The $50 Ham: Going Mobile

So far in this series, everything we’ve covered has been geared around the cheapest and easiest possible means of getting on the air: getting your Technician license, buying your first low-end portable transceiver, and checking in on the local repeater nets. That’s all good stuff, and chances are you can actually take all three of those steps and still have change left over from your $50 bill. Like I said, amateur radio doesn’t have to be expensive to be fun.

But at some point, every new ham is going to yearn for that first “real” rig, something with a little more oomph in terms of power, and perhaps with a few more features. For many Technicians, the obvious choice is a mobile rig, something that can be used to chat with fellow hams on the way to work, or to pass the time while on long road trips. Whatever your motivation is, once you buy a radio, you have to install it, and therein lie challenges galore, both electrical and mechanical.

I recently took the plunge on a mobile rig, and while the radio and antenna were an order of magnitude more expensive than $50, the process of installing it was pretty cheap. But it’s not the price of the thing that’s important in this series; rather, it’s to show that ham radio is all about doing it yourself, even when that means tearing your car apart from the inside out and rebuilding it around a radio.

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This Box Counts Your Blessings For You

It’s that time of year again when production in Shenzhen grinds to a halt. Lunar New Year has kicked off the annual month-long Spring Festival, and the whole country has taken time off to be with family and celebrate. One tradition of Spring Festival is that everyone gives each other red envelopes with various amounts of money in them called hongbao. The point of this ‘lucky money’ is to spread good fortune in the new year, and it’s easy to amass a whole pile of hongbao by the end of the festival.

[Makerming] made this lovely counting box for anyone looking to keep track of their hongbao in style. It probably goes without saying that this would make an awesome mailbox for Valentines (or anything else that fits in the slot), but there you go. The circuit is pretty simple thanks to a Grove connector shield meant for Arduinos. An IR break-beam module detects the incoming envelope, and the Uno increments the count on the display. The wiggly, servo-driven example hongbao on top are there to add to the fun.

We love the laser-cut decoration on the front, which is an homage to the intricate paper cut decorations. If you don’t like that one, [Makerming] included design files for several other options. Watch it wiggle after the break!

If you won’t be looking to collect valentines because you’ve already found that special someone, give them something that lasts longer than chocolate or roses.

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Tipping Points In The Climate System: The Worst Kind Of Positive Feedback

With global temperatures continuing to break records in recent years, it’s important to cast an eye towards the future. While efforts to reduce emissions remain in a political quagmire, time is running out to arrest the slide into catastrophe.

Further compounding the issue are a variety of positive feedback loops that promise to further compound the problem. In these cases, initial warming has flow-on effects that then serve to further increase global temperatures. Avoiding these feedback mechanisms is crucial if the Earth is to remain comfortably livable out to the end of the century.

A Multitude of Causes

The issue of climate change often appears as a simple one, with the goal being to reduce greenhouse gas emissions in order to prevent negative consequences for human civilization. Despite this, the effects of climate change are often diffuse and intermingled. The various climate systems of the Earth interact in incredibly complex ways, and there are many mechanisms at play in these feedback effects that could tip things over the edge.

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An EV Motor Controller Home Build

Many of us will have experimented with brushless motors, and some of us will have built our own controllers rather than using an off-the-shelf part. Doing so is a good way to understand their operation, and thus to design better brushless motor powered projects. Few of us will have gone as far as [etischer] though, and embarked upon building our own controller for a 300V 90kW traction motor.

The tricky part of a high power brushless motor controller lies not in the drive but in the high-power switching arrangements. He’s using a bank of IGBTs, and to drive them he’s using a smaller industrial variable frequency drive controller with its own output transistors removed. He takes us through some of the development of the system, including showing him blowing up a set of IGBTs through having too much inductance between transistors and reservoir capacitor, and then to his final design.

This is part of a project VW first converted ten years ago, and as part of a series of videos he’s produced one going through the whole project. It’s a fascinating breakdown of the parts required for an EV conversion, and the teething troubles he’s encountered along the way.

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Serious Repair Work On The Amiga 600

The Amiga will be forever loved for bringing serious multimedia capabilities to the home computer market. However, these machines are now showing their age, and keeping them running can take a bit of work. [Drygol] isn’t one to shy away from the task, however, and set about repairing a few Amiga 600s that came his way.

First up on the docket is replacing the many electrolytic capacitors that tend to leak over the years. They can cause corrosion, destroying traces and other components, as well as failing themselves. [Drygol] is an old hand at this now, whipping out the hot air station and some copper shielding to protect delicate connectors from melting. A simple recap was enough to get one machine up and running, but the other was more recalcitrant. When swapping a dud CPU out, a pad was destroyed on the PCB. This necessitated some careful tracing, followed by a drill hole through the PCB to allow a bodge wire to run the signal from the other side of the board.

There’s also plenty of upgrades to be done; S-Video outputs instead of the crummy old RF modulator, and special interrupt switches that help when cracking games and doing assembly programming. Thanks to a rich aftermarket and vivid community, researching and performing mods is easy thanks to writeups and parts available online.

It’s a great example of the basic techniques one must master to keep old hardware on the boil. Learn to recap, refit, and hunt for problems, and you’ll be well on your way to maintaining your retro fleet for years to come. We’ve seen [Drygol]’s work before too – this vampiric A500 is a particular treat!

Writing Dance Bangers Like It’s 1990 Again

Dance and house music exploded in a big way at the end of the 1980s. Typically the product of well-equipped studios with samplers and mixers worth thousands of dollars, it was difficult for the home gamer to get involved. That was, until the advent of the glorious Amiga, as [cTrix] ably demonstrates.

Sampling on your Amiga often meant sneaking off with the family hi-fi.

The video explains the history of both the music and the hardware, and highlights just why the Amiga was so special. Packing stereo audio and a four-channel sound chip, it had the grunt to pump out the tunes. All it was lacking was an audio input – which is where third-party hardware stepped in. Parallel-port analog-to-digital converters hit the market in a big way, letting users sample audio on their home computer without breaking the bank.

[cTrix] then proceeds to demonstrate how one would go about producing a dance track on an Amiga way back in 1990. A home stereo is used to play records, hooked up to a Stereo Master parallel port sampler. With a bunch of drum, piano, and synth samples recorded and saved on disk, a tracker is then used to assemble the track. It’s then compared with other music from the era as a great example of how things used to be done.

Overall, the Amiga will long have a legacy as the machine that brought real multimedia capabilities to the home computer. It’s one of our favourites, though keeping them going can be tough sometimes. Video after the break.

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Ham Antennas From MIT

Dealing with an antenna is one of those topics we never feel like we know enough about. MIT had a live stream of [Dr. Kiersten Kerby-Patel] discussing antennas in a talk, sponsored by the ham radio club on campus. You can see the recording below.

The main assertion of the presentation is that everything is a dipole unless it is a loop. Although the professor probably deals with antennas at an extremely high theoretical level, she did a great job of keeping it aimed at ham radio operators.

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