All-Band Radio Records Signals, Plays MP3s

May 4, 2025 by Tyler August 10 Comments

In these days of everything-streaming, it’s great to see an old school radio build. It’s even better when it’s not old-school at all, but packed full of modern ICs and driven by a micro-controller like the dsPIC in [Minh Danh]’s dsMP3 build. Best of all is when we get enough details that the author needs two blog posts — one for hardware, and one for firmware — like [Minh Danh] has done.

This build does it all: radio, MP3 playback, and records incoming signals. The radio portion of the build is driven by an Si4735, which allows for receiving both in FM and AM — with all the AM bands, SW, MW and LW available. The FM section does support RDS, though because [Minh Danh] ran out of pins on the dsPIC, isn’t the perfect implementation.

The audio section is a good intro to audio engineering if you’ve never done a project like this: he’s using a TDA1308 for headphones, which feeds into a NS8002 to drive some hefty stereo speakers– and he tells you why he selected those chips, as well as providing broken-out schematics for each. Really, we can’t say enough good things about this project’s documentation.

That’s before we get to the firmware, where he tells us how he manages to get the dsPIC to read out MP3s from a USB drive, and write WAVs to it. One very interesting detail is how he used the dsPIC’s ample analog inputs to handle the front panel buttons on this radio: a resistor ladder. It’s a great solution in a project that’s full of them.

Of course we’ve seen radio receivers before, and plenty of MP3 players, too — but this might be the first time we’ve seen an electronic Swiss army knife with all these features, and we’re very glad [Minh Danh] shared it with us.

Continue reading “All-Band Radio Records Signals, Plays MP3s” →

PCB Renewal Aims To Make Old Boards Useful Again

May 4, 2025 by Lewin Day 13 Comments

We’ve all made a few bad PCBs in our time. Sometimes they’re recoverable, and a few bodge wires will make ’em good. Sometimes they’re too far gone and we have to start again. But what if you could take an existing PCB, make a few mods, and turn it into the one you really want? That’s what “PCB Renewal” aims to do, as per the research paper from [Huaishu Peng] and the research group at the University of Maryland.

*The plugin quantifies resource and time savings made by reusing an old board.*

The concept is straightforward — PCB Renewal exists as a KiCad plugin that can analyze the differences between the PCB you have and the one you really want. Assuming they’re similar enough, it will generate toolpaths to modify the board with milling and epoxy deposition to create the traces you need out of the board you already have.

Obviously, there are limitations. You’ll never turn a PlayStation motherboard into something you could drop into an Xbox with a tool like this. Instead, it’s more about gradual modifications. Say you need to correct a couple of misplaced traces or missing grounds, or you want to swap one microcontroller for a similar unit on your existing board. Rather than making brand new PCBs, you could modify the ones you already have.

Of course, it’s worth noting that if you already have the hardware to do epoxy deposition and milling, you could probably just make new PCBs whenever you need them. However, PCB Renewal lets you save resources by not manufacturing new boards when you don’t have to.

We’ve seen work from [Huaishu Peng]’s research group before, too, in the form of an innovative “solderless PCB”.

Continue reading “PCB Renewal Aims To Make Old Boards Useful Again” →

Electric Catamaran Sails High Seas Of Inland Canada

May 4, 2025 by Bryan Cockfield 4 Comments

There are a number of plans for DIY boats available online, so [Phil] went in search of one for a custom catamaran to travel the inland waterways of Canada. But none of the plans he found had options for electric motors so he modified one popular plan to include not only that, but plenty of other unique features as well throughout a long series of videos.

This isn’t [Phil]’s first electric boat, either. His first was a monohull with a long canopy above, providing shade for the occupants and a platform to mount solar panels. But that one was top heavy and unstable, so he pivoted to this catamaran design instead which has the perk of not only stability but a small draft. The plans were modified to use a similar propulsion system, though, but mounting the heavy panels on the roof of this boat was much less problematic. The roof itself retracts, and also includes some mosquito netting to enclose the cabin. He’s also added a head which is situated inside one of the hulls and has doors which fit into the retractable roof structure as well.

For navigating the peaceful inland waterways of Canada like the famous Rideau Canal, the Trent Severn Waterway which [Phil] frequents, or even quiet Ontario lake towns like Bobcaygeon we can’t imagine a better way to go that a peaceful, small electric boat like this one.

As summer rolls around in the northern hemisphere we’ll hope to see other solar electric boats like these out on the water, like this smaller electric-assisted kayak or this much larger solar electric houseboat.

Continue reading “Electric Catamaran Sails High Seas Of Inland Canada” →

A Delay Line Memory Demo Board

May 4, 2025 by Lewin Day 10 Comments

Delay line memory is a technology from yesteryear, but it’s not been entirely forgotten. [P-Lab] has developed a demo board for delay-line memory, which shows how it worked in a very obvious way with lots of visual aids.

If you’re unfamiliar with the technology, it’s a form of memory that was used in classic computers like the Univac-I and the Olivetti Programma 101. It’s a sequential-access technology, where data is stored as pulses in some kind of medium, and read out in order. Different forms of the technology exist, such as using acoustic pulses in mercury or torsional waves passing through coiled nickel wire.

