around with the sort of old gear that at one time would have been completely out of reach.

In fact, it’s this sense of nostalgia that [Adrian] believes is responsible not just for the growing popularity of his channel but for the retrocomputing community as a whole. For many who grew up with these machines, they were far too expensive or complex to ever crack open (literally and figuratively) when they were new. Now, decades later, people like himself finally find themselves able to buy and enjoy these once-coveted objects.

Critically, they now also have the skills to do them justice, not to mention access to a worldwide community of like-minded folks who are still producing hardware and software that can be used with these classic machines. For those of a certain age, it’s literally a dream come true.

[Adrian] was just one of the retro aficionados we got a chance to talk to during VCF East 2023. We already brought you the chat we had with [Andy Geppert] about magnetic core memory and his Core64 device, but there’s plenty more to come. Stay tuned.

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Hackaday Prize 2023: The Assistive Tech Challenge Starts Now

April 26, 2023 by Tom Nardi 1 Comment

We’d all love to change the world and make it a better place, but let’s be honest…that’s a pretty tall order. Even the best of ideas, implemented perfectly, can only do so much globally. But that doesn’t mean the individual can’t make a difference — you just need to think on a different scale. If improving everyone’s life is a bit out of reach, why not settle for a smaller group? Or perhaps even just one person?

That’s precisely what we’re looking for in the Assistive Tech Challenge of the 2023 Hackaday Prize. In this Challenge, we’re asking the community to come up with ideas to help those with disabilities live fuller and more comfortable lives.

Whether you help develop an improved prosthesis that could benefit thousands, or design a bespoke communication device that gives a voice to just a single individual, it’s hard to imagine a more noble way to put your skills and knowledge to use.

Looking to lend a hand? You’ve got from now until May 30th to enter your Assistive Tech project. It doesn’t matter what kind of impairment it focuses on — so long as it helps somebody work, learn, or play, it’s fair game to us.

The ten finalists for this Challenge will be announced around June 12th, but you’ll have to wait until Hackaday Supercon in November to find out which projects take home their share of the more than $100,000 in cash prizes graciously provided by sponsors Digi-Key and SupplyFrame.

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Vectrex Light Pen Works Without A Raster

April 26, 2023 by Jenny List 6 Comments

Sometimes the simplest of projects end up revealing the most interesting of things, as for example is the case with [Ryo Mukai]’s light pen for the Vectrex console. It’s an extremely simple device using an integrated light sensor with built-in Schmitt trigger, but for us the magic isn’t in the pen itself but in discovering how it worked with the Vectrex’s vector graphics.

Light pens were a popular accessory in the 8-bit computing days, offering a relatively inexpensive pointing device that gave your micro an even more futuristic feel. On most computers that used a raster-scanning TV display they simply picked up the flying dot on the screen as it passed the end of the pen, but the Vectrex with its display not scanning all of the screen at once needed a different approach.

This piqued our interest, and the answer to how it was done came from PlayVectrex. There was a target X on the screen which could be picked up with the pen, and when picked up it would surround itself with a circle. Crossing the dot as it flew round the circle would tell the console where the pen was, and the position would move to fit. For those of us who only saw a Vectrex in a shop window back in the day, mystery solved! We’ve placed a video showing the process below the break.

This isn’t the first light pen we’ve seen, they can even be connected to modern computers, too.

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OSI Superboard II Replicated

April 24, 2023 by Al Williams 6 Comments

While our modern computer can easily emulate a lot of different old machines, there is something about having replica hardware that is even better. Not as nice as having the real thing, in some ways, although you don’t have to worry about wear and tear on a replica, either. [Jeff Tranter] has built a kit replica of an Ohio Scientific Superboard II, and it looks great, as you can see in the video below.

This was an inexpensive all-in-one 6502 computer with a keyboard and provision for TV or monitor output. If you had a 5V power supply, a cassette deck, and a TV you were in business for less money than most of the comparable alternatives. In fact, [Jeff] has the canceled check where his parents paid $486 Canadian for one in 1981. That was his introduction to computing, and we’d say that was a reasonable investment on the part of his parents.

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