Hackaday Links: October 6, 2019

October 6, 2019 by Dan Maloney 15 Comments

“If you or someone you love has been exposed to questionable quality electrolytic capacitors, you could be entitled to financial compensation.” Perhaps that’s not exactly the pitch behind this class action lawsuit against capacitor manufacturers, but it might as well be. The suit claims that the defendants, a group of capacitor manufacturers that includes Nichicon, Matsuo, ELNA, and Panasonic, “engaged in an unlawful conspiracy to fix, raise, maintain, or stabilize the prices of Capacitors.” Translation: if you bought capacitors between 2002 and 2014 from a distributor, you paid too much for them. The suit aims to recover a bunch of money from the defendants and divide it up between all the class members, so make sure you go back through all your receipts from Mouser and DigiKey over the last 17 years so you can file a claim that could be worth several dozen cents.

When are people going to learn that posting pictures of their illegal activities online is an Official Bad Idea? One SpaceX fan earned a night in jail after posting selfies he took with Starhopper, the SpaceX test article currently residing at Elon Musk’s would-be spaceport at Boca Chica, Texas. JB Wagoner, a SpaceX super-fan, made the pilgrimage from California to Texas — in his Tesla of course — to see the recent Starship Mark 1 unveiling, and decided to take a side trip to see the Starhopper. He parked at a beach, climbed a dune, and was able to walk right up to Starhopper and go selfie-crazy. After posting the pictures on Facebook, he was arrested, interviewed by Homeland Security, charged with criminal trespass, and thrown in a cell overnight. Wagoner has since been bonded out, but the charges might not stick, since Texas trespassing law requires clear signage or verbal notification of trespass, neither of which Wagoner encountered. SpaceX had even let the fence between the beach and the Starhopper collapse, so Wagoner seems to have had no way of knowing he was trespassing. Still, posting the pictures online was probably asking for trouble.

As satire and dark comedy, the 1987 cyberpunk classic RoboCop can’t be beat. But it also managed to accurately foreshadow a lot of what was to come in the world in terms of technology. No, we don’t have cyborg law enforcement — yet — but we do have something predicted by one throwaway scene: robotic realtors. In the movie, kiosks were set up around Murphy’s old house to extol the various virtues of living there, which ended up triggering the cyborg and starting the film’s climactic rampage. The real-life robotic realtor is a little more flexible, more like a telepresence robot — described aptly as “a Segway with an iPad on top.” The robotic realtor is not autonomous; it only lets a remote realtor interact with potential homebuyers without having to travel to multiple homes. It seems a little gimmicky to us, but the robots are reported to have made 25 sales in their first year on the job.

We’ve been seeing a lot of cheap resin printers these days, enough to make us want to jump into the market and start playing with them. But the cheap ones are all cheap for the same reason — they’re so dang small! They all use LCD screens from phones to mask off the UV light used to cure the resin, and the resulting print volume is tiny. Clem Mayer from MayerMakes has bigger ideas, though: he wants to make a giant resin printer using an LCD monitor as the mask. It’s not as simple as using a bigger screen, though; the film used between the screen and the resin, a fluoropolymer film called FEP, gets deformed when used on larger screens. So Clem is looking at a new built-plate interface that floats the resin on a layer of denser, immiscible liquid. It’s an interesting idea that is still clearly in the proof-of-concept phase, but we look forward to seeing what progress Clem makes.

[Mr. Carlson] Fixes A Fridge

September 21, 2019 by Dan Maloney 28 Comments

A dead refrigerator is an occurrence determined to frustrate any homeowner. First there’s the discovery of hundreds of dollars in spoiled food, and then the cost of a repair call and the delay of the inevitable wait for parts. It’s clear to see why a hacker like [Mr. Carlson] would seek another way.

