Everest isn't the most difficult mountain in the world to climb, but it is one of the most expensive. The individual cost of getting one's athletic ass to the top of the mountain range is between $40,000-$130,000. Most of this cheddar gets thrown at logistics. It takes a lot of money for a mountain outfitter to set up multiple camps at varying altitudes along the route to the top of the world. It takes considerably less money to hire the ludicrously underpaid Sherpa guides to set it all up and, if things go well, get their clients up the side of Everest and back down to base camp again in one piece. This in-depth video explains it all.
Australia's Paleotronic is celebrating Christmas with twelve posts celebrating the best seasonal computer ads of the years between 1980 and 1992; today is day 1: 1980, in all its Coleco gloriousness. (Thanks, Gnat!)
The Pocket High Voltage Generator that I made a few weeks ago proved to be a very handy tool. I have been testing Zener diodes very often since I use many Zeners in 12V to 91V range.
However I wanted to give it a bit more power so that I can test Nixie tubes clearly – the previous design can only give less than 0.5 mA through most Nixie tubes, some digits don’t lit up completely.
I made some upgrades to the components to give it a modest 2 – 5 mA (depending on the voltage) output. While still keeping the same form factor.
Certain hobbies come in clusters. It isn’t uncommon to see, for example, ham radio operators that are private pilots. Programmers who are musicians. Electronics people who build model trains. This last seems like a great fit since you can do lots of interesting things with simple electronics and small-scale trains. [Jimmy] at the aptly-named DIY and Digital Railroad channel has several videos on integrating railroad setups with Arduino. These range from building a DCC system for about $45 (see below) to a crossing signal.
There are actually quite a few basic Arduino videos on the channel, although most of them are aimed at beginners. However, the DCC — Digital Command and Control — might be new to you if you are a train neophyte. DCC is a standard defined by the National Model Railroad Association.
Model trains pick up electrical power from the rails. DCC allows digital messages to also ride the rail. The signal shifts from positive to negative to indicate marks and spaces. By diode switching the electrical signal, the train or other equipment can get a constant supply of current. However, equipment monitoring the line ahead of the diodes can read the data and interpret it as commands.
To accommodate old equipment, you can stretch the high or low values to make the average voltage either positive (forward) or negative (reverse). This can heat up DC motors, though, so it may shorten the life of the legacy equipment.
The build uses an available Arduino library, so if you want to get into the protocol you’ll have to work through that code. We had to wonder if there were other places where passing power and data on the same lines might be useful. There are other ways to do that, of course, but this would be a reasonable place to start if you needed that capability.
On the outside chance that we ever encounter a space probe from an alien civilization, the degree to which the world will change cannot be overestimated. Not only will it prove that we’re not alone, or more likely weren’t, depending on how long said probe has been traveling through space, but we’ll have a bonanza of super-cool new technology to analyze. Just think of the fancy alloys, the advanced biomimetic thingamajigs, the poly-godknowswhat composites. We’ll take a huge leap forward by mimicking the alien technology; the mind boggles.
Sadly, we won’t be returning the favor. If aliens ever snag one of our interstellar envoys, like one of the Voyager spacecraft, they’ll see that we sent them some really old school stuff. While one team of alien researchers will be puzzling over why we’d encode images on a phonograph record, another team will be tearing apart – an 8-track tape recorder?
Old School is Best School
Of course, there are plenty of reasons to send what would be counted as obsolete systems on Earth into space. Mitigating risk is a big part of the job of space exploration, and with the price for failure so high, only proven technologies are generally sent upstairs. That has been true for pretty much the entire history of space exploration and doubly so for manned missions; the Apollo Guidance Computers of the late 1960s were built around resistor-transistor logic (RTL) chips for this reason, even after transistor-transistor (TTL) logic chips had been available for most of the decade.
By the time the Voyager mission’s Grand Tour of the Solar System was being planned in the 1970s, NASA had a fair bit of experience building space probes. The Pioneer missions were the basis for much of what NASA learned, culminating with Pioneer 10 and Pioneer 11 probes being sent to explore beyond the asteroid belt for the first time. Those probes were extremely stripped down, at least as interplanetary spacecraft go, with no onboard data storage to speak of. Commands from the ground and data back down had to be sent in real time.
