Altair Front Panel Tutorials

If you aren’t old enough to remember when computers had front panels, as [Patrick Jackson] found out after he built a replica Altair 8800, their operation can be a bit inscrutable. After figuring it out he made a pair of videos showing the basics, and then progressing to a program to add two numbers.

Even when the Altair was new, the days of front panels were numbered. Cheap terminals were on their way and MITS soon released a “turnkey” system that didn’t have a front panel. But anyone who had used a minicomputer from the late 1960s or early 1970s really thought you needed a front panel.

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Easy-SDR Gets Updates

Back in 2018, we covered [Igor’s] Easy-SDR project that aimed to provide open hardware extensions for the chap RTL-SDR receivers. If you haven’t been there for a while, it’s worth a look as there have been many recent updates. According to the author’s Reddit post:

  1. Most of the devices are now prepared for installation in a metal case measuring 80 x 50 x 20 millimeters.
  2. There’s a completely redesigned LNA design. Now, Bias Tee powered amplifiers are housed in a 50 x 25 x 25mm metal case and have N-type connectors.
  3. There’s an added amplifier based on the PGA-103 microcircuit.
  4. Added is the ability to install filters in final amplifiers (a separate printed circuit board, depending on the filter used).
  5. A new device – SPDT antenna switch for receiving antennas.
  6. The upconverter has been redesigned. Added intermediate buffer stage between the crystal generator and mixer.
  7. RF lines in all devices were recalculated to correspond to the characteristic wave impedance of 50 Ohm.
  8. Reduced size of PI attenuator PCB.

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Cryptic Calendar Makes For A Useful Wall Ornament

Hackers love a good clock build, but its longer term cousin, the calendar, is more seldom seen in the wild. Regardless, they can be just as useful and elegant a project, as this cryptic design from [Wolfspaw] demonstrates.

The project consists of a series of rotating wheels, displaying a series of arcane symbols. When the markings on the wheel align correctly with the viewing window, they display the date, month, and day of the week, respectively. The wheels themselves are fitted with 3D printed gear rings, which are turned by stepper motors under the control of an Arduino Nano. Hall effect sensors and magnets are used to keep everything appropriately aligned, while a DS3231 real time clock handles timekeeping duties.

It’s a tidy build, and we think the cryptic design adds a little mystery, making this an excellent conversation piece. The build is actually a remix of a project we’ve featured before, scaled and given a unique twist to suit [Wolfspaw]’s own personal aesthetic. Video after the break.

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Adding Remote Control To The Elegoo Mars Pro

Recent price drops put entry level masked stereolithography (MSLA) resin 3D printers at around $200 USD, making them a very compelling tool for makers and hackers. But as you might expect, getting the price this low often involves cutting several corners. One of the ways manufacturers have made their machines so cheap is by simplifying the electronics and paring down the feature set to the absolute minimum.

So it was hardly a surprise for [Luiz Ribeiro] to find that his new Elegoo Mars Pro didn’t offer WiFi connectivity or a remote control interface. You’re supposed to just stick a USB flash drive into the printer and select the object you want to print from its menu system. But that doesn’t mean he couldn’t hack the capability in himself.

Monitoring a print with Mariner.

If this were a traditional 3D printer, he might have installed OctoPrint and been done with it. But resin printers are a very different beast. In the end, [Luiz] had to develop his own remote control software that worked around the unique limitations of the printer’s electronics. His software runs on a Raspberry Pi Zero and uses Linux’s “USB Gadget” system to make it appear as a flash drive when plugged into the USB port on the Elegoo Mars Pro.

This allows sending object files to the printer over the network, but there was a missing piece to the puzzle. [Luiz] still needed to manually go over to the printer and select which file he wanted to load from the menu. Until he realized there was an exposed serial port on control board that allowed him to pass commands to the printer. Between the serial connection and faux USB Mass Storage device, his mariner software has full control over the Mars Pro and is able to trigger and monitor print jobs remotely.

It might not offer quite the flexibility of adding OctoPrint to your FDM 3D printer, but it’s certainly a start.

Animated Pumpkins Sing And Scare On Halloween

The animated video combined with the 3D-printed prop makes for an excellent effect.

Carving Jack O’ Lanterns out of pumpkins is a favorite Hallowe’en tradition for many, but relying on candles and knives is decidedly low-tech. [Lewis] of [DIY Machines] decided to whip up something a little more animated to scare the local trick-or-treaters instead.

The build consists of 3D printed pumpkins, lit from behind with a low-cost projector. Driven by a Raspberry Pi, the projector plays video files that project animated faces onto the pumpkins. The effect is great, giving the illusion of a real anthropomorphic Jack O’ Lantern sitting on your very porch. To control the system, a series of arcade buttons are hooked up to the Raspberry Pi allowing visitors to activate a song, a scare, or a story.

It’s a fun build that is a great way to add some interactivity to your Hallowe’en decorations. If you want to take your work up a notch, consider projecting on to your whole house. Video after the break.

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The Theremin Is 100 Years Old; Celebrating The Spookiest Of Instruments

It wouldn’t be October without Halloween, and it wouldn’t be Halloween without some spooky music. There’s no instrument spookier than a Theremin, which also happens to be one of the world’s first electronic instruments.

Leon Theremin plays his namesake instrument. Image via Linda Hall Library

You’ve no doubt heard the eerie, otherworldly tones of the Theremin in various 1950s sci-fi films, or heard the instrument’s one-of-a-kind cousin, the Electro-Theremin in “Good Vibrations” by the Beach Boys. The Theremin turns 100 years old this month, so we thought we’d take a look at this strange instrument.

One hundred years ago, a young Russian physicist named Lev Sergeyevich Termen, better known as Leon Theremin, was trying to invent a device to measure the density of various gases. In addition to the standard analog needle readout, he wanted another way to indicate the density, so he devised an oscillator whistle that would change pitch based on the density.

He discovered by accident that having his hand in the field of the antenna changed the pitch of the whistle, too. Then he did what any of us would do — played around until he made a melody, then called everyone else in the lab over to check it out.

Theremin soon showed his device to Lenin, who loved it so much that he sent Lev on a world tour to show it off. While in New York, he played it for Rachmaninoff and Toscanini. In fact you can see a video recording of Leon playing the instrument, a performance that’s more hauntingly beautiful than spooky. In 1928, he patented the Theremin in the United States and worked with RCA to produce them.

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Hackaday Podcast 091: Louisville Exploder, Generating Japanese Joinery, Relay Retrocomputer Rally, And Chop The Robopup

Hackaday editors Mike Szczys and Elliot Williams dig through the greatest hacks that ought not be missed this week. There’s a wild one that flexes engineering skills instead of muscles to beat the homerun distance record with an explosively charged bat. A more elegant use of those engineering chops is shown in a CNC software tool that produces intricate wood joinery without needing an overly fancy machine to fabricate it. If your flesh and blood pets aren’t keeping up with your interests, there’s a new robot dog on the scene that far outperforms its constituent parts which are 3D-printed and of the Pi and Arduino varieties. And just when you thought you’d seen all the craziest retrocomputers, here’s an electromechanical relay based machine that took six years to build (although there’s so much going on here that it should have taken sixteen).

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 (~60 MB)

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