Ham Radio Gets Brain Transplant

Old radios didn’t have much in the way of smarts. But as digital synthesis became more common, radios often had as much digital electronics in them as RF circuits. The problem is that digital electronics get better and better every year, so what looked like high-tech one year is quaint the next. [IMSAI Guy] had an Icom IC-245 and decided to replace the digital electronics inside with — among other things — an Arduino.

He spends a good bit of the first part of the video that you can see below explaining what the design needs to do. An Arduino Nano fits and he uses a few additional parts to get shift registers, a 0-1V digital to analog converter, and an interface to an OLED display.

Unless you have this exact radio, you probably won’t be able to directly apply this project. Still, it is great to look over someone’s shoulder while they design something like this, especially when they explain their reasoning as they go.

The PCB, of course, has to be exactly the same size as the board it replaces, including mounting holes and interface connectors. It looks like he got it right the first time which isn’t always easy. Does it work? We don’t know by the end of the first video. You’ll have to watch the next one (also below) where he actually populates the PCB and tests everything out.

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Perovskites Understood

The usual solar cell is made of silicon. The better cells use the crystalline form of the element, but there are other methods to obtain electric energy from the sun using silicon. Forming silicon crystals, though, can be expensive so there is always interest in different solar technologies. Perovskite is one of the leading candidates for supplanting silicon. Since they use lead salts, they are cheap and simple to construct. The efficiency is good, too, even when the material is not particularly well ordered. The problem is every model science has on what should make a good solar cell predicted that orderly compounds would perform better, even though this is not true for perovskite. Now scientists at Cambridge think they know why these cells perform even in the face of structural defects.

Perovskites take their name from a natural mineral that has the same atomic structure. In 2009, methylammonium lead halide perovskites were found to act as solar cells. Conversion rates can be as high as 25.5% according to sources and — apparently — the cells could be as much as 31% efficient, in theory. Solar cells top out — again, in theory — at 32.3% although in the real world you are lucky to get into the high twenties.

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Build Your Own HP41C

There was a time when engineers carried slide rules. Then there was a time when we all carried calculators. Sure, calculators are still around, but you are more likely to use your phone. If you really need serious number crunching, you’ll turn to a full computer. But there was that awkward time when calculators were very important and computers were very expensive that calculators tried to be what we needed from full-blown computers. The HP41C was probably the pinnacle of that trend. If you’ve ever had one, you know that is a marvel of the day’s technology with alphanumeric capabilities and four plug in ports for more memory or ROMs. It really was a little hand-held computer. Didn’t have one? Don’t worry, you can now build your own. In fact, the HP emulator will also act like an HP15C or 16C, if you prefer.

You can see the device in action in the video below. As you might expect, this version uses a through-hole ATMEGA328 and even at 8 MHz, the emulation is faster than the original calculator. The machine also has over double the memory the original calculator had along with a real-time clock built-in. The display is also backlit, something we all wanted in the original.

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DIY High Flow 3D Printing Nozzle

Sometimes advances happen when someone realizes that a common sense approach isn’t the optimal one. Take radio. Success in radio requires bigger antennas and more power, right? But cell phones exist because someone realized you could cram more people on a frequency if you use less power and smaller antennas to limit the range of each base station. With FDM 3D printing, smaller nozzles were all the rage for a while because they offer the possibility of finer detail. However, these days if you want fine detail you should be using resin-based printers and larger nozzles offer faster print times and stronger parts. The Volcano hotend started this trend but there are other options now. [Stefan] over at CNC Kitchen decided to make his own high flow nozzle and he claims it is better than other options.

Don’t get too carried away with the DIY part. As you can see in the video below, he starts with a standard nozzle, so it is really a nozzle conversion or hack. The problem with high flow isn’t the hole in the nozzle. It is melting the plastic fast enough. The faster the plastic moves through the nozzle, the less time there is for it to melt.

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A PDP 11 By Any Other Name: Heathkit H11 Teardown And Repair

[Lee Adamson] is no stranger to classic computers. He recently picked up a Heathkit H11A which, as you might remember, is actually a PDP-11 from DEC. Well, technically, it is an LSI-11 but still. Like a proper LSI-11, the computer uses the DEC QBus. Unlike a lot of computers of its day, the H11 didn’t have a lot of switches and lights, but it did have an amazing software library for its day.

[Lee] takes us through a tour of all the different cards inside the thing. It is amazing when you think of today’s laptop motherboards that pack way more into a much smaller space. He also had to fix the power supply.

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Arduino Plays The Glasses

Have you ever been on a city street and seen a busker playing music on glasses? Each glass has a different amount of water and produces a different note when tapped. [Cyberlab] must have seen them and created an Arduino robot to play tunes on glasses. You can see the result in the video below.

If we had done this, we might have had a solenoid per glass or used some linear component like a 3D printer axis to pick different glasses. [Cyberlab] did something smarter. The glasses go in a circle and a stepper motor points at the correct glass and activates a solenoid. The result is pretty good and it is a lot simpler than any of our ideas.

If you aren’t musically inclined, you might wonder how you’d program the songs. There’s an example of taking a music box score from a website — apparently, there are lots of these — and removing any polyphony from it. The site mentioned even has an editor where you can import MIDI files and work with them to produce a music box strip that you could then convert. Then you encode each note as a number from 0 to 6.

Of course, you also have to fill your glasses with the right amount of water. A piano tuning phone app should be useful. We’ve seen this done in a linear fashion before. You can even use a single glass for many notes with a little ingenuity.

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The (Sodium Chloride) Crystal Method

[Chase’s] post titled “How to Grow Sodium Chloride Crystals at Home” might as well be called “Everything You Always Wanted to Know about Salt Crystals (but Were Afraid to Ask).” We aren’t sure what the purpose of having transparent NaCl crystals are, but we have to admit, they look awfully cool.

Sodium chloride, of course, is just ordinary table salt. If the post were simply about growing random ugly crystals, we’d probably have passed over it. But these crystals — some of them pretty large — look like artisan pieces of glasswork. [Chase] reports that growing crystals looks easy, but growing attractive crystals can be hard because of temperature, dust, and other factors.

You probably have most of what you need. Table salt that doesn’t include iodine, a post, a spoon, a funnel, filter paper, and some containers. You’ll probably want tweezers, too. The cooling rate seems to be very important. There are pictures of what perfect seed crystals look like and what happens when the crystals form too fast. Quite a difference! Once you find a perfectly square and transparent seed crystal, you can use it to make bigger ones.

After the initial instructions, there is roughly half the post devoted to topics like the effect growth rate has on the crystal along with many pictures. There are also notes on how to form the crystals into interesting shapes like stars and pyramids. You can also see what happens if you use iodized salt.

If salt is too tame for you, try tin. Or opt for copper, if you prefer that.