Ask Hackaday: Split Rail Op Amp Power Supply

Water cooler talk at the office usually centers around movies, sports, or life events. Not at Hackaday. We have the oddest conversations and, this week, we are asking for your help. It is no secret that we have a special badge each year for Supercon. Have you ever wondered where those badges come from? Sometimes we do too. We can’t tell you what the badge is going to be for Supercon 2023, but here’s a chance for you to contribute to its design.

What I can tell you is that at least part of the badge is analog. Part, too, is digital. So we were discussing a seemingly simple question: How do we best generate a bipolar power source for the op amps on a badge? Like all design requests, this one is unreasonable. We want:

  • Ideally, we’d like a circuit to give us +/- 9 V to +/- 12 V at moderately low current, say in the tens of milliamps. Actual values TBD.
  • Low noise: analog circuitry, remember?
  • Lightweight: it is going on a badge
  • Battery operated: the badge thing again
  • Cheap: we only have a couple bucks in the budget for power
  • Available in quantity: we’ll need ~600 of these

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An orange m5stickc plus strapped to a wrist in the foreground with the persons other hand pressing down on the top of an installed hat, communicating with another m5stickc plus in the background on the table.

M5StickC Turned Wearable Morse Code Trainer

Have you ever felt the options for Morse code communication were too limited? Well, look no further than [marsPRE]’s open source WristMorse communicator that can connect over WiFi, can act as a Bluetooth keyboard or just be used as a Morse Code trainer.

a 'hat' for an m5stickc plus with a single row pin header exposted, a 2.5mm jack and two capacitive touch buttons on the top and bottom of the hat.

[marsPRE] uses the M5StickC Plus as the base device and attaches a custom “hat” consisting of a 2.5 mm plug for a radio connection and two capacitive touch paddles that act as the Morse Code keyer. The add-on is housed in what looks like a custom 3D print and hangs off of the end of the M5StickC Plus, connecting the hat through an eight 0.1 inch pin header.

Using the M5StickC Plus allows [marsPRE] to focus on the software, providing different options for training, communication and even using the device as a Bluetooth keyboard. The two touch sensors allow for a semi automatic keying, with the top sensor used for long dashes and the bottom sensor used for short dashes.

[marsPRE] took inspiration from the Morserino-32 and has made the wrist morse code trainer open source software and available through GitHub for anyone wanting to take a look. Morse code may an old encoding method but it’s one that’s worthy of respect. You never know when you might need to send a message from your dreams or to translate spoken word Morse code.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Music Typewriter

This edition’s community build comes from the Yes They Could, But Should They Have? file. Well, I ultimately say yes, this is intriguing. Redditor [dj_edit] looked at the venerable Model M and thought, this buckling-spring masterpiece can yet be improved upon. Yeah! Well, to each their own. I must say that it does sound great, especially with the solenoid feedback enabled via rotary encoder. Just check out the typing test.

To be clear, this is essentially a new keyboard that fits inside a Model M case, but that alone is quite a feat, especially if you consider the curvature of the backplate. Because of this hurdle, [dj_edit] went with 1 mm FR4 for the switch PCB, which is a nice compromise of sturdiness and flexibility.

Underneath those stunning reproduction keycaps are Kailh box white switches, which are pretty chonky-sounding on their own. But turn on that sweet solenoid action and you really get noisy.

Those box whites are sitting in hot-swap sockets, a design decision that kind of made things difficult because of the curvature. [dj_edit] ended up using an acrylic plate that gets bent to match the curvature by the switches themselves.

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Read Comic Books On The Commodore 64 With StripStream

Comic books are traditionally printed on paper, either as regular saddle-bound issues or in hardcover compilations. If you wanted to read them on a low-resolution screen run by an 8-bit computer, you were usually out of luck. Until now! Enter StripStream, the comic book reader for the Commodore 64.

StripStream runs on a stock PAL C64 system, using the Datasette interface. A PC program is used to compose a comic into a suitable format for the C64. It then generates a .TAP file which can either be played in a C64 emulator, or recorded onto an audio tape for loading on real hardware.