In this case, [P-Lab] built a solid state delay line using TTL ICs, capable of storing a full 64 bits of information and running at speeds of up to 150 kHz. It also features a write-queuing system to ensure bits are written at the exact correct time — the sequential-access nature of the technology means random writes and reads aren’t actually possible. The really cool thing is that [P-Lab] paired the memory with lots of LEDs to show how it works. There are lights to indicate the operation of the clock, and the read and write cycles, as well as individual LEDs indicating the status of each individual bit as they roll around the delay line. Combined with the hexadecimal readouts, it makes it easy to get to grips with this old-school way of doing things.

We’ve seen previous work from[P-Lab] in this regard using old-school core rope memory, too. Continue reading “A Delay Line Memory Demo Board” →

Frnisi DMC-100: A Clamp Meter Worth Cracking Open

May 4, 2025 by Heidi Ulrich 17 Comments

Not all clamp meters are the same, and this video shows just that. In a recent teardown by [Kerry Wong], the new Fnirsi DMC-100 proves that affordable doesn’t mean boring. This 10,000-count clamp meter strays from the classic rotary dial in favour of a fully button-based interface – a choice that’s got sparks flying in the comments. And yes, it even auto-resumes its last function after reboot, like it knows you’re busy frying other fish.

What sets this meter apart isn’t just its snappy interface or surprisingly nice gold-tipped probes. It’s the layered UX – a hackable interface where short- and long-presses unlock hidden menus, memory functions, and even a graphing mode. A proper “hold-my-beer” moment comes when you discover it can split-display voltage and current and calculate real-time power (albeit with a minor asterisk: apparent power only, no power factor). Despite a few quirks, like accidentally triggering the flashlight when squeezing the jaw, it holds up well in accuracy tests. Even at higher currents where budget meters usually wobble.

Continue reading “Frnisi DMC-100: A Clamp Meter Worth Cracking Open” →

A human hand is shown in the bottom right corner of the picture, holding one end of a pencil. A white, segmented, mechanical tentacle extends from the bottom left corner of the image and wraps around the other end of the pencil.

3D Printed Cable-Driven Mechanisms – Some Strings Attached

May 3, 2025 by Aaron Beckendorf 10 Comments

One of the most basic problems with robotic arms and similar systems is keeping the weight down, as more weight requires a more rigid frame and stronger actuators. Cable-driven systems are a classic solution, and a team of researchers from MIT and Zhejiang University recently shared some techniques for designing fully 3D printed cable-driven mechanisms.

The researchers developed a set of four primitive motion components: a bending component, a coil, screw-like, and a compressive component. These components can work together in series or parallel to make much more complicated structures. To demonstrate, the researchers designed a gripping tentacle, a bird’s claw, and a lizard-like walking robot, but much more complicated structures are certainly possible. Additionally, since the cable itself is printed, it can have extra features, such as a one-way ratcheting mechanism or bumps for haptic feedback.

These printed cables are the most novel aspect of the project, and required significant fine-tuning to work properly. To have an advantage over manually-assembled cable-driven systems, they needed to be print-in-place. This required special printer settings to avoid delamination between layers of the cable, cables sticking to other components, or cables getting stuck in the mechanism’s joints. After some experiments, the researchers found that nylon filament gives the best balance between cable strength and flexibility, while not adhering tightly to the PLA structure.

We’ve seen cable-driven systems here a few times before. If you’re interested in a deeper dive, we’ve covered that too.

Continue reading “3D Printed Cable-Driven Mechanisms – Some Strings Attached” →

Testing A Cheap Bench Power Supply Sold On Amazon

May 3, 2025 by Maya Posch 20 Comments

We’ve all seen those cheap bench power supply units (PSUs) for sale online, promising specifications that would cost at least a hundred dollars or more if it were a name brand model. Just how much of a compromise are these (usually rebranded) PSUs, and should you trust them with your electronics? Recently [Denki Otaku] purchased a cheap unit off Amazon Japan for a closer look, and found it to be rather lacking.

Internals of the cheap bench PSU reviewed by Denki Otaku on YouTube.

Major compromises include the lack of an output power switch, no way to check the set current limit without shorting the output, very slow drop in output voltage while adjusting due to the lack of a discharge circuit, and other usability concerns. That’s when the electrical performance of the PSU got tested.

Right off the bat a major issue in this cheap switching mode PSU is clear, as it has 200 mV peak-to-peak noise on its output, meaning very little output filtering. The maximum power output rating was also far too optimistic, with a large voltage drop observed. Despite this, it generally worked well, and the internals – with a big aluminium plate as heatsink – look pretty clean with an interesting architecture.

The general advice is to get a bench PSU that has features like an output power button and an easy way to set the voltage and current limits. Also do not connect it to anything that cares about noise and ripple unless you know that it produces clean, filtered output voltages.

Continue reading “Testing A Cheap Bench Power Supply Sold On Amazon” →