Audio On A Shoestring: DIY Your Own Studio-Grade Mic

January 14, 2025 by Heidi Ulrich 14 Comments

When it comes to DIY projects, nothing beats the thrill of crafting something that rivals expensive commercial products. In the microphone build video below, [Electronoobs] found himself inspired by DIY Perks earlier efforts. He took on the challenge of building a $20 high-quality microphone—a budget-friendly alternative to models priced at $500. The result: an engaging and educational journey that has it’s moments of triumph, it’s challenges, and of course, opportunities for improvement.

The core of the build lies in the JLI-2555 capsule, identical to those found in premium microphones. The process involves assembling a custom PCB for the amplifier, a selection of high-quality capacitors, and designing lightweight yet shielded wiring to minimize noise. [Electronoobs] also demonstrates the importance of a well-constructed metal mesh enclosure to eliminate interference, borrowing techniques like shaping mesh over a wooden template and insulating wires with ultra-thin enamel copper. While the final build does not quite reach the studio-quality level and looks of the referenced DIY Perks’ build, it is an impressive attempt to watch and learn from.

The project’s key challenge here would be achieving consistent audio quality. The microphone struggled with noise, low volume, and single-channel audio, until [Electronoobs] made smart modifications to the shielded wiring and amplification stages. Despite the hurdles, the build stands as an affordable alternative with significant potential for refinement in future iterations.

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Perfecting 20 Minute PCBs With Laser

January 5, 2025 by Al Williams 40 Comments

Normally, you have a choice with PCB prototypes: fast or cheap. [Stephen Hawes] has been trying fiber lasers to create PCBs. He’s learned a lot which he shares in the video below. Very good-looking singled-sided boards take just a few minutes. Fiber lasers are not cheap but they are within range for well-off hackers and certainly possible for a well-funded hackerspace.

One thing that’s important is to use FR1 phenolic substrate instead of the more common FR4. FR4 uses epoxy which will probably produce some toxic fumes under the laser.

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Break Me Off A Piece Of That Open Source Serial Adapter

December 25, 2024 by Tom Nardi 11 Comments

We know, you’ve already got a USB to serial adapter. Probably several of them, in fact. But that doesn’t mean you couldn’t use one more — especially when it’s as as cleverly designed as this one from [Anders Nielsen].

The first thing you notice about this adapter, and the big departure from the ones that are likely littering your parts bin, is that it terminates in a full-size male DSUB9 connector. With the ability to be directly plugged into a RS-232 port, this adapter will certainly catch the eye of retrocomputer enthusiasts. With a clever arrangement of jumpers, you can even reconfigure the RX and TX lines to be straight-through or cross over as needed.

But if you’re working with something that doesn’t have a literal serial port, no worries. All of the lines coming from the CH340G chip are broken out to a header so you can connect it up to whatever device you’re working with via jumpers.

In fact, if you’re really sure you’ll never need that RS232 feature, the PCB is even designed in such a way that you can simply snap it off. Admittedly it might seem a little odd to get a device like this if you didn’t want that capability. But once broken off, it’s not like the components go to waste. [Anders] has designed the board in such a way that if you flip it over and install a right-angle header, you can use the RS232 segment on a breadboard.

But the list of features doesn’t stop there. There’s also a 3.3 V regulator on board that you can use to power external circuits, as well as breakouts for the data lines in the USB-C connector. In keeping with the theme of the device, that part of the PCB can also be snapped off if you want to use it elsewhere.

Most folks probably’ won’t need all the capabilities offered by this particular serial adapter, and that’s fine. We’re still happy that it’s out in the wild and available for the community to use and adapt as an open source project.

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Rudolph’s Sleigh On A North Pole PCB

December 20, 2024 by Heidi Ulrich 18 Comments

Each Christmas, [Adam Anderson], [Daniel Quach], [Johan Wheeler], and [Gustav Abrahamsson] (going by ‘the Janky Jingle Crew’)—set themselves the challenge of outdoing their previous creations. Last year’s CH32 Fireplace brought an animated LED fire to life with CH32V003 microcontrollers.

This year, they’ve gone a step further with the North Pole Circuit, a holiday project that combines magnetic propulsion, festive decorations, and a bit of engineering flair. Inspired by a miniature speedway based on Friedrich Gauss’ findings, the North Pole Circuit includes sleighs and reindeer that glide along a custom PCB track, a glowing village with flickering lights, and a buzzer to play Christmas tunes.

The propulsion system works using the Lorentz force, where vertical magnets interact with PCB traces to produce motion. A two-phase design, similar to a stepper motor, ensures smooth operation, while guard rails maintain stability