Author: Dan Maloney

2993 Articles

New Take On The Camera Obscura Brings Paris Indoors

August 19, 2023 by 13 Comments

We haven’t checked, but we’ll go out on a limb here and say this is the first project we’ve featured with a BOM that includes “an apartment in Paris with a breathtaking view of the Eiffel Tower.” We suppose there are other places in the world where a giant camera obscura like this would work too, but you’ve got to admit that the view is pretty spectacular.

Of course, a camera obscura is really just a dark room — that’s literally what it means in Latin — with a small aperture to admit light from the outside world. This projects an inverted image on the opposite wall, which must have looked absolutely magical to pre-technical people and honestly is still pretty stunning today. Either way, it’s a low-tech way of seeing the world in a different light. [Mathieu Stern] decided his camera obscura would turn the traditional design on its head. Literally — he wanted an upright image. Luckily, he found a supplier that makes special optics for camera obscura that do just that. It looks like the optic uses a Dove prism to invert the image, or in this case to turn it back into an upright image.

The real hack here was finding the perfect place with just the right view of the Eiffel Tower — not at all an easy task in a medieval city where streets go where they will and buildings tend to block the sightlines. [Mathieu] eventually managed to find just the right place. With a little aluminum foil to make the rented room really obscura and some strategically positioned sheets to improve the projection surface, he was able to project some beautiful images of the landmark and surrounding cityscape in a panorama on the apartment walls. The video below has some stills and time-lapse sequences that are pretty breathtaking.

We’ve seen other camera obscura before, including this mobile version which may have made things easier for [Mathieu], at the price of giving up a lot of the charm.

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Hackaday Prize 2023: Over-the-Top Programmable Resistor Looks The Part And Performs

August 18, 2023 by 18 Comments

Every once in a while we get wind of a project that we’re reluctant to write up for the simple reason that it looks too good to be true. Not that projects need to be messy to be authentic, mind you, but there are some that are just so finished and professional looking that it gives us a bit of pause. [Sebastian]’s programmable precision resistor is a shining example of such a project

While [Sebastian] describes this as “a glorified decade resistance box,” and technically that’s exactly right — at its heart it’s just a bunch of precision resistors being switched into networks to achieve a specific overall resistance — there’s a lot more going on here than just that. The project write-up, which has been rolling out slowly over the last month or so, has a lot of detail on different topologies that could have been used — [Sebastian] settled on a switched series network that only requires six relays per decade while also minimizing the contribution of relay contact resistance to the network. Speaking of which, there’s a detailed discussion on that subject, plus temperature compensation, power ratings, and how the various decades are linked together.

For as much that’s interesting about what’s under the hood, we’d be remiss to not spend a little time praising the exterior of this instrument. [Sebastian] appears to have spared no expense to make this look like a commercial product, from the rack-mount enclosure to the HP-esque front panel. The UI is all discrete pushbuttons and knobs with a long string of 16-segment LEDs — no fancy touch-screens here. The panel layout isn’t overly busy, and looks like it would be easy to use with some practice. We’d love to hear how the front and rear panel overlays were designed, too; maybe in a future project update.

This honestly looks like an instrument that you’d pay a princely sum to Keithley or H-P to own, at least back in the late 1990s or so. Kudos to [Sebastian] for the attention to detail here.

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Litter Box Sensor Lets You Know Exactly What The Cat’s Been Up To

August 17, 2023 by 16 Comments

In our experience, there’s rarely any question when the cat uses the litter box. At all. In the entire house. For hours. And while it may be instantly obvious to the most casual observer that it’s time to clean the thing out, that doesn’t mean there’s no value in quantifying your feline friend’s noxious vapors. For science.

Now of course, [Owen Ashurst] could have opted for one of those fancy automated litter boxes, the kind that detects when a cat has made a deposit and uses various methods to sweep it away and prepare the box for the next use, with varying degrees of success. These machines seem like great ideas, and generally work pretty well out of the box, but — well, let’s just say that a value-engineered system can only last so long under extreme conditions. So a plain old-fashioned litterbox suffices for [Owen], except with a few special modifications. A NodeMCU lives inside the modesty cover of the box, along with a PIR sensor to detect the cat’s presence, as well as an MQ135 air quality sensor to monitor for gasses. It seems an appropriate choice, since the sensor responds to ammonia and sulfides — both likely to be present after a deposit. Continue reading “Litter Box Sensor Lets You Know Exactly What The Cat’s Been Up To” →

2023 Cyberdeck Contest: Cyberdeck Red Is Ready For Action

August 17, 2023 by 8 Comments

What exactly constitutes a cyberdeck is up for debate, but for us, one thing is clear: A cyberdeck needs to look like it’s ready to go to battle. When the machines finally rise up and try to wipe us all out, someone toting around a machine like Cyberdeck Red is probably going to be a sight for sore eyes; clearly, such a person would be equipped to help us fight back the robotic scourge.

