It is a well-known reality of rescuing certain older electronic devices that, at some point, you’re likely going to have to replace a busted capacitor. This is the stage [Kevin] is at in the 3rd installment in his saga of reviving a 50-year-old Military Tektronix oscilloscope.
[Kevin] recently discovered a failed capacitor in the power supply for this vintage analog scope. Having identified and removed the culprit, it was time to find a way to replace the faulty component with a modern equivalent. The original capacitor is out of fashion to the degree that a perfect replacement would be impractical and likely not desirable. This job would call for a bit of adaptation.
Predicting the future is a dangerous occupation. Few people can claim as much success as Arthur C. Clarke, the famous science and science fiction author. Thanks to the BBC and the Australian Broadcasting Company, we can see what Sir Arthur thought about the future in 1964 and then ten years later in 1974.
Perhaps his best-known prediction was that of communication satellites, but he called quite a few other things, too. Like all prognosticators, he didn’t bat a thousand, and he missed a wrinkle or two, but overall, he has a very impressive track record.
If you’re a mechanical engineering wonk, you might appreciate this latest video from [Henry Segerman] wherein he demonstrates his various expanding racks.
[Henry] explains how the basic “double-rack” unit can be combined to make more complex structures. These structures are similar in spirit to the Hoberman sphere, which is a compact structure that can be expanded to fill a large space.
For a world covered in oceans, getting a drink of water on Planet Earth can be surprisingly tricky. Fresh water is hard to come by even on our water world, so much so that most sources are better measured in parts per million than percentages; add together every freshwater lake, river, and stream in the world, and you’d be looking at a mere 0.0066% of all the water on Earth.
Of course, what that really says is that our endowment of saltwater is truly staggering. We have over 1.3 billion cubic kilometers of the stuff, most of it easily accessible to the billion or so people who live within 10 kilometers of a coastline. Untreated, though, saltwater isn’t of much direct use to humans, since we, our domestic animals, and pretty much all our crops thirst only for water a hundred times less saline than seawater.
While nature solved the problem of desalination a long time ago, the natural water cycle turns seawater into freshwater at too slow a pace or in the wrong locations for our needs. While there are simple methods for getting the salt out of seawater, such as distillation, processing seawater on a scale that can provide even a medium-sized city with a steady source of potable water is definitely a job for Big Chemistry.
It’s never a bad time to look at a clock, and one could certainly do worse than this delightful Paper Sunshine Clock by [anneosaur]. The sun-ray display is an interesting take on the analog clock, and its method of operation is not one we see every day, either.
Reading the clock is straightforward: there are twelve rays divided into two segments. Once you figure out that this artful object is a clock, it’s easy enough to guess that the rays give the hours, and half-rays are half-hours. In the photo above, it’s sometime between nine o’clock and nine thirty. Our Swiss readers might not be terribly impressed, but a “fuzzy” clock like this is quite good enough much of the time for many people.
Even the flex PCB holding the resistors looks like a work of art.
The title gives away its method of operation: it’s thermochromic paint! The paint is printed onto a piece of Japanese awagami paper, which is pressed against a flexible PCB holding an array of resistors. Large copper pads act as heat spreaders for the resistors. For timekeeping and control, an Atmega328PB is paired with a DS3231MZ RTC, with a coin cell for backup power when the unit is unplugged. (When plugged in, the unit uses USB-C, as all things should.) That’s probably overkill for a +/-30 minute display, but we’re not complaining.
The Atmega328PB does not have quite enough outputs to drive all those resistors, so a multiplexing circuit is used to let the 10 available GIPO control current to 24 rays. Everything is fused for safety, and [anneosaur] even includes a temperature sensor on the control board. The resistors are driven by a temperature-compensated PWM signal to keep them from overheating or warming up too slowly, regardless of room temperature. The attention to detail here is as impressive as the aesthetics.
[annenosaur] has even thought of those poor people for whom such a fuzzy clock would never do (be they Swiss or otherwise) — the Paper Sunshine Clock has a lovely “sparkle mode” that turns the rays on and off at random, turning the clock into an art piece. A demo video of that is below. If you find this clock to be a ray of sunshine, everything you need to reproduce it is on GitHub under an MIT or CC4.0 license.
Special thanks to [anneosaur] for submitting the hack. If you’ve seen (or made) a neat clock, let us know! You won’t catch us at a bad time; it’s always clock time at Hackaday.
[Doug Brown] had a problem. He uses a dummy HDMI plug to fool a computer into thinking it has a monitor for when you want to run the computer headless. The dummy plug is a cheap device that fools the computer into thinking it has a monitor and, as such, has to send the Extended Display ID (EDID) to the computer. However, that means the plug pretends to be some kind of monitor. But what if you want it to pretend to be a different monitor?
The EDID is sent via I2C and, as you might expect, you can use the bus to reprogram the EEPROM on the dummy plug. [Doug] points out that you can easily get into trouble if you do this with, for example, a real monitor or if you pick the wrong I2C bus. So be careful.
As useful as corrugated cardboard is, we generally don’t consider it to be a very sturdy material. The moment it’s exposed to moisture, it begins to fall apart, and it’s easily damaged even when kept dry. That said, there are ways to make corrugated cardboard a lot more durable, as demonstrated by the [NightHawkInLight]. Gluing multiple panels together so that the corrugation alternates by 90 degrees every other panel makes them more sturdy, with wheat paste (1:5 mixture of flour and water) recommended as adhesive.
Other tricks are folding over edges help to protect against damage, and integrating wood supports. Normal woodworking tools like saws can cut these glued-together panels. Adding the wheat paste to external surfaces can also protect against damage. By applying kindergarten papier-mâché skills, a custom outside layer can be made that can be sanded and painted for making furniture, etc.
