DIY Loading Coil Shortens Antenna Lengths

November 20, 2023 by 24 Comments

A newly licensed amateur radio operator’s first foray into radios is likely to be a VHF or UHF radio with a manageable antenna designed for the high frequencies in these radio bands. But these radios aren’t meant for communicating more than a double-digit number of kilometers or miles. The radios meant for long-distance communication use antennas that are anything but manageable, as dipole antennas for the lowest commonly used frequencies can often be on the order of 50 meters in length. There are some tricks to getting antenna size down like folding the dipole in all manner of ways, but the real cheat code for reducing antenna size is to build a loading coil instead.

As [VA5MUD] demonstrates, a loading coil is simply an inductor that is placed somewhere along the length of the antenna which makes a shorter antenna behave as a longer antenna. In general, though, the inductor needs to be robust enough to handle the power outputs from the radio. There are plenty of commercial offerings but since an inductor is not much more than a coil of wire, it’s entirely within the realm of possibility to build them on your own. [VA5MUD]’s design uses a piece of PVC with some plastic spacers to wind some thick wire around, and then a customized end cap with screw terminals attached to affix the antenna and feedline to. Of course you’ll need to do a bit of math to figure out exactly how many turns of wire will be best for your specific situation, but beyond that it’s fairly straightforward.

It’s worth noting that the coil doesn’t have to be attached between the feedline and the antenna. It can be placed anywhere along the antenna, with the best performance typically being at the end of the antenna. Of course this is often impractical, so a center-loaded coil is generally used as a compromise. Coils like these are not too hard to wind by hand, but for smaller, lower-current projects it might be good to pick up a machine to help wind the coils instead.

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CinePi Project Promises Open Source Movie Making

November 20, 2023 by 19 Comments

Today, there’s open source options for pretty much anything mainstream, but that doesn’t mean there aren’t still some niches out there that could benefit from the libre treatment. The CinePi project is a perfect example — before today we didn’t even know that an open hardware and software cinema-quality camera was out there. But now that we do, we can’t wait to see what the community does with it.

Inside the 3D printed enclosure of the CinePi, there’s a Raspberry Pi 4 with HQ camera module, a four-inch touch screen, a Zero2Go power supply with four 18650 cells, and a Notcua fan to keep it all cool. The design intentionally favors modules that are easy to source from the usual online sources. You’ll need to be handy with a soldering iron to follow along with the beautifully photographed assembly guide, but there’s nothing that needs to be custom fabricated to complete the build.

The software was clearly developed with the user experience in mind, and in the video below, you can see how its touch interface makes it easy to change settings on the fly. While an amateur auteur might need to enlist the assistance of their geeky friend to build the CinePi, it doesn’t look like they’ll need them around to help operate it.

Of course, the big question with a project like this: what does the video actually look like? Well the technical answer is that, in terms of raw performance, the CinePi is able to capture 3840 x 2160 CinemaDNG video to an external device such as a NVME SSD or a CFExpress Card at 25 frames per second. But what that actually looks like is going to depend on what kind of post-processing you do to it. For the more practical answer, check out the short film TIMEKEEPER which was shot partially on a CinePi.

If this all looks a bit high-tech for your liking, don’t worry. You could always 3D print yourself a 35 mm movie camera instead.

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A Camera That Signs Off Your Pictures

November 20, 2023 by 38 Comments

We’ll admit we’ve kicked around the idea of a camera that digitally signs a picture so you could prove it hasn’t been altered and things like the time and place the photo was taken for years. Apparently, products are starting to hit the market, and Spectrum reports on a Leica that, though it will set you back nearly $10,000, can produce pictures with cryptographic signatures.

This isn’t something Leica made up. In 2019, a consortium known as the Content Authenticity Initiative set out to establish a standard for this sort of thing. The founders are no surprise: The New York Times, Adobe, and Twitter. There are 200 companies involved now, although Twitter — now X — has left.

The problem, the post notes, is that software support is limited. There are only a few programs that recognize and process digital signatures. That’ll change, of course, and — we imagine — if you needed to prove the provenance of a photo in court, you’d just buy the right software you needed.

We haven’t dug into the technology, but presumably keeping the private key secure will be very important. The consortium is clear that the technology is not about managing rights, and it is possible to label a picture anonymously. The signature can identify if an image was taken with a camera or generated by AI and details about how it was taken. It also can detect any attempt to tamper with the image. Compliant programs can make modifications, but they will be traceable through the cryptographic record.

Will it work? Probably. Can it be broken? We don’t know, but we wouldn’t bet that it couldn’t without a lot more reading. PDF signatures can be hacked. Our experience is that not much is truly unhackable.

Revive A Sony Vaio P-Series With KiCad’s Background Bitmaps

November 20, 2023 by 31 Comments

You might remember that KiCad 7 came out this February, with a multitude of wonderful features. One of them was particularly exciting to see, and the KiCad newsletter even had an animated GIF to properly demo it – a feature called “Background Bitmaps”, which is the ability to add existing board images into your board editor, both front and back, and switch between them as you design the board. With it, you can draw traces, recreate the outline and place connectors over these images, giving you a way to quickly to reproduce everything on an existing PCB! I’ve seen some friends of mine use this feature, and recently, I’ve had a project come up that’s a perfect excuse for me to try it.

By [Yoggy], CC-BY-2.0
Back in 2020, I managed to get a Sony Vaio P from a flea market, for about 20€. It’s a beloved tiny laptop from 2009, now a collectors item, and we’ve covered a few hacks with it! The price was this wonderful only because it was not fit for regular flea market customers – it was in bad condition, with the original DC jack lost and replaced by some Molex-like power connector, no hard drive, and no battery in sight.

In short, something worth selling to a known tinkerer like me, but not particularly interesting otherwise. Nevertheless, about half a year later, when I fed it the desired 10.5 V from a lab PSU and gave the power button a few chances, it eventually booted up and shown me the BIOS menu on the screen! I’ve disassembled and reassembled it a few times, replaced the DC jack with an original one from a different Vaio ultrabook I happened to have parts from, and decided to try to bring it back to original condition.

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CNC Plus Microscope Plus Game Controller Equals Awesome

November 20, 2023 by 4 Comments

What do you get if you strap a microscope onto a CNC and throw in a gaming controller? The answer, according to Reddit user [AskewedBox] is something kind of awesome: you get a microscope that can be controlled with the game controller for easier tracking of tiny creepy-crawlies.

[ASkewedBox] set up this interesting combination of devices, attaching their Adonostar AD246S microscope to the stage of a no-brand 1610 CNC bought off Amazon, then connected the CNC to a computer running Universal G-Code Sender. This great open source program takes the input from an Xbox game controller and uses it to jog the CNC.

With a bit of tweaking, the game controller can now move the microscope, so it can be used to track microbes and other small creatures as they wander around on the slide mounted below the microscope eating each other. The movement of this is surprisingly smooth: the small CNC and a well-mounted microscope means that there seems to be very little wobble or backlash as the microscope moves.

[Askewedbox] hasn’t finished yet, though: in the latest update, he adds a polarizing lens to the setup and mentions that he wants to add focus control to the system, which is controlled by a remote that comes with the microscope.

There are plenty of other things that could be added beyond that, though, such as auto pan and stitch for larger photos, auto focus stacking and perhaps even auto tracking using OpenCV to track the hideous tiny creatures that live in the microscopic realm. What would you do to make this even cooler?

2023 Halloween Hackfest: This Year’s Spooky Winners

November 20, 2023 by 1 Comment

With the zombies, ghouls, and ghosts now safely returned to their crypts until next October, it’s time to unveil this year’s winners for the 2023 Halloween Hackfest.

For this contest, sponsors DigiKey and Arduino challenged the community to come up with their best creations for what’s arguably the most hacker-friendly of holidays. Pretty much everything was fair game, from costumes to decorations. The top three winners will get $150 credit from DigiKey and some treats from Arduino — just don’t try to eat them.

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What Can You Do With Thousands Of Vintage Telephones?

November 20, 2023 by 56 Comments

Telephones. We’ve got a few around the place, and some may remember all the weird and wonderful varieties produced over the years. But, vintage phone dealers [Ron and Mary Knappen] may have a few too many. With a large 41,000 sqft property, at least three farm buildings, and no fewer than 33 semi-trailers loaded to busting with racks of phones, the retiring couple have a job sorting it all out and finding someone passionate enough to take over this once-strong business.

Technology has moved on somewhat since 1971 when they got into the retro business, and there are only so many period dramas being produced that could make a dent in a collection of a thousand steel desk phones. Nobody seems interested in taking on their business, so they are concentrating on emptying that large property in order to sell it, but the fate of the crazy number of other storage locations seems uncertain. Perhaps, other than a few museums around the world purchasing a few, this collection really is likely heading to the recyclers.

So what can we do with a vintage phone in this modern era? Here’s a primer to get you started. How about going cellular? Or maybe just add them to your existing designer collection?

Thanks to [Jeremy] and Adafruit for the tip!