China Plans Its Own Megaconstellation To Challenge Starlink

June 22, 2023 by Lewin Day 39 Comments

Satellite internet used to be a woeful thing. Early networks relied on satellites in geostationary orbits, with high latency and minimal bandwidth keeping user demand low. That was until Starlink came along, and provided high-speed, low-latency internet access using a fleet of thousands of satellites in Low Earth orbit.

Starlink has already ruffled feathers due to concerns around light pollution and space junk in particular. Now, it appears that China may be readying its own competing constellation to avoid being crowded out of low orbits by the increasingly-popular service.

Continue reading “China Plans Its Own Megaconstellation To Challenge Starlink” →

The Many Robots That Ventured Into The Chernobyl NPP #4 Reactor

June 22, 2023 by Maya Posch 14 Comments

Before the Chernobyl Nuclear Power Plant (ChNPP, spelled ‘Chornobyl’ in Ukrainian) disaster in 1986, there had been little need for radiation-resistant robots to venture into high-risk zones.

Yet in the aftermath of the massive steam explosion at the #4 reactor that ripped the building apart — and spread radioactive material across the USSR and Europe — such robots were badly needed to explore and provide clean-up services. The robots which were developed and deployed in a rush are the subject of a recent video by [The Chornobyl Family].

While some robots were more successful than others, with the MF-2 remote mine handling robot suffering electronic breakdowns, gradually the robots became more refined. As over the years the tasks shifted from disaster management to clean-up and management of the now entombed #4 reactor, so too did the robots. TR-4 and TR-5 were two of the later robots that were developed to take samples of material within the stricken reactor, with many more generations to follow.

The video also reveals the fate of many of these robots. Some are buried in a radioactive disposal site, others are found on the Pripyat terrain, whether set up as a tourist piece, or buried in shrubbery. What’s beyond doubt is that it are these robots that provided invaluable help and saved countless lives, thanks to the engineers behind them.

Continue reading “The Many Robots That Ventured Into The Chernobyl NPP #4 Reactor” →

Inside Digital Calipers

June 22, 2023 by Al Williams 51 Comments

If you do any kind of machining, 3D printing, or PCB layout, you probably have at least considered buying a pair of calipers. Old-fashioned ones had a dial and were mechanical devices, but lately, digital ones have become quite affordable. We keep meaning to tear a set of ours apart to see what’s inside, but thanks to [learnelectronics], we don’t have to — the video below provides a fascinating look at what’s inside a cheap pair of Harbor Freight calipers.

Honestly, it doesn’t seem like it would be that hard to figure out how far down a bar you are. The trick is the caliper has to be super accurate. Oddly enough, the cheap calipers examined use capacitors as a sensing element.

There is a long flexible PCB stuck to the sliding part with conductive pads. The display unit is also a printed circuit and manages the battery, the display, and the other half of the capacitive sensor. If you want a more detailed explanation of how the sensor actually works, check out capsense.com. If you note, the pattern on the sliding part has traces that look like a square wave, and half have a different phase than the other half. These are the sine plates and the cosine plates. A 100 kHz signal flows through the capacitor, and it is possible to read the direction of travel and the amount of travel easily.

The calipers are very accurate, but it’s possible to improve them. A more practical project is to make them communicate with the outside world.

Continue reading “Inside Digital Calipers” →