Who doesn’t like to look up at the night sky? But if you are into radio, there’s a whole different way to look using radio telescopes. [John Makous] spoke at the GNU Radio Conference about how he’s worked to make a radio telescope that is practical for even younger students to build and operate.
The only real high tech part of this build is the low noise amplifier (LNA) and the project is in reach of a typical teacher who might not be an expert on electronics. It uses things like paint thinner cans and lumber. [John] also built some blocks in GNU Radio that made it easy for other teachers to process the data from a telescope. As he put it, “This is the kind of nerdy stuff I like to do.” We can relate.
The telescope is made to pick up the 21 cm band to detect neutral hydrogen from the Milky Way. It can map the hydrogen in the galaxy and also measure the rotational speed of the galaxy using Doppler shift. Not bad for an upcycled paint thinner can. These are cheap enough, you can even build a fleet of them.
This would be a great project for anyone interested in radio telescopes or space. However, it is particularly set up for classroom use. Students can flex their skills in math, engineering, programming, and — of course — astronomy and physics.
We’ve seen old satellite LNAs repurposed to radio telescopes. If you think you don’t have room for a radio telescope, think again.
Modern smartphones are highly integrated devices, bringing immense computing power into the palm of one’s hand. This portable computing power and connectivity has both changed society in innumerable ways, and also tends to lead to said powerful computers ending up dropped on the ground or into toilets. Repairs are often limited to screen replacement or exchanging broken modules, but it’s possible to go much further.
The phone is an iPhone 7, which a service center reported had issues with the CPU, and the only fix was a full mainboard replacement. [The Kardi Lab] weren’t fussed, however, and got to work. The mainboard is installed in a CNC fixture, and the A10 CPU is delicately milled away, layer by layer. A scalpel and hot air gun are then used for some further cleanup of the solder pads. Some conductivity testing to various pads is then carried out, for reasons that aren’t entirely clear.
At this point, a spare A10 CPU is sourced, and a stencil is used to apply solder paste or balls – it is not immediately obvious which. The new chip is then reflowed on to the mainboard, and the phone reassembled. The device is then powered on and shown to be functional.
It’s an impressive repair, and shows that modern electronics isn’t so impossible to fix – as long as you have the right tools to hand. The smart thing is, by using the CNC machine with a pre-baked program, it greatly reduces the labor required in the removal stage, making the repair much more cost-effective. The team are particularly helpful, linking to the tools used to pull off the repair in the video description. We’ve seen similar hacks, too – such as upgrading an iPhone’s memory. Video after the break.
[Thanks to Nikolai for the tip!]
Knobs! Shiny candy-colored knobs! The last stand of skeuomorphism is smart light switches! Everyone loves knobs, but when you’re dealing with vintage equipment with a missing knob, the odds of replacing it are slim to none. That’s what happened to [Wesley Treat] when he picked up a vintage Philco tube tester. The tester looked great, but a single knob for a rotary switch was missing. What to do? Clone some knobs! You only need some resin and a little bit of silicone.
The process of copying little bits of plastic or bakelite is fairly standard and well-tread territory. Go to Michaels or Hobby Lobby, grab some silicone and resin, make a box, put your parts down, cover them in silicone, remove the parts, then put resin in. For simple parts, and parts with flat bottoms like knobs, this works great. However, there’s something weird about the knob on this old Philco tube tester. Firstly, it doesn’t fit a standard 1/4″ shaft — it’s a bit bigger. There’s also no set screw. Instead, this knob has a stamped spring aligning it with the flat part of the D-shaft in this rotary switch. This means a copy of this knob wouldn’t be useful to anyone else, and that no other knob would work with this tube tester.
However, a bit of clever engineering would make a copy of this knob fit the existing switch. Once the resin was cured, [Wesley] drilled out the hole, then sanded a dowel down to fit into the flat of the D-shaft. It took a little kergiggering, but the knob eventually fit onto one of the rotary switches. Not bad for a few bucks in silicone and resin.
You can check out the entire build process below.
Despite a lot of advances in battery technology, lead acid batteries are still used in many applications due to cost and their ability to provide a lot of surge current. But they don’t last forever. However, [AvE] shows that in some cases a failed battery can be restored with — of all things — epsom salts. If it makes you feel funny to use the stuff grandpa soaks in when he has a backache, you can call it magnesium sulfate.
You can find a complete explanation in the video below (which includes [AvE’s] very colorful language), but fundamentally, the magnesium sulfate dissolves lead sulfate build-up on the battery plates. The fix is usually temporary because this build-up occurs with other failure mechanisms like plate material shedding and collecting at the bottom of the battery. Obviously, epsom salt can’t repair damaged plates or do any other magic cure.
We really enjoyed that [AvE] tore open a battery to show the plates and what was really happening inside. He also explains why the epsom salt might help.