If this cyberdeck looks familiar, it’s for a good reason — it’s [Gabriel]’s second stab at this build. We thought the original was pretty keen, enough so that it won second prize in the 2022 contest. But like many cyberdeck builders, good enough isn’t good enough, and so rather than rest on his laurels, he set about improving a few things. The most visible of the changes are the spiffy new case, which is far less utilitarian than version one, and the new custom-made split keyboard. Things are a little different under the hood too; gone is the Raspberry Pi 4, which was replaced by Latte Panda 3 Delta running Windows. And like the original, version two is absolutely stuffed with sensors and diagnostic gear — a Hack RF SDR for radio work, plus an Analog Discovery 2 which provides everything from an oscilloscope and signal generator to a spectrum analyzer and an impedance tester.

But possibly the most useful feature of Cyberdeck Red is the onboard HDMI projector. The palm-sized, short-throw projector would be perfect for an impromptu combat briefing in an improvised command post, or just watching Netflix. If the machines will allow it, of course.

The 2023 Cyberdeck Contest wraps up August 15, so it looks like [Gabriel] just squeaked this one in on time. We wish him and all the other entrants the best of luck!

The Dipole Antenna Isn’t As Simple As It Appears

August 16, 2023 by 47 Comments

Dipole antennas are easy, right? Just follow the formula, cut two pieces of wire, attach your feedline, and you’re on the air.  But then again, maybe not. You’re always advised to cut the legs a little long so you can trim to the right length, but why? Shouldn’t the math just be right? And what difference does wire choice make on the antenna’s characteristics? The simple dipole isn’t really that simple at all.

If you’ve got antenna questions, check out [FesZ]’s new video on resonant dipoles, which is a deep dive into some of the mysteries of the humble dipole. In true [FesZ] fashion, he starts with simulations of various dipole configurations ranging from the ideal case — a lossless conductor in free space with as close to zero diameter conductors as the MMANA antenna simulator can support — and gradually build up to more practical designs. Continue reading “The Dipole Antenna Isn’t As Simple As It Appears” →

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Hackaday Links: August 13, 2023

August 13, 2023 by 14 Comments

Remember that time when the entire physics community dropped what it was doing to replicate the extraordinary claim that a room-temperature semiconductor had been discovered? We sure do, and if it seems like it was just yesterday, it’s probably because it pretty much was. The news of LK-99, a copper-modified lead apatite compound, hit at the end of July; now, barely three weeks later, comes news that not only is LK-99 not a superconductor, but that its resistivity at room temperature is about a billion times higher than copper. For anyone who rode the “cold fusion” hype train back in the late 1980s, LK-99 had a bit of code smell on it from the start. We figured we’d sit back and let science do what science does, and sure enough, the extraordinary claim seems not to be able to muster the kind of extraordinary evidence it needs to support it — with the significant caveat that a lot of the debunking papers –and indeed the original paper on LK-99 — seem still to be just preprints, and have not been peer-reviewed yet.

So what does all this mean? Sadly, probably not much. Despite the overwrought popular media coverage, a true room-temperature and pressure superconductor was probably not going to save the world, at least not right away. The indispensable Asianometry channel on YouTube did a great video on this. As always, his focus is on the semiconductor industry, so his analysis has to be viewed through that lens. He argues that room-temperature superconductors wouldn’t make much difference in semiconductors because the place where they’d most likely be employed, the interconnects on chips, will still have inductance and capacitance even if their resistance is zero. That doesn’t mean room-temperature superconductors wouldn’t be a great thing to have, of course; seems like they’d be revolutionary for power transmission if nothing else. But not so much for semiconductors, and certainly not today.

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Stuffing A 32-Pin Chip Into A 28-Pin Socket

August 13, 2023 by 29 Comments

What’s the difference between a 64k ROM in a 28-pin DIP and a 128k ROM in a 32-pin DIP? Aside from the obvious answers of “64k” and “four pins,” it turns out that these two chips have a lot in common, enough so that it only takes a little bodging to make them interchangeable — more or less.

For a variety of reasons revealed in the video below, [Anders Nielsen] use the SST39SF010, a Flash ROM in a 32-pin DIP, in place of the old standby W27C512, an EEPROM in a 28-pin DIP. To deal with those pesky extra pins on the Flash ROM, [Anders] dug into the data sheets and found that thanks to JEDEC standards, almost everything about the pinouts of the two chips is identical. The only real difference is the location of Vcc, plus the presence of a 16th address bus line on the more capacious Flash ROM.

Willing to sacrifice the upper half of the Flash chip’s capacity, [Anders] set about bodging the 32-pin chip to work in a 28-pin socket. The mods include a jumper from pin 32 to pin 30 on the Flash chip, which puts Vcc in the right place, and adding a couple of pull-up resistors for write-enable and A16. Easy enough changes, but unfortunately, [Anders] chose a Flash ROM with heavily oxidized pins, leading to some cold solder joints and intermittent problems while testing. There’s also the fact that not all boards have room for overhanging pins, a problem solved by adding a socket to create a little vertical clearance.

We found this to be a neat little hack, one that should make it a bit easier to use the wrong chip for the job. If you want to see where [Anders] is using these chips, check out his 6502 in an Arduino footprint or the bring-up of an old XT motherboard.

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