Author: Jenny List

3250 Articles

This Baby ‘Scope Is Within Your Reach

December 29, 2023 by 19 Comments

The modern oscilloscope is truly a marvelous instrument, being a computer with a high-speed analogue front end which can deliver the function of an oscilloscope alongside that of a voltmeter and a frequency counter. They don’t cost much, and having one on your bench gives you an edge unavailable in a previous time. That’s not to dismiss older CRT ‘scopes though, the glow of a phosphor trace has illuminated many a fault finding procedure. These older instruments can even be pretty simple, as [Mircemk] demonstrates with a small home-made example that we have to admit to rather liking.

At its heart is a small 5 cm round CRT tube, with an off-the-shelf buck converter supplying the HT, a neon lamp relaxation oscillator supplying the timebase, and a set of passive components conditioning the signal to the deflection plates. The whole thing runs from 12 V and fits in a neat case. It has one huge flaw in that there is no trigger circuit, and sadly this compromises its usefulness as an instrument. Our understanding of a neon oscillator is a little rusty but we’re guessing the two-terminal neon lamp would have to be replaced by one of the more exotic gas-filled tubes with more electrodes, of which one takes the trigger pulse.

Even without a trigger it’s still a neat device, so take a look at it. Perhaps surprisingly we’ve seen few CRT ‘scopes made from scratch here at Hackaday, but never fear, here’s one used as an audio visualiser.

The Gopher Revival Is Upon Us

December 29, 2023 by 39 Comments

A maxim for anyone writing a web page in the mid 1990s was that it was good practice to bring the whole thing (including graphics) in at around 30 kB in size. It was a time when the protocol still had some pretence of efficient information delivery, when information was self-published, before huge corporations brought everything under their umbrellas.

Recently, this idea of the small web has been experiencing something of a quiet comeback. [Serge Zaitsev]’s essay takes us back to a time before the Internet as we know it was born, and reminds us of a few protocols that have fallen by the wayside. Finger or Gopher, both things we remember from our student days, but neither of which was a match for the browser.

All is not lost though, because the Gemini protocol is a more modern take on minimalist Internet information sharing. It’s something like the web, but intentionally without the layer upon layer of extraneous stuff, and it’s been slowly gathering some steam. Every time we look at its software list it becomes more extensive, and we live in hope that it might catch on for use with internet-connected microcontroller-based computing. The essay is a reminder that the internet doesn’t have to be the web, and doesn’t have to be bloated either.

CoreXY On The Pi Pico

December 28, 2023 by 8 Comments

There are enough off-the-shelf CoreXY mechanisms out there that for the cost of an AliExpress order it’s possible to quickly and cheaply make yourself a plotter. But [Koushani Das], [Mahathi Andavolu] and [Dengyu Tu] are completing their project for Cornell University’s ECE 5730 course, so of course they have designed one from the ground up. Happily for us it seems to be fairly easy to replicate, so you can build one too if it takes your fancy.

The write-up makes for an interesting dive into the nitty-gritty of design, for which we hope they managed to secure a decent grade. The hardware itself seems pretty straightforward as does the pair of stepper controllers and RP2040 they use to run the thing, and their explanation of the math behind the CoreXY coordinate system is genuinely interesting for those of us who’ve never taken the time to consider it.

All the good stuff can be found in a GitHub repository if you’d like to take this further, and meanwhile they’ve also put up a demo video which you can see below the break. We like this little plotter, and we hope others will take its design and run with it.

Want more CoreXY explanation? We’re happy to oblige.

Continue reading “CoreXY On The Pi Pico” →

A High-End Studio Multiplexer Surrenders To An Arduino

December 27, 2023 by 17 Comments

The equipment used in professional radio and TV studios is both extremely high quality and very expensive indeed, and thus out of the reach of an experimenter. Happily as studios are refurbished there’s a steady supply of second-hand equipment which can be surprisingly cheap, but as [Nathan] found out with a Quartz audio router, comes with no control software. What’s to be done with what’s essentially a piece of junk? Remove its brain and replace it with one that can be controlled, of course!

