Cockpit Instrument Respectfully Retasked As A Clock

December 5, 2023 by 3 Comments

How do you convert an old cockpit instrument into a clock? Easy: just build a circuit that convinces it it’s in the air, and the rest will take care of itself.

Now obviously, little about [porkfreezer]’s conversion of King KI 266 DME into a clock was actually easy; working with avionics rarely is. DME stands for “Distance Measuring Equipment,” an instrument that’s part of the radio navigation suite of many aircraft. DME measures the line-of-sight distance of a plane to a ground station by measuring the time it takes for a signal to return after the plane interrogates it. The plane-mounted equipment includes a UHF transceiver and a display for the cockpit instrument panel, which accepts an analog voltage signal from the transceiver and translates it into a readout on the nice Panaplex digital display.

Rather than gutting the thing and just driving the display directly, [porkfreezer] decided to build a circuit to generate the proper signals for the DME. The board uses a PIC16 and an MCP47C dual 10-bit digital-to-analog converter to generate the voltages needed, while a USB-powered DC-DC converter provides the ±15 volt supply the DME display expects.

Everything lives on a PCB that fits right on the back of the instrument. Sadly, the connector needed to mate up to the one on the instrument was outlandishly expensive — again, avionics — so [porkfreezer] had to solder the board directly to the DME’s pins. Otherwise, this would have been a completely reversible hack.

Still, it’s an interesting reuse of an unusual piece of gear, and one that respects the original design as much as possible. That counts as a win in our book.

A bald white man stands behind a table with an Apple II, a large green PCB, and a modular purple and black development board system. Atop the Apple II is what appears to be a smaller Apple II complete with beige case and brown fake keyboard.

Mini Apple IIe Now Fully Functional

December 5, 2023 by 1 Comment

Here at Hackaday, we love living in a future with miniaturized versions of our favorite retrocomputers. [James Lewis] has given us another with his fully functional Apple IIe from the Mega II chip.

When we last checked in on the Mega IIe, it was only just booting and had a ways to go before being a fully functional Apple II. We really love the modular dev board he designed to do the extensive debugging required to make this whole thing work. Each of the boards is connected with jumper pins, which [Lewis] admits would have been better as edge connectors since he should’ve known he’d be unplugging and replugging them more than he’d like.

A set of PCBs sits on a table. There is a logic analyzer plugged into one end that looks like a grey square. Three boards stick up at right angles from the main plane which consists of a purple square PCB with the IIe ROM and MEGA chips and a black rectangular PCB with four sets of headers for PCB modules to slot into.

This modular prototyping system paid dividends late in the project when a “MEGA bug” threatened the stability of the entire system. Since it was confined to the keyboard PCB, [Lewis] was able to correct the error and, swapping for the third revision of the board, everything that had been crashing the system now ran.

There were still some issues going to the final unified PCB that nearly made him give up on the project, but perseverance paid off in the end. Combining vintage chips and multiple RP2040s isn’t for the feint of heart.

Now that you have a more conveniently-sized Apple II, why not teach it some new tricks like digital photography or ChatGPT?

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Finally! A Typeface For Hardware People

December 4, 2023 by 11 Comments

When it comes to novelty typefaces there is no shortage of weird and wonderful fonts to be found when you have finally tired of Comic Sans. Everything from bananas forming letters to Wild West saloon lettering can be yours, plus of course our favourite, the embossed Dymo label. But there’s a new kid on the novelty typeface block, and for us it sweeps all before it.

Scopin’ Sans is as its creator [Guy Dupont] calls it “A typeface for hardware people”, and its party trick is that it doesn’t produce letters. Instead it forms an oscilloscope trace that displays what it would look like as serial data. Instantly your text jumps straight to 1337, and you win the internet.

We have shamefacedly to admit that we don’t know binary ASCII by sight, so we’ll have to take his word for it. But for the curious there’s a demo from which you can amuse yourself creating traces, and if you can’t recognize serial ASCII then the chances are few of the people around you can either. We take our hats off to [Guy], and it’s something we’re sure we’ll use at some point to delight and confuse our friends. It’s not the first font we’ve brought you, here are some more if you come from the bitmap era.