That would never cut it for Voyager, a much more extensive mission with a huge suite of scientific payloads, each of which generated far more data than could be instantaneously streamed. Voyager needed to save data and send it slowly back to earth. A NASA backgrounder on the Voyager missions shows that a data storage was specified that could buffer about 536 Mb, or the equivalent of 100 full-resolution photographs from the spacecraft’s camera.
The data tape recorder (DTR) system was subcontracted to Lockheed and manufactured by Odetics Corp. The specs show that the machine was a belt driven recorder that used a 1,076′ (328 m) long reel of 1/2″ (12.5 mm) wide magnetic tape which recorded data on eight separate tracks. The DTR could record at two different speeds – 115.2 kbps and 7.2 kbps. Playback topped out at a much slower 57.6 kbps, with 33.6, 21.6, and 7.2 kbps being options as well.
It appears that none of the non-flown DTRs exist in any museum collections anymore, and all we have is one picture of the mechanism. It’s clearly much more sophisticated than the standard 8-track cartridge transport for consumer use at the time.
This isn’t your grandfather’s 8-track. First, the tape does not appear to be in a continuous loop as it would in an 8-track cartridge. It appears to come off the lower reel and loop around several idlers and pinch rollers before passing through the read-write heads in the center of the unit. It then routes around several more idlers, two of which appear to be mounted on a rotating platform, before heading to the upper reel.
Built to Last
It’s hard to get an idea of the size of the DTR from this photograph, but another artifact exists that gives us some clues. The DTR was installed in a rack in the spacecraft that mounted inside one of the ten equipment bays located in a ring under the high-gain dish antenna. The Smithsonian has a DTR bay assembly in its collection, and lists the size as 24″ high x 19″ wide x 14″ deep (56 cm x 48 cm x 36 cm). Given the arrangement of the connectors on the backplane, the DTR is probably about 24″ tall and about 10″ wide.
Exactly what the composition of the magnetic tape was, and what secrets were used to prevent it from degrading in the harsh environment of space, are unclear. Odetics, the manufacturer, claimed that the tape would travel through the mechanism a distance of 2,700 mi (4,400 km) before discernible wear.
It seems to have worked. The DTRs in both spacecraft performed flawlessly from their launch in 1977 and through the entire Grand Tour mission, as well as the extended mission that set both vehicles on a course out of the solar system. In 2007, the DTR in Voyager 1 was shut down for good, not due to any issues with the unit, but because of the dwindling supply of power coming from the craft’s radioisotope thermal generators. As of this writing, the DTR in Voyager 2 is still working, but is likely to be shut down as the power wanes in that vehicle.
Soon we’ll lose contact with both of these platforms for good, and they’ll pass silently into the interstellar void. And if anyone does find them someday and learn how to power them back up, maybe those primitive tape recorders will spin back up one last time.
Maybe we did send our best stuff out there after all.
Want to explore the world of radar but feel daunted by the mysteries of radio frequency electronics? Be daunted no more and abstract the RF complexities away with this tutorial on software-defined radar.
Taking inspiration from our own [Gregory L. Charvat], whose many radar projects have graced our pages before, [Luigi Freitas]’ plunge into radar is spare on the budgetary side but rich in learning opportunities. The front end of the radar set is almost entirely contained in a LimeSDR Mini, a software-defined radio that can both transmit and receive. The only additional components are a pair of soup can antennas and a cheap LNA for the receive side. The rest of the system runs on GNU Radio Companion running on a Raspberry Pi; the whole thing is powered by a USB battery pack and lives in a plastic tote. [Luigi] has the radar set up for the 2.4-GHz ISM band, and the video below shows it being calibrated with vehicles passing by at known speeds.
True, the LimeSDR isn’t exactly cheap, but it does a lot for the price and lowers a major barrier to getting into the radar field. And [Luigi] did a great job of documenting his work and making his code available, which will help too.