Now, normally a fridge repair video would by unlikely fodder for a Hackaday article. After all, there’s generally not much to a fridge, and even with the newer microprocessor-controlled units, diagnosis and repair are usually at the board-level. But [Mr. Carlson] has had this fridge since 2007, and he’s got some history with it. An earlier failure was caused by the incandescent interior lights welding relay contacts closed thanks to huge inrush currents when starting the cold filaments. That left the light on all the time, heating the interior. His fix was a custom solid-state relay using zero-crossing opto-isolators to turn the bulbs on or off only when the AC power was at a minimum.

That repair kept things going for years, but when the latest issue occurred, [Mr. Carlson] took a different tack. He assumed that a board that has been powered 24-7 for the last twelve years is likely to have a bad capacitor or two. He replaced all the caps, threw in a few new relays to be on the safe side, and powered the fridge back up. It whirred back to life, ready for another decade or so of service.

Kudos to [Mr. Carlson] for his great repair tips and his refusal to surrender. The same thing happened when his solder sucker started to give up the ghost and he fixed it by adding a variable-frequency drive.

Continue reading “[Mr. Carlson] Fixes A Fridge” →

Ask Hackaday: Experiences With Capacitor Failure

April 12, 2019 by Brian Benchoff 117 Comments

Regular readers of Hackaday are intimately knowledgeable about old electronics, and whether it’s about that old oscilloscope sitting in the pile of other oscilloscopes, or the very rare vintage computer made in a Soviet bloc country, someone somewhere knows how to fix it. One of the biggest problems with these old electronics are capacitors. If it isn’t the battery that’s gone dead and leaked all over, it’s the caps that are either out of spec or have already exploded.

These machines can be brought back from the dead, and in recent months and years we’ve seen an uptick in the number of restomods hitting the Hackaday tip line. If you have a soldering iron and the patience to do so, any machine can be brought back from the grave.

Continue reading “Ask Hackaday: Experiences With Capacitor Failure” →

Components Cut In Half Reveal Their Inner Beauty

April 2, 2019 by Dan Maloney 7 Comments

We rarely take a moment to consider the beauty of the components we use in electronic designs. Too often they are simply commodities, bought in bulk on reels or in bags, stashed in a drawer until they’re needed, and then unceremoniously soldered to a board. Granted, little scraps of black plastic with silver leads don’t exactly deserve paeans sung to their great beauty – at least not until you cut them in half to reveal the beauty within.

We’ve seen a little of what [Tube Time] has accomplished here; recall this lapped-down surface-mount inductor that [electronupdate] did a while back. The current work is more extensive and probably somewhat easier to accomplish because [TubeTime] focused mainly on larger through-hole components such as resistors and capacitors. It’s not clear how the sections were created, but it is clear that extreme care was taken to lap down the components with enough precision that the inner structures are clearly visible, and indeed, carefully enough that some, most notably the LED, still actually work. For our money, though, the best looking cross-sections are the capacitors, especially the electrolytic, for which [Tube Time] thoughtfully provides both radial and axial sections. The little inductor is pretty cool too. Some of the component diagrams are annotated, too, which makes for fascinating reading.

Honestly, we could look at stuff like this all day.

Thanks to [Stuart Rogers] for the tip.

Tesla Eyes Ultracapacitor Future With Maxwell Acquisition

February 4, 2019 by Brian Benchoff 29 Comments

As reported by Bloomberg, Tesla has acquired the innovative energy storage company Maxwell Technologies for $218 Million. The move is a direct departure from Tesla’s current energy storage requirements; instead of relying on lithium battery technology, this acquisition could signal a change to capacitor technology.

The key selling point of capacitors, either of the super- or ultra- variety, is the much shorter charge and discharge rates. Where a supercapacitor can be used to weld metal by simply shorting the terminals (don’t do that, by the way), battery technology hasn’t yet caught up. You can only charge batteries at a specific rate, and you can only discharge them at a specific rate. The acquisition of an ultracapacitor manufacturer opens the possibility of these powerhouses finding their way into electric vehicles.

While there is a single problem with super- and ultra-capacitors — the sheer volume and the fact that a module of ultracaps will hold much less energy than a module of batteries of the same size — the best guess is that Tesla won’t be replacing all their batteries with caps in the short-term. Analysts think that future Teslas may feature a ‘co-battery’ of sorts, allowing for fast charging and discharging through a series of ultracapacitors, with the main energy storage in the car still being the lithium battery modules. This will be especially useful for regenerative braking, as slowing down a three thousand pound vehicle produces a lot of energy, and Tesla’s current battery technology can’t soak all of it up.

Energy Sipping Neodymium Sphere Keeps On Spinning

November 23, 2018 by Tom Nardi 16 Comments

At this point we’re sure you are aware, but around these parts we don’t deduct points for projects which we can’t immediately see a practical application for. We don’t make it our business to say what is and isn’t worth your time as an individual hacker. If you got a kick out of it, great. Learned something? Even better. If you did both of those things and took the time to document it, well that’s precisely the business we’re in.

So when [Science Toolbar] sent in this project which documents the construction of an exceptionally energy efficient spinning neodymium sphere, we knew it was our kind of thing. In the documentation it’s referred to as a motor, though it doesn’t appear to have the torque to do any useful work. But still, if it can spin continuously off of the power provided by a calculator-style photovoltaic cell, it’s still a neat trick.

But how does it work? It starts by cracking open one of those little solar powered toys; the ones that wave or dance around as soon as any light hits the panel in their base. As [Science Toolbar] explains, inside these seemingly magical little gadgets is a capacitor and the classic black epoxy blob that contains an oscillator circuit. A charge is built up in the capacitor and dumped into a coil at roughly 1 Hz, which provides just enough of a push to get the mechanism going.

In the video after the break, [Science Toolbar] demonstrates how you can take those internals and pair it with a much larger coil. Rather than prompting a little sunflower or hula girl to do its thing, the coil in this version provides the motive force for getting the neodymium sphere spinning. To help things along, they’re even using a junk box zero friction magnetic bearing made up of a wood screw and a magnetized screwdriver tip.

It’s an interesting example of how a tiny charge can be built up over time, and with a nice enough enclosure this will make for a pretty cool desk toy. We’ve previously seen teardowns of similar toys, which revealed a surprising amount of complexity inside that little epoxy blob. No word on whether or not the version [Science Toolbar] cannibalized was quite so clever, however.

Continue reading “Energy Sipping Neodymium Sphere Keeps On Spinning” →

DIY Tuning Capacitors From Washers And 3D-Printed Parts

October 25, 2018 by Dan Maloney 34 Comments

The inside of classic radios holds wonders that the sterile chips and SMD components of today’s circuits can’t hold a candle to. Chunky resistors and capacitors, vacuum tubes with cathodes aglow, and seemingly free-form loops of wire forming inductors will all likely make an appearance. But the most fascinating bit of any old radio was connected to the tuning knob: the big variable capacitor with its interdigitating metal plates. Watching one at work, with its plates evenly and finely spaced, is still a joy to behold.

In an attempt to recapture a little of that magic, [Jeremy S. Cook] came up with this home-brew variable tuning capacitor. The frame is built mainly from 3D-printed parts, which supports a shaft made from a common bolt. Plates are fashioned from stainless steel fender washers cut in half; the fixed plates are press-fit into the frame while the rotary plates ride on the shaft. The spacing between the rotary plates is maintained by printed spacers, which also serve to lock the rotor into one solid unit. [Jeremy]’s prototype, for which he provides STL files, can be tuned between about 7 and 15 pF. Check out the build in the video below.

We love the look of this, and we can imagine custom tuning caps would come in handy for certain retro radio builds. The tuning range is a little narrow, but that could be fixed with more plates or closer spacing. That might be a tall order with thick steel washers, but we’ve seen really thin aluminum machined and closely spaced before, so this might be one approach to higher capacitance. Continue reading “DIY Tuning Capacitors From Washers And 3D-Printed Parts” →