Mysterious Files PH

If you’ve got a cheap ham rig, it might not be very practical for you to receive certain transmissions out of the box. However, if you were to hack in a convenient little beat frequency oscillator (BFO) to your rig, then you’d be up and running. Here’s a simple way to do just that with a venerable old part everybody knows and loves.

The build in question concerns the use of a 555 timer IC. It’s seasoned with the right smattering of resistors and capacitors to taste, producing a 455 kHz beat frequency oscillator. This can be injected into the intermediate frequency chain of a receiver, making up for the lack of a steady carrier wave when receiving continuous-wave and single side-band suppressed carrier transmissions. Thanks to a potentiometer in the circuit, it’s tunable, too, from 455 kHz, plus or minus twenty percent or so. Thanks to the versatility of the 555, it’s possible to run the chip on a wide voltage range, anywhere from 4.5 volts to 16 volts, which makes it easy to install in just about any old radio set without requiring adding a specialized power supply. There’s also an alternative design that EDN covered in greater detail some time ago.

If you’re eager to dive into a wider range of transmissions than your radio can currently receive, this old-school ham hack could be just what the shack ordered. We feature plenty of good ham hacks around these parts, and don’t forget—we always want to hear about the freshest ones on the tipsline.

Would you like to make your own energy? Why, who doesn’t in this era of rising costs! A sterling engine always looks like a good fit for that: highly efficient, with no risk of a boiler explosion. A thermoacoustic sterling engine looks even better, since it has only one moving part at the output end. A thermoacoustic sterling engine you can 3D print yourself looks best of all, and that’s what [my engines] has on offer, now that even the burner and hot end of his thermoacoustic engine are designed for SLA metal printing.

We previously reported on the open-source engine, but there’ve been some improvements worth talking about. For one thing, he’s integrated a biogas/methane burner directly inside the 3D-printable hotend. For another, that 3D-printed design allows for an excellent heat exchange geometry that would be very hard to get any other way. The whole thing is open source with plans available at OwnEnergy.org, where you can find links to the apparently-mandatory Discord channel and now an old-style forum to actually collaborate on the design, which is open-source. The site is also now the home of all data and discussion about [my engines]’s homescale biogas plant, which is the power source for this little engine.

If you’d rather print a combustion engine, you can do that, too, but you’ll need more “vitamins” than this unit requires.

[Makestreme] had always wanted to own a nice telescope, but found that budget would not stretch to anything above a cheap model with a limited 50 mm aperture. Wanting a better view of the heavens, the way forward was obvious—it was time to build a better telescope, instead!

The build is based around a 114 mm diameter mirror sourced from Amazon. It’s assembled inside a length of 5-inch PVC pipe of just under a meter to suit the 900 mm focal length of the concave reflector. 3D printed components are used to mount the mirror and control its position for proper focus and collimation. Traditionally, a reflector based telescope would use a mirror and eyepiece to provide a view to the user. However, [Makestreme] built this as a smart telescope, instead integrating a Raspberry Pi Camera Module 3 at the focal point. It’s connected to a Raspberry Pi Zero 2W, running off an 18650 lithium-ion cell and a 5 V boost module for portability. The Pi runs a Python script that hosts a small web server allowing access to the live camera feed along with controls for brightness, exposure, and gain. [Makestreme] then uses apps like SkyMap and SkEye to help aim the telescope at astronomical elements of interest.

If you’ve ever wanted to explore the heavens from down on Earth, building your own telescope is a great way to start. A camera-based build like this one can be a bit simpler than traditional builds, too, without the fuss of having to install an eyepiece.

In this week’s episode, Hackaday Editors Elliot Williams and Tom Nardi start things off by getting excited about the recently announced 2026 Retrocomputing Challenge. From there the conversation will cover efforts to improve desktop 3D printing with lasers, an expensive grill with an ESP32 controller and an open source firmware, open source tools underground, and some impressive techniques to squeeze a bit more utility out of the common QR code.

You’ll also hear about turning PVC pipes into flat stock, old school Radio Shack electronic kits, and VR soldering demos. Stick around to the end of the episode learn about the latest developments in over-the-counter hearing aids and the 1-bit CPU that’s enjoying an unexpected fandom nearly 50 years after its release.

Check out the links if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download in DRM-free MP3.

Episode 383 Show Notes:

Mailbag:

• Alexander wrote in praise of buying ultrasonic knife guts. Donald Papp wrote up his experience with a hacked dental tool a few years back. Now you can get it over the counter.
• Joey wrote in asking if we can add video/visuals to the Podcast. We complain about how difficult that would be.  :)
• Mailbag still needs intro/outro music. Anyone want to whip something up? Send it to mailbag@hackaday.com.