According to [janderogee], who created the software, just 34 minutes of tape can store over 300 images and 1200 lines of subtitle text. Cassettes were chosen for the storage method as standard 5 1/2″ C64 disks could only hold 165 kilobytes of data per side, meaning two whole double-sided disks would be needed to store the same amount of data. Plus, the linear nature of tape makes sense for a sequentially-read comic story. Just don’t get any ideas about doing a choose-your-adventure thing here, as StripStream isn’t built for random access.

If you don’t want to read regular comics, you can always use a tool to automatically generate them from existing media. Incidentally, StripStream is a great name, but we would have called it Comicdore 64.

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Soft Robotic System For In Situ 3D Bioprinting And Endoscopic Surgery

The progress of medical science has meant increasingly more sophisticated ways to inspect and repair the body, with a shift towards ever less invasive and more effective technologies. An exciting new field is that of in situ tissue replacement in a patient, which can be singular cells or even 3D printed tissues. This in vitro approach of culturing replacement tissues comes however with its share of issues, such as the need for a bioreactor. A more straightforward approach is printing the cells in vivo, meaning directly inside the patient’s body, as demonstrated by a team at the University of New South Wales Sydney with a soft robot that can print layers of living cells inside for example a GI tract.

In their paper, the team — led by [Dr Thanh Nho Do] and PhD student [Mai Thanh Thai] — describe the soft robot that is akin to a standard endoscope, but with a special head that has four soft microtubule artificial muscles (SMAM) for three degrees of freedom and fabric bellow actuators (FBA) that provide the motion desired by the remote controller. The system is configured in such a way that the operator inputs the rough intended motions, which are then smoothed by the software before the hydraulics actuate the head.

In a test on a simulated GI tract, the researchers were able to manipulate a prototype, and deposit a range of materials from the installed syringes. They envision that a system like this could be used as with endoscopes and laparoscopy to not only accurately deposit replacement cells inside the patient’s body, but also to perform a range of other surgical interventions, whereby the surgeon is supported by the system’s software, rather than manipulating the instruments directly.

A Look At Sega’s 8-Bit 3D Glasses

From around 2012 onwards, there was a 3D viewing and VR renaissance in the entertainment industry. That hardware has grown in popularity, even if it’s not yet mainstream. However, 3D tech goes back much further, as [Nicole] shows us with a look at Sega’s ancient 8-bit 3D glasses [via Adafruit].

[Nicole]’s pair of Sega shutter glasses are battered and bruised, but she notes more modern versions are available using the same basic idea. The technology is based on liquid-crystal shutters, one for each eye. By showing the left and right eyes different images, it’s possible to create a 3D-vision effect even with very limited display hardware.

The glasses can be plugged directly into a Japanese Sega Master System, which hails from the mid-1980s. It sends out AC signals to trigger the liquid-crystal shutters via a humble 3.5mm TRS jack. Games like Space Harrier 3D, which were written to use the glasses, effectively run at a half-speed refresh rate. This is because of the 60 Hz NTSC or 50 Hz PAL screen refresh rate is split in half to serve each eye.  Unfortunately, though, the glasses don’t work on modern LCD screens, as their inherent display lag throws off the timing of the pulses the console sends to the glasses.

It’s a neat look at an ancient bit of display tech that had a small resurgence with 3DTVs in the 2010s. By and large, it seems like humans just aren’t that into 3D, at least beneath a full-VR experience. Meanwhile, if you’re wondering what 8-bit 3D looked like, we’ve got a 3D video (!) after the break.

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Water Solves Mazes, Why Not Electrons?

A few weeks ago, we looked at a video showing water “solving” a maze. [AlphaPhoenix] saw the same video, and it made him think about electrons “finding the path of least resistance.” So can you solve a maze with foil, a laser cutter, a power supply, and some pepper? Apparently, as you can see in the video below.

At first, he duplicated the water maze, but without the effect of gravity. It was hard to see the water flow, so pepper flakes made the motion of the liquid quite obvious. The real fun, though, started when he cut the maze out of foil and started running electrons across it.

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