We were surprised that he poured the salt directly into the battery. We were always taught to heat up some distilled water and saturate it with the epsom salt. Then you’d filter out any solid left and pour the water/salt mixture in until it couldn’t take any more.
Not only does this not always work, but it also doesn’t work instantly. We’ve heard of batteries treated with epsom salt or caustic soda reviving after several weeks. However, even if you don’t want to restore a battery with salt, there’s plenty of interesting battery facts and lore in the video that you’ll find interesting.
Everyone loves to point out how just about any project could have used a 555. That chip can charge your battery after you repair it. This isn’t the first time we’ve contemplated salting a battery, by the way. On the other hand, you can make a peculiar battery out of molten salt.
The lathe is a simple enough tool to understand, but requires much practice to truly master. During the turning process, it’s often necessary to inspect the workpiece. This generally necessitates stopping the lathe, waiting for everything to spin down, and then starting again. This can be a major time sink when added up across the full scope of a project. However, the magic of strobes can help.
The basics of [Darcy]’s project will be familiar to any hacker who has worked with rotating machinery before. The rotational speed of the lathe is measured, in this case using a reed switch and a magnet. This signal is fed to a microcontroller, which controls the strobing of an LED lamp. By synchronizing the flashes to the speed of the lathe, it’s possible to view the workpiece as if it were standing still. By adjusting the offset of the flashes to the position of the lathe, it’s also possible to rotate this view to see the entire workpiece – all while the lathe remains spinning.
Further photos and videos are available in the Reddit thread. [Darcy] reports that despite his best efforts, he couldn’t quite find a business case for producing the hardware commercially, but the idea was too useful to leave languishing in a notebook. We’d love to hear your ideas on how this could improve turning projects, so be sure to let us know in the comments. If you’re just getting started with turning, it might be worth cutting a test bar to make sure your rig is up to snuff.
The month or so after the holidays have always been a great time to pick up some interesting gadgets on steep clearance, but with decorations and lights becoming increasingly complex over the last few years, the “Christmas Clearance” rack is an absolute must see for enterprising hackers. You might just luck out like [ModernHam] and find a couple packs of these dirt cheap wireless light controllers, which can fairly easily be hacked into the start of a home automation system with little more than the Raspberry Pi and a short length of wire.
In the video after the break, [ModernHam] walks the viewer through the start to finish process of commanding these cheap remote plugs. Starting with finding which frequencies the remotes use thanks to the FCC database and ending with using cron to schedule the transmission of control signals from the Pi, his video really is a wealth of information. Even if you don’t have this particular model of remote plug, or don’t necessarily want to setup a home automation system, there’s probably some element of this video that you could still adapt to your own projects.
The first step of the process is figuring out how the remote is communicating to the plugs. [ModernHam] noticed there was no frequency listed on the devices, but using their FCC IDs he was able to find the relevant information. In the United States, devices like these must have their FCC IDs visible (though they could be behind a battery door) by law, so the searchable database is an invaluable tool to do some basic reconnaissance on a poorly documented gadget.
An RTL-SDR receiver is then used to fine tune the information gleaned from the FCC filing. [ModernHam] found that the signals for all four of the remote plugs were being broadcast on the same frequency, which makes controlling them all the easier. Using the
rtl-sdr command, he was able to capture the various signals from the transmitter and save them to separate files. Then it’s just a matter of replaying the appropriate file to get the plugs to do your bidding.
Of course, the RTL-SDR can’t transmit so you’ll have to leave your dongle behind for this last step. Luckily all you need to transmit is the rpitx package created by [F5OEO], along with a supported Raspberry Pi and a small length of wire attached to the appropriate GPIO pin. This package contains the tool
sendiq which can be used to replay the raw captures made in the previous step. With some scripting, it’s fairly straightforward to automate these transmissions to control the remote plugs however you wish from the Pi.
The RTL-SDR Blog put together their own guide for “brute forcing” simple remote control devices like this as well, and we’ve even seen similar techniques used against automotive key fobs in the past. Amazing what a piece of wire and some clever code can pull off.
Fans of 80s-era computer printing technology are few and far between, but Apple’s ImageWriter II was a beast of a printer. This tractor feed dot-matrix printer is nigh-indestructible. The print quality was actually pretty great. It was loud as hell, which is a mark of quality electromechanical components. It could do color, and color dot-matrix art on tractor feed paper is the aesthetic we need. If you’re not convinced yet, you can also take off the perforations from tractor feed paper and make a cool little paper snake.
[Dandu] isn’t one to let things like serial printers and obsolete color dot matrix ribbons get in his way of creating ImageWriter art. A while ago, he printed off some incredible art using some obsolete equipment, and the results are better than what you would expect.
