A Lightweight Two Metre Carbon Fibre Yagi Antenna

February 13, 2017 by Jenny List 27 Comments

If you’ve ever cast your eye towards the rooftops, you’ll be familiar with the Yagi antenna. A dipole radiator with a reflector and a series of passive director elements in front of it, you’ll find them in all fields of radio including in a lot of cases the TV antenna on your rooftop.

In the world of amateur radio they are used extensively, both in fixed and portable situations. One of their most portable uses comes from the amateur satellite community, who at the most basic level use handheld Yagi antennas to manually track passing satellites. As you can imagine, holding up an antenna for the pass of a satellite can be a test for your muscles, so a lot of effort has gone into making Yagis for this application that are as lightweight as possible.

[Tysonpower] has a contribution to the world of lightweight Yagis, he’s taken a conventional design with a PVC boom and updated it with a stronger and lighter boom made from carbon fibre composite pipe. The elements are copper-coated steel welding rods, some inexpensive aluminium clamps came from AliExpress, and all is held together by some 3D-printed parts. As a result the whole unit comes in at a claimed bargain price of under 20 Euros.

This antenna is for the 2 M (144 MHz) amateur band, but since it’s based on the [WB0CMT] “7 dB for 7 bucks” (PDF) design it should be easily modified for other frequencies. The 3D printed parts can be found on Thingiverse, and he’s also posted a couple of videos in German. We’ve posted the one showing the build below the break, you can find the other showing the antenna being tested at the link above.

Continue reading “A Lightweight Two Metre Carbon Fibre Yagi Antenna” →

Vintage Laptop Keyboard Types Again Through USB

February 13, 2017 by Jenny List 24 Comments

Have you ever had a laptop you just wish you didn’t have to retire when its specification becomes to aged for your needs? Wouldn’t it be great if you could upgrade it and keep using the physical hardware!

[Alpinedelta] has a vintage Toshiba T1000 laptop, roughly a PC-XT clone from the late 1980s. Its 80C88 processor, CGA display, and 512k of memory make it a museum-piece, but he has plans to modernise it using a LattePanda Intel Atom based single board computer.

To make that happen, he has to ensure all the Toshiba’s peripherals will talk to a modern host. Unfortunately back in the 1980s many PC clones were clones in a rather loose sense, and especially so in the laptop arena. Thus there are no handy standard PC interfaces and since USB was several years away at the time, nothing the LattePanda can talk to directly. His solution for the keyboard is to wire its matrix directly to a Teensy microcontroller that then provides a USB interface, and he’s put up a useful step-by-step Instructables guide.

There is no standard for a laptop keyboard matrix, so the first and most tedious task is to unpick its layout.This he did by identifying each trace and assigning a different rainbow colour to it, before noting down which keys appeared on it and collating the results in a spreadsheet. The different colours of wire could then be assigned to the colours of a piece of rainbow ribbon cable, and wired in sequence to the Teensy’s I/O pins. There then follows a step in the software in which he assigns the pin mappings to the lines in his spreadsheet, then the sketch can be compiled and uploaded to the Teensy. Result: a vintage keyboard now talking USB.

Using a Teensy to present a USB keyboard to the world is a well-worn path, we’ve seen it with both newer keyboards and other relics like this one from a DEC VT100.

Thanks [Brent] for the tip.

How To Receive Pictures From Spaaace!

February 13, 2017 by Jenny List 24 Comments

The International Space Station, or ISS, has been in orbit in its various forms now for almost twenty years. During that time many of us will have stood outside on a clear night and seen it pass overhead, as the largest man-made object in space it is clearly visible without a telescope.

Most ISS-watchers will know that the station carries a number of amateur radio payloads. There are voice contacts when for example astronauts talk to schools, there are digital modes, and sometimes as is happening at the moment for passes within range of Moscow (on Feb. 14, 11:25-16:30 UTC) the station transmits slow scan television, or SSTV.

You might think that receiving SSTV would be hard work and require expensive equipment, but given the advent of ubiquitous mobile and tablet computing alongside dirt-cheap RTL-SDRs it is now surprisingly accessible. An Android phone can run the SDRTouch software defined radio app as well as the Robot36 SSTV decoder, and given a suitable antenna the pictures can be received and decoded relatively easily. The radio must receive 145.8MHz wideband FM and the decoder must be set to the ~~PD120~~ PD180 mode (Thanks [M5AKA] for the update), and here at least the apps are run on separate Android devices. It is possible to receive the signal using extremely basic antennas, but for best results something with a little gain should be used. The antenna of choice here is a handheld [HB9CV] 2-element beam.

A failed grab from a 2014 transmission, proving that Hackaday scribes don't always get perfect results. — A failed grab from a 2015 transmission, proving that Hackaday scribes don’t always get perfect results.

You can find when the station is due to pass over you from any of a number of ISS tracker sites, and you can keep up to date with ISS SSTV activity on the ARISS news page. Then all you have to do is stand out in the open with your receiver and computing devices running and ready, and point your antenna at the position of the station as it passes over. If you are lucky you’ll hear the tones of the SSTV transmission and a picture will be decoded, if not you may receive a garbled mess. Fortunately grabs of other people’s received pictures are posted online, so you can take a look at what you missed if you don’t quite succeed.

Even if you don’t live within range of a pass, it’s always worth seeing if a Web SDR somewhere is in range. For example this Russian one for the current transmissions.

In that you are using off-the-shelf hardware and software you might complain there is little in the way of an elite hack about pulling in a picture from the ISS. But wait a minute — you just received a picture from an orbiting space station. Do that in front of a kid, and see their interest in technology come alive!