On the PCB alongside a bank of switch matrices is an FPGA which does the heavy lifting. That’s “heavy” in a limited sense, because all it does is handle the chip select lines for the matrices and write data to their registers. This is a task that can be handled by a microcontroller, so in goes an Arduino Nano, which along with a few other board modifications delivers a serial-controlled studio router.

The interesting part for us in this project comes from a look at the date codes on the board, they’re from the early 2000s. This is (roughly) contemporary with the ATmega chip on the Arduino, so we’re curious as to why the designers saw fit to use an FPGA when the microcontrollers of the day were clearly up to the task for much less outlay. We suspect a touch of millennium-era price inflation, but we can’t be sure.

Meanwhile, old broadcast kit has featured here before.

An RC Tank Chassis That’s Not Messing About

December 26, 2023 by 3 Comments

It’s not uncommon to see a tracked robot build on these pages, but it’s fair to say that many of them are somewhat on the small side. That was where [iforce2d] started, but the idea of making a more capable version just wouldn’t go away. Thus, he’s come back and made what looks to be a very promising, fully capable outdoor RC tank chassis, one that, within reason, we think should eventually be able to go anywhere.

For plenty of power, he’s using a pair of hoverboard motors with a chain reduction drive and in turn, a couple of shafts to the tracks. The chassis is a TIG-welded aluminium affair, while the tracks are an early incarnation with machined MDF drive wheels and a homemade tread. The suspension is a work of machined-aluminium art, though, and while there are teething troubles as he takes it for a spin, we can see plenty of potential as its deficiencies are ironed out.  Take a look at it in the video below the break.

If large-size R/C tanks are your thing, we have another for you to look at.

Continue reading “An RC Tank Chassis That’s Not Messing About” →

It’s Switch Mode, But Not As You Know It

December 26, 2023 by 33 Comments

The switch-mode power supply has displaced traditional supplies almost completely over the last few decades, being smaller, lighter, and more efficient. But that’s not to say that it’s a new idea, and on the way to today’s high-frequency devices there have been quite a few steps. An earlier one is the subject of a teardown video from [Thomas Scherrer OZ2CPU], as he takes a look at a 1960s HP power supply with a slightly different approach to regulation for the day. Instead of a linear regulator on its conventional transformer and rectifier circuit, it has a pair of SCRs in the mains supply that chop at mains frequency. It’s a switch mode supply, but not quite as you’re used to.

In fact, these circuits using an SCR or a triac weren’t quite as uncommon as you might expect, and could at one point be found in almost every domestic TV set or light dimmer. Sometimes referred to as “chopper” supplies, they represented a relatively cheap way to derive a regulated DC voltage from an AC mains source in the days before anyone cared too much about RF emissions, and though few were as high quality as the HP shown in the video below, they were pretty reliable.

If older switchers interest you, this is not the first one we’ve shown you from that era.

Continue reading “It’s Switch Mode, But Not As You Know It” →

A Web Server, The Sixteen Bit Way

December 25, 2023 by 12 Comments

If you were to talk about sixteen bit computing in retrocomputing circles, misty-eyed reminiscences of the ST or Amiga would emerge. Both fine platforms, but oddly the elephant in the 16-bit room has become a victim of its own success. DOS, the granddaddy of all PC operating systems, seems oddly overshadowed by its 68000-based competitors in a way it certainly wasn’t back in the day. Perhaps it’s the often-atrocious graphics when cards designed for business graphics were pressed into gaming service, but it’s easy to forget that DOS PCs were the powerhouses of their day. They still pack a punch even in 2023, as [Lunduke] is here to show us by running a DOS web server. Take that, nginx! Continue reading “A Web Server, The Sixteen Bit Way” →