It is tempting to think of analogue and digital domains as entirely distinct, never to touch each other except like a cold war Checkpoint Charlie, through the medium of an ADC or DAC. In reality there are plenty of analogue effects upon digital circuitry which designers must be aware of, but there is one field in which the analogue and the digital are intricately meshed. Switch mode power supplies use digital techniques to exploit the analogue properties of components such as inductors and capacitors, and can be astoundingly clever in the way they do this to extract the last fraction of a percent efficiency from their conversion. Thus their design can be something of a Dark Art, so it’s always interesting to have a good read explaining some of the intricacies. [James Wilson] has built a flyback step-up converter to power Nixie tubes, and his write-up follows the whole process in great depth.
This type of converter seems at first glance to be a simple step-up design with a transformer that has a primary and secondary, where in fact it relies on the collapse in magnetic field during the off period of its duty cycle to provide a spike in voltage and thus a step-up beyond that you’d expect from the transformer alone. The write-up takes us through all this starting from a theoretical perspective, and then goes further into the realm of component selection and the effects of component properties on the waveforms involved. If you have ever battled ringing in a switch mode power supply you may recognise some of this.
If this field interests you, then there is probably no better place to send you for a start than Jim Williams’ 1987 app note 25 for Linear Technology: “Switching Regulators for Poets“.
Imagine if you will that you are enthroned upon the porcelain, minding your own business while doing your business. You’re catching up on Hackaday on your phone – c’mon, admit it – when a whir and a buzz comes from behind you. You sit up in alarm, whereupon your lower back suddenly feels as if someone is scrubbing it with a steel wool pad. Then the real pain sets in as super-hot plasma lances into your skin, the smell of burning flesh fills the bathroom, and you crack your head on the towel bar trying to escape this torture chamber in a panic.
Sound good? Then [Vije Miller]’s plasma-powered toilet air freshener is a must-build for you. We’re not entirely sure where this was going, but the name of the project seems to indicate a desire to, ahem, clear the air near your derrière with the power of ions. While that might work – we’ve recently seen an electrostatic precipitator for 3D-printer fumes – the implementation here is a bit sketchy. The ball of steel wool? It was possibly intended as a way to disperse the ions, but it served as nothing more than fuel when touched by the plasma. The Contact-esque gimballed rings? Not a clue what they’re for, but they look cool. And hats off to [Vije] for the intricate 3D-printed parts, the geartrain and linkages, and the DIY slip rings.
It’s basically a lightsaber. Except smaller. And with an invisible blade. And cold to the touch. But other than that, this homebrew cold plasma torch (YouTube, embedded below) is just like the Jedi’s choice in elegant weaponry.
Perhaps we shouldn’t kid [Justin] given how hard he worked on this project – seventeen prototypes before hitting on the version seen in the video below – but he himself notes the underwhelming appearance of the torch without the benefit of long-exposure photography. That doesn’t detract from how cool this build is, pun intended. As [Justin] explains, cold plasma or non-equilibrium plasma is an ionized stream of gas where the electron temperature is much hotter than the temperature of the heavier, more thermally conductive species in the stream. It’s pretty common stuff, seen commercially in everything from mercury vapor lamps to microbial sterilization.
It’s the latter use that piqued [Justin]’s interest and resulted in a solid year of prototyping before dialing in a design using a flyback transformer to delivery the high voltage to a stream of argon flowing inside a capillary tube. The quartz tube acts as a dielectric that keeps electrons from escaping and allows argon to be ionized and wafted gently from the tube before it can reach thermal equilibrium. The result is a faint blue glowing flame that’s barely above room temperature but still has all the reactive properties of a plasma. The video shows all the details of construction and shows the torch in action.
Hats off to [Justin] for sticking with a difficult build and coming through it with an interesting and useful device. We’ve no doubt he’ll put it to good use in his DIY biohacking lab in the coming months.
[Tony] built a high-efficiency power supply for Nixie tube projects. But that’s not what this post is about, really.
As you read through [Tony]’s extremely detailed post on Hackaday.io, you’ll be reading through an object lesson in electronic design that covers the entire process, from the initial concept – a really nice, reliable 170 V power supply for Nixie tubes – right through to getting the board manufactured and setting up a Tindie store to sell them.
[Tony] saw the need for a solid, well-made high-voltage supply, so it delved into data sheets and found a design that would work – as he points out, no need to reinvent the wheel. He built and tested a prototype, made a few tweaks, then took PCBWay up on their offer to stuff 10 boards for a mere $88. There were some gotchas to work around, but he got enough units to test before deciding to ramp up to production.