Raspberry Pi Laptop Uses The Official Touchscreen

February 12, 2017 by Jenny List 20 Comments

We’ve seen a variety of home-made laptops using the Raspberry Pi and other single board computers over the years. Usually, they combine off-the-shelf USB keyboards and trackpads with HDMI monitor panels, and cases made from layered laser cut sheet, or 3D printed plastic.

[Surferboy]’s Raspberry Pi laptop is the latest effort to come before us, and its claim to fame is the use of the official Raspberry Pi 7″ touchscreen as a display. Full instructions and 3D printer files are available on Thingiverse so you can have a go at replicating it if a portable Pi is your thing.

He’s taken the bold step of not attempting to place all the Pi’s interfaces next to the outside of the case. Instead, he’s desoldered the Ethernet and USB ports. The USB connections were wired directly to the keyboard, display, and a couple of external ports on the right-hand side of his case. This leaves the finished laptop with no Ethernet. However, losing ethernet is a worthy tradeoff for the thinner package.

[Surferboy] also brought the GPIO header to a female socket on the rear of the unit. It’s unclear exactly what battery he uses except for a reference to the battery from his keyboard. Since a keyboard battery will be too small for Pi and display we are guessing a larger pack will be necessary.

Though the Ethernet port and battery issue would probably be a dealbreaker here this has the makings of a useful and compact laptop, it will be interesting to see if it is picked up and refined by the community.

Quite a few early Pi laptops used the Motorola Lapdock, a mobile-phone-into-netbook peripheral. Some others we’ve featured have been a bit chunky, but sometimes they can be objects of beauty.

Via Recantha.co.uk.

An Astronomical Observatory For Your Front Yard

February 11, 2017 by Jenny List 11 Comments

[Barry Armstead] is an astronomy enthusiast who built his own observatory in his front yard, in Canberra, Australia. It was a fine observatory as home-made observatories go, but he describes it as being small and cramped. His replacement was on an entirely different scale though, a building created by hand and which no doubt many readers would be pleased to own.

His design started with a cardboard model, and has a downstairs room upon which sits a rotatable dome with two sliding sections to form the observation window. The original observatory’s concrete pillar on which the telescope mount stood remained post-demolition, and a larger concrete pad was laid. There followed the assembly of a steel frame with a skeletal dome able to rotate on rollers, followed by cladding with steel sheet. The dome cladding was done in segments marked against the dome steelwork and cut to shape.

The final building has a fully finished interior downstairs, plus a rustic staircase to the upper deck. The concrete post has been extended, and now carry’s [Barry]’s telescope which he controls not with his eye clued to an eyepiece like the astronomers of old, but from a computer at the adjacent desk. The full construction details are on the observatory’s web site, though since it seems in danger of disappearing due to an expired hosting account we’ll also give you a Wayback Machine link direct to the relevant page. Meanwhile he offers a tour in a video we’ve placed below the break. Even a non-astronomer would find this an asset in their garden!

Continue reading “An Astronomical Observatory For Your Front Yard” →

Press Button, Receive Hackspace WiFi Code

February 10, 2017 by Jenny List 18 Comments

When you are running a hackspace, network security presents a particular problem. All your users will expect a wireless network, but given the people your space will attract, some of them are inevitably going to be curious enough to push at its edges. Simply plugging in a home WiFi router isn’t going to cut it.

At Santa Barbara Hackerspace they use Unifi access points on their wireless network, and their guest network has a system of single-use codes to grant a user 24-hour access. The system has the ability to print a full sheet of codes that can be cut individually, but it’s inconvenient and messy. So the enterprising hackspace members have used a Raspberry Pi and a receipt printer to deliver a single code on-demand at the press of a button.

The hardware is simple enough, just a pull-up and a button to a GPIO on the Pi. Meanwhile the software side of the equation has a component on both client and server. At the server end is a Python script that accesses the Unifi MongoDB database and extracts a single code, while at the client end is another Python script that reacts to a button press by calling the server script and printing the result. It’s a simple arrangement that was put together in an evening, but it’s an effective solution to their one-time WiFi access needs.

It’s a temptation as a hackspace to view all of your problems as solvable in one go with the One Piece Of Software To Rule Them All, and as a result some spaces spend a lot of time trying to hack another space’s effort to fit their needs or even to write their own. But in reality it is the small things like this one that make things work for members, and in a hackspace that’s important.

Does your space have any quick and simple projects that have automated a hackspace process? Let us know in the comments.

Thanks [Swiss] for the tip.

Iron Man, In IRON!

February 9, 2017 by Jenny List 28 Comments

Sometimes a project comes our way which has so much information contained in it as to be overwhelming, and on which it is difficult to know where to start. A good example is [Barry Armstead]’s Iron Man suit, to which we were introduced through a very long forum thread that spans several years.

Home-made armour is a staple of the cosplay world, with many astoundingly good creations being produced by fans. What makes [Barry]’s Iron Man suit stand out from the crowd is its construction; instead of fiberglass or vacuum-formed plastic he’s used real metal. (It’s steel. But steel contains iron, right? We’re calling poetic license.)

The best place to follow progress on the suit is probably [Barry]’s YouTube feed, in which he has so far racked up 44 build logs. We see joint articulation tests, early test walks, the iconic helmet taking shape, and the repulsor simulated with a nano sprayer. With so many videos to watch, you’ll be there quite a while. The one we’ll leave you with below the break is fairly straightforward, the first look at the entire exoskeleton in bare metal.

Continue reading “Iron Man, In IRON!” →