Better 3D Printing Overhangs? Dive! Dive!

December 4, 2023 by 28 Comments

If you want better 3D-printed overhangs, you need better cooling, right? What would be better for cooling than printing submerged in water? It turns out [CPSdrone] tried it, and, at least for overhangs, it seems to work pretty well. Check it out in the video below.

Of course, there are some downsides. First, the parts of the 3D printer don’t want to work in water. The guys used deionized water to minimize water conductivity and also sealed open connections. Some components were replaced with equivalents that were less likely to corrode. However, the bearings in the stepper are still going to corrode at some point.

There’s no free lunch, though. Cooling is good for some parts of 3D printing. But for the hot parts, it could cool down too much. They encased the hot end in a large silicon block to help prevent this. They also potted the controller board, which works but makes future maintenance and upgrades painful. Initial tests looked promising.

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Stereoscopic Macro Lens Shows Two Is Better Than One

December 4, 2023 by 10 Comments

You’d be forgiven if you thought [Nicholas Sherlock’s] new lens design was a macro lens that was 3D printed. In fact, it is, but it is also a macro lens that takes 3D images using two different cameras. If you have a pair of Sony E/FEs, you can 3D print your own copy today. If you don’t, you might have to adjust the design or wait for future releases. In any event, you are sure to enjoy the example photos, and there’s a video review of the device you can watch below.

The design merges two 4x microscope lenses to provide a 2X stereo image with a 5mm baseline. As you might expect, the secret is a prism in the assembly that allows one camera to shoot directly at the subject and the other to shoot with a 5mm offset. This is trickier than you might think because the cameras shift the image some, also.

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Powering A Cavity Magnetron, From A Battery

December 4, 2023 by 47 Comments

While vacuum electronic devices have largely been superseded over much of consumer electronics, there’s one place where they can still be found for now. The cavity magnetron is a power RF oscillator device in which electrons are induced to move in a circular path through a tuned cavity, inducing a high-power RF field, and it lies at the heart of a domestic microwave oven. They usually need a high-voltage mains transformer and a rectifier to work, but [Hyperspace Pirate] has managed to make a solid-state power supply to power one from a 12 volt battery. Better still, he’s put the resulting combo in a Care Bears lunchbox. Take a look at the video below the break.

The video starts with a potted history of the magnetron before looking at the circuit of a typical oven, which uses a single diode and a capacitor in a simple voltage multiplier. The capacitor value is adjusted to lower the power output, and a pretty thorough job is done of characterising the circuit.

The low-voltage supply starts with an XVS inverter to make the high voltage via another multiplier, but the interesting part comes with the magnetron’s heater. It’s designed for 50 or 60Hz household electricity, but there it’s receiving 40 kHz and has an appreciable impedance. The addition of a capacitor soon restores it to a reasonable performance.

In case you noticed that the ZVS converter might be improved upon, take a look at a flyback converter. Meanwhile, we should probably echo the safety message in the video that playing with magnetrons and their associated transformers can be a nasty way to die. Please take care out there!

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Retrotechtacular: The Story Of Turpentine

December 4, 2023 by 33 Comments

If someone in 2023 has ever had much call to use turpentine, chances are good it was something to do with paint or other wood finishes, like varnish. Natural turpentine is the traditional solvent of choice for oil paints, which have decreased in popularity with the rise of easy-to-clean polymer-based paints and coating. Oh sure, there are still those who prefer oil paint, especially for trim work — it lays up so nice — but by and large, turpentine seems like a relic from days gone by, like goose grease and castor oil.

It wasn’t always so, though. Turpentine used to be a very big deal indeed, as shown by this circa 1940 documentary on the turpentine harvesting and processing industry. Even then it was only a shadow of its former glory, when it was a vital part of a globe-spanning naval empire and a material of the utmost strategic importance. “Suwanee Pine” shows the methods used in the southern United States, where fast-growing pines offer up a resinous organic gloop in response to wounds in their bark. The process shown looks a lot like the harvesting process for natural latex, with slanting gashes or “catfaces” carved into the trunks of young trees, forming channels to guide the exudate down into a clay collecting cup.

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