The process for creating full-color art on a dot-matrix printer was to plug the ImageWriter into an old Mac (an LC III in this case, with 12 MB of RAM). Photoshop (version 3.0!) was used to open a JPEG, and MacPallete II used to send the data to the printer. This isn’t a process that prints all the colors all at once; first the yellow is printed, and the tractor feed paper is brought back to the beginning. Then the magenta is printed, then the cyan, then the black. The single page of art took 20 minutes to print, and you can see a sped-up version of this process below.
Yes, the ImageWriter II can print in full color, but who cares about this now? A few people apparently — a company is now remanufacturing ImageWriter II color ribbons — opening the door to retro art for all. Yes, that ImageWriter in your basement still works, so let’s see what you can do with it.
In 1991, Apple released the Quadra line of computers, named after their utilization of the new Motorola 68040 CPU. The Quadra line initially consisted of two models, the Quadra 700 and the Quadra 900. These two models, and the Quadra 950, released as a slight upgrade to the 900, were the peak of performance. You could conceivably load these machines up with 256 Megabytes of RAM, in an era where hard drives hovered around 80 Megabytes. This much RAM would cost as much as a house. These were powerhouses, the first ProTools workstations, and they ran Jurassic Park. If you wanted peak performance in the early 90s, you got a Quadra.
The Quadra 900 and 950 were tower computers, and there were options for floppy, Zip drives, Bernoulli drives, and a CD-ROM drive. They were introduced a little before the ‘multimedia’ hubub, and right now, the plastic bezel for the CD-ROM option is an absurdly expensive piece of plastic. People have paid $150 for an original CD-ROM bezel. Seems like the perfect application of 3D printing, doesn’t it? That’s exactly what [360alaska] over on the 68k Macintosh Liberation Army forms did. The unobtanium bezel can now be sent off to Shapeways.
This project is a continuation of a thread where various forum members shared their .STLs for random bits of Apple plastic, ranging from rubber feet for PowerBooks to the clip-on ‘programmer’s switch’ for the Macintosh SE. The crowning achievement of this community endeavour is the Quadra 950 CD-ROM bezel. There are a few varieties, ranging from one that fits a standard 5 1/4″ drive, to a nearly exact replica of the official Apple offering for their official drive. All the files are there for the downloadin’.
Printing these bezels will be a bit of a challenge for a filament-based printer, but resin printers are getting cheap and Shapeways is always there for you. Painting to match the brominated patina of old plastic is also a challenge, but the forum members have had some success with off-the-shelf spray paints.
If you have experienced software defined radio (SDR) using the ubiquitous RTL SDR dongles, you are missing out on half of it. While those SDRs are inexpensive, they only receive. The next step is to transmit. [Corrosive] shows how he uses DATV Express along with a Lime SDR or a Pluto (the evaluation device from Analog Devices) to transmit video. He shows how to set it all up in the context of ham radio. An earlier video shows how to receive the signal using an SDR and some Windows software. The receiver will work with an RTL SDR or a HackRF board, too. You can see both videos, below.
The DATV Express software has plenty of options and since SDR if frequency agile, you ought to be able to use this on any frequency (within the SDR range) that you are allowed to use. At the end, he mentions that to really put these on the air you will want a filter and amplifier since the output is a bit raw and low powered.
If you are old enough to remember when a TV transmitter was a big box full of circuitry, seeing video pour out of a little circuit board is pretty amazing. What’s more, is that on transmit and receive you can do an impressive amount of processing in software that would have been very advanced using traditional hardware.
Oddly enough, the RTL SDR was originally made to receive TV anyway. You can actually do the transmit with nothing but a Raspberry Pi, and [Corrosive] mentioned he’ll do a video about that soon.
Posted in amateur radio, atv, DATV Express, DVB-S, DVBS, ham radio, Lime SDR, pluto sdr, radio hacks, SDRAngel, tv, video hacks
There’s a lot of debate over which of several contenders was the first modern computer. One of those first operating computers was the University of Cambridge’s EDSAC — the brainchild of Dr. Maurice Wilkes. The EDSAC scored a lot of firsts and used a serial data path along with mercury delay line memories. Over on Hackaday.io, [David Boucher] wanted to simulate the EDSAC in a much smaller form factor than the original room full of racks.
As you can see in the video below, he succeeded in that task, using a Teensy and a small LCD display. We’re reminded EDSAC was among the first machines so some of the terms we would employ were not in use yet. An order is an instruction, for example. Initial orders are akin to a bootloader.
You think of computer sounds as a modern thing, but the EDSAC had a speaker connected to the sign bit of the accumulator and operators could hear programs in operation. With time, they could recognize certain things about a program’s execution based upon the sound.
You can see some vintage 1949 programs running deliberately slowed down because the new hardware can run much faster than the original. We are guessing there’s no mercury in the replica, neither did he original machine have a 3D printed case.
If you want to know more about EDSAC, there is a wealth of information out there and we’ve covered it before. If you don’t want to build, you can run EDSAC in your browser.