News:

• Announcing The 2026 Hackaday Retrocomputing Challenge
• Using The Famicom Network System In 2026

Interesting Hacks of the Week:

• Laser Layers For (Almost) Isotropicly Strong Prints
  • 3D Print Smoothing, With Lasers
  • More On Wave Overhangs For 3D Printing
• Reverse Engineered Grill Controller Gets Open Firmware
• Hackaday Europe 2026: Open Source Hardware Goes Underground, Literally
  • GitHub – furbrain/STIC · GitHub
• Building Custom Backyard Solar Lights
  • PVC Pipe Transformed Into Handy Tool Box
• Compress Links For Optimal QR Codes
  • http://ha.mr#2)22
  • Store Tunes On Paper And Stream Them Over LoRA
• Radio Shack Toy Returns To Life

Quick Hacks:

• Elliot’s Picks:
  • Joy-Cons Plus WiiMotes Make For Switch 2 Wii-Cons
  • So, You Want To Fix An Old Camera
  • Watch Soldering Up Close And From Any Angle, In VR
  • May This Balloon Banjo Resonate With You
• Tom’s Picks:
  • Snooping Flume Water Monitor Data On The Wire
  • Smarting Up A Doorbell With Zigbee
  • Scanning For Lifesigns With ESP32 And Raspberry Pi

Can’t-Miss Articles:

• Smartphones And The Next Generation Of Hearing Aids
• Hackaday Europe 2026: The 1-Bit CPU That Ran Factories
  • Building An Industrial Control Unit With An Industrial Control Unit
  • A one-bit processor explained: reverse-engineering the vintage MC14500B
  • WDR-1-Bit-Computer
  • Too Cool For 8-bit Retro? Try 1-bit Gaming

These days, modems are pretty fancy bits of kit, what with to keep up with the speeds of cable, VDSL, and fiber connections. At lower speeds, though, it’s entirely possible to build a modem out of simple discrete components. [sv3ora] did just that, building a simple modem for the CB2 Micro.

The project takes advantage of the fact that the V1.54 firmware for the CB2 Micro enabled 75 baud serial communication. Thus, it made sense for [sv3ora] to build a 75 baud modem to suit. As was the way in the days of dial-up internet, the modem modulates data into audio, demodulates audio back into data, allowing the CB2 Micro to send and receive data over telephone lines, ham radio links, or to store and retrieve data via mediums like cassette tape.

The device is built out of good old BC547 transistors. along with a smattering of diodes, resistors, and capacitors as supporting hardware. That’s all you need to turn slow serial into audio and back again. [sv3ora] does a great job of demoing the hardware, using it to store a program on tape and retrieve it again later.

We love old school modems around these parts. We’ve even explored ways to build your own dial-up ISP in the past!

The Peripheral Component Interconnect (PCI) bus was first introduced all the way back in 1992. It quickly became the standard way to interface add-on cards on the PC platform, supplanting earlier buses like ISA and various other oddball standards. You wouldn’t expect to see a PCI bus on a Motorola-based machine, but [maniek86]’s homebrew rig offers just that. 

This computer is a beautiful piece of homebrew engineering, constructed out of protoboard and loose wires rather than any fancy PCB. At the heart of the build lies a Motorola 68000 running at 10 MHz. It’s got 1 MB of SRAM, 4 KB of ROM, and a MC68681P acting as a UART, timer source, and I/O controller. Where things get special, though, is in the inclusion of a Xilinx Spartan II FPGA (XC2S100), which acts as a PCI bridge. It provides the machine with two 32-bit 5-volt PCI slots which are interrupt capable, albeit with no bus mastering. A XC95144XL CPLD also sits present to act as glue logic to help lace everything together.

[maniek86] does a great job of explaining exactly why the PCI bus was hard to implement, and how it was pulled off in the end. The guide also covers how the system was able to interface various cards, from a PCI serial expansion to a Cirrus VGA adapter. It’s all good stuff.

We’ve featured other work from [maniek86] before, too, like this brilliant 486-based single-board computer. Video after the break.

Much like Apple’s once vaunted super-slim butterfly keyboard, today’s range of portable devices featuring flexible OLED displays – which can fold said display into a much smaller form factor – are a marvel of engineering.

Unfortunately engineering can only do so much against fundamental flaws. In the case of both these flexible OLEDs and butterfly keyboards the main issue is that of dust intrusion, with a recent teardown by [iFixit] going over the reasons for this.

As test subject we got a Galaxy Z Fold 8, as an example of a modern-day foldable smartphone-tablet hybrid. This phone has an IP48 rating, meaning that it’s water-resistant, but not dust-resistant for particles smaller than 1 mm. To test this, [iFixit] used UV-reactive dust particles, making sure that they got literally everywhere inside the phone’s hinge mechanism.

After this treatment, trying to fold the phone caused the hinge mechanism to make absolutely horrific crunching noises, confirming that it’s reached dust-under-butterfly-keycap levels of unusable. During the subsequent teardown a quick pass with the UV lamp showed that not much of the dust had penetrated into the two halves of the device at least, but the hinge mechanism wasn’t as lucky.

Getting to the hinge is sadly rather destructive, as it involves removing the flexible OLED. Once the hinge was exposed and subjected to UV light the spectacle was something to marvel at, as can be seen in the above screenshot. With the dust caking literally every part of the mechanism, it was little wonder that the hinge had ceased to work.

Although this was obviously an extreme case of dust exposure, and the average flexible OLED screen’s hinge won’t see nearly as much dust, one can’t help but feel slightly disconcerted at that crunching noise, knowing that it’s just one big dust exposure away.