Things got interesting there; ordering full reels of parts like flyback transformers turned out to be really important and not that easy, and the ongoing trade war between China and the US resulted in unexpected cost increases. But FedEx snafus notwithstanding, the process of getting a 200-unit production run built and shipped seemed remarkably easy. [Tony] even details his pricing and marketing strategy for the boards, which are available on Tindie and eBay.
We learned a ton from this project, not least being how hard it is for the little guy to make a buck in this space. And still, [Tony]’s excellent documentation makes the process seem approachable enough to be attractive, if only we had a decent idea for a widget.
We’ve all had the heartbreak of ordering something online, only to have it arrive in less than mint condition. Such are the risks of plying the global marketplace, only more so for used gear, which seems to be a special target for the wrath of sadistic custom agents and package handlers all along the supply chain.
This cruel fate befell a vintage Vectrex game console ordered by [Senile Data Systems]; the case was cracked and the CRT was an imploded mass of shards. Disappointing, to say the least, but not fatal, as he was able to make a working console from the remains of the Vectrex and an old IBM monitor. The Google translation is a little rough, but from what we can gather, the Vectrex, a vector-graphics console from the early 80s with such hits as MineStorm, Star Castle, and Clean Sweep, was in decent shape apart from the CRT. So with an old IBM 5151 green phosphor monitor, complete with a burned-in menu bar, was recruited to stand in for the damaged components. The Vectrex guts, including the long-gone CRT’s deflection yoke assembly, were transplanted to the new case. A little room was made for the original game cartridges, a new controller was fashioned from a Nintendo candy tin, and pretty soon those classic games were streaking and smearing across the long-persistence phosphors. We have to admit the video below looks pretty trippy.
There are times when you make the effort to do a superlative job in the construction of an electronic project. You select the components carefully, design the perfect printed circuit board, and wait for all the pieces to come together as they come in the mail one by one. You then build it with tender care and attention, printing solder paste and placing components by hand with a fastidious attention to detail. There follows an anxious wait by the reflow oven as mysterious clouds of smoke waft towards the smoke detector, before you remove your batch of perfect boards and wait for them to cool.
Alternatively, there are other times when you want the device but you’re too impatient to wait, and anyway you’ve only got half of the components and a pile of junk. So you hack something a bit nasty together on the copper groundplane of a surplus prototype PCB in an evening with ‘scope and soldering iron. It’s not in any way pretty but it works, so you use it and get on with your life.
When you are a Hackaday writer with some oscilloscope bandwidths to measure, you need a picosecond avalanche pulse generator, and you need one fast. Fortunately they’re a very simple circuit with only one 2N3904 transistor, but the snag is they need a high voltage power supply well over 100 V. So the challenge isn’t making the pulse generator, but making its power supply.
For our pulse generator we lacked the handy Linear Technologies switcher used by the avalanche pulse generator project we were copying. It was time for a bit of back-to-basics flyback supply creation, robbing a surplus ATX PSU for its base drive transformer, high voltage diode and capacitor, and driving it through a CRT line output transistor fed by a two-transistor astable multivibrator. Astoundingly it worked, and with the output voltage adjusted to just over 150V the pulse generator started oscillating as it should.
[Matt] works at a neon sign power supply company. When a vendor error left him with quite a few defective high voltage transformers, he couldn’t bring himself to toss them in the bin. [Matt] was able to fix the transformers well enough to work, and the idea for a high voltage keyboard began to brew. Unfortunately, the original transformers were not up to the task of creating a musical arc. At that point the project had taken on a life of its own. Matt grabbed some higher power transformers and started building.
The keyboard has 25 keys, each connected to an individual high voltage circuit with its own spark gap. The HV circuit is based upon a IR2153D self-oscillating half-bridge driver. (PDF link). The 2153D is modulated by a good old-fashioned 555 timer chip. No micros in this design, folks! The output of the IR2153D switches a pair of N-channel MOSFETS which drive the flyback transformers.
[Matt] created 25 copies of his circuit and built them up on individual PCBs. He assembled everything on a wooden board shaped roughly like a grand piano. The final project looks great – though [Matt] admittedly has no musical ability, so we can’t hear AC/DC flying out of those spark gaps just yet.
If you do want to hear sparks playing music, check out the OneTesla project we saw at MakerFaire NY 2013.