The $50 Ham: Dummy Loads, Part 2

In the last installment of “The $50 Ham” I built a common tool used by amateur radio operators who are doing any kind of tuning or testing of transmitters: a dummy load. That build resulted in “L’il Dummy”, a small dummy load intended for testing typical VHF-UHF handy talkie (HT) transceivers, screwing directly into the antenna jack on the radio.

As mentioned in the comments by some readers, L’il Dummy has little real utility. There’s actually not much call for a dummy load that screws right into an HT, and it was pointed out that a proper dummy load is commercially available on the cheap. I think the latter observation is missing the point of homebrewing specifically and the Hackaday ethos in general, but I will concede the former point. That’s why at the same time I was building L’il Dummy, I was building the bigger, somewhat more capable version described here: Big Dummy.

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Hackaday Podcast Ep19: Extreme Clock Accuracy, Mobius Gears and Planetary Stunts, Jamming All Fobs, Pi in Your Wii

Join Mike Szczys and Elliot Williams as they riff on the coolest hacks from the past week. Clocks and 3D printing seem to keep coming up this week as we look at using an FPGA plus GPS receiver for better accuracy than we’re used to, and we haggle over what to call the robot arms that nudge the hands on a shelf-clock. There’s a wicked 3D-printed planetary gear design, and brackets that turn flat cardboard into boxes (more useful than you might think). We close out with great reads on the Supermicro fallout of the last 7 months, and a pretty big oops-moment as a hacker knocks out keyfobs for an entire neighborhood.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (48 MB of sweet, sweet audio)

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Continue reading “Hackaday Podcast Ep19: Extreme Clock Accuracy, Mobius Gears and Planetary Stunts, Jamming All Fobs, Pi in Your Wii”

Fun With Negative Resistance II: Unobtanium Russian Tunnel Diodes

In the first part of this series, we took a look at a “toy” negative-differential-resistance circuit made from two ordinary transistors. Although this circuit allows experimentation with negative-resistance devices without the need to source rare parts, its performance is severely limited. This is not the case for actual tunnel diodes, which exploit quantum tunneling effects to create a negative differential resistance characteristic. While these two-terminal devices once ruled the fastest electronic designs, their use has fallen off dramatically with the rise of other technologies. As a result, the average electronics hacker probably has never encountered one. That ends today.

Due to the efficiencies of the modern on-line marketplace, these rare beasts of the diode world are not completely unobtainable. Although new-production diodes are difficult for individuals to get their hands on, a wide range of surplus tunnel diodes can still be found on eBay for as little as $1 each in lots of ten. While you’d be better off with any number of modern technologies for new designs, exploring the properties of these odd devices can be an interesting learning experience.

For this installment, I dug deep into my collection of semiconductor exotica for some Russian 3И306M gallium arsenide tunnel diodes that I purchased a few years ago. Let’s have a look at what you can do with just a diode — if it’s the right kind, that is.

[Note: the images are all small in the article; click them to get a full-sized version]

Continue reading “Fun With Negative Resistance II: Unobtanium Russian Tunnel Diodes”

2019 Cornell Cup Winners Include Autonomous Boat, Flapping UAV, and Leaping Rover

For college-aged engineers and designers, finding a problem they’re truly passionate about early on could very well set the trajectory for an entire career. This is precisely the goal of the Cornell Cup, a competition that tasks applicants with solving a real-world problem in a unique and interesting way. From what we saw this is definitely working, as teams showed up with ornithopter-based quadcopters, robotic dinghies, forest fire sniffers, and high-jumping rovers.

With such an open ended approach, individual entries have a tendency to vary wildly, running the gamut from autonomous vehicles to assistive technology. No team feels pressured to pursue a project they aren’t truly invested in, and everyone’s the better for it.

Given such lofty goals, Hackaday was proud to sponsor the 2019 Cornell Cup. Especially as it so closely aligns with the product design focus of this year’s Hackaday Prize. Designing something which solves a real-world problem is definitely part of the formula when the goal is to reach large scale production. And after seeing the entries first-hand during the Finals at Kennedy Space Center, we think every one of them would be a fantastic entry into the Hackaday Prize.

I don’t envy the judges who ultimately had to narrow it down to just a few teams to take home their share of the nearly $20,000 awarded. Join me after the break for a closer look at the projects that ended up coming out on top.

Continue reading “2019 Cornell Cup Winners Include Autonomous Boat, Flapping UAV, and Leaping Rover”

This Saturday: Meetup with Hackaday, Tindie, and Kickstarter

If you’re near San Francisco this weekend, this is what you should be doing. It’s The 6th Annual Hackaday x Tindie MFBA Meetup w/ Kickstarter.

Come hang out with the hardware hackers and bring along a project of your own to get the conversation going. We’re excited to move to a new, larger venue this year. All the good of the past five years will come along with us, plus many benefits of exclusively booking out an entire venue. You can catch up with people who have been on their feet all day running booths — and usually see the stuff they can’t show you at the Faire. The crew from Hackaday, Tindie, and Kickstarter will be on hand. And you’ll get a glimpse of a lot of the cool people and projects you’ve admired on the pages of Hackaday over the years. It’s fun, you should go!

First beer is on us if you RSVP using the link at the top of this article. But we’re mainly publishing this today to show off the poster art. Deposit your adoration for this exquisite illustration in the comments below.

Amazing Art by Joe Kim

We love all of the original art that Joe Kim creates for Hackaday articles. It’s impossible to look at his poster for this event and be anything but overjoyed. Here’s a link to the full size image, but be warned that the file is 14.4 MB

This Week in Security: Backdoors in Cisco Switches, PGP Spoofing in Emails, Git Ransomware

Some switches in Cisco’s 9000 series are susceptible to a remote vulnerability, numbered CVE-2019-1804 . It’s a bit odd to call it a vulnerability, actually, because the software is operating as intended. Cisco shipped out these switches with the same private key hardcoded in software for all root SSH logins. Anyone with the key can log in as root on any of these switches.

Cisco makes a strange claim in their advisory, that this is only exploitable over IPv6. This seems very odd, as there is nothing about SSH or the key authentication process that is IPv6 specific. This suggests that there is possibly another blunder, that they accidentally left the SSH port open to the world on IPv6. Another possibility is that they are assuming that all these switches are safely behind NAT routers, and therefore inaccessible through IPv4. One of the advantages/disadvantages of IPv6 is that there is no NAT, and all the network devices are accessible from the outside network. (Accessible in the sense that a route exists. Firewalling is still possible, of course.)

It’s staggering how many devices, even high end commercial devices, are shipped with unintentional yet effective backdoors, just like this one. Continue reading “This Week in Security: Backdoors in Cisco Switches, PGP Spoofing in Emails, Git Ransomware”

IoT for Agriculture Hack Chat with Akiba

Join us Wednesday at 5:00 PM Pacific time for the IoT and Agriculture Hack Chat with Akiba!

Note the different time than our usual Hack Chat slot! Akiba willi be joining us from Japan.

No matter what your feelings are about the current state of the world, you can’t escape the fact that 7.7 billion humans need to be fed every day. That means a lot of crops to grow and harvest and a lot of animals to take care of and bring to market. And like anything else, technology can make that job easier and more productive.

join-hack-chatTo test concepts at the interface between technology and agriculture, Akiba has developed HackerFarm, a combination of homestead, hackerspace, and small farm in Japan. It’s a place where hackers with agriculture-related projects can come to test ideas and collaborate with other people trying to solve the problems of a hungry world by experimenting on an approachable scale with open-source technology.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, May 15 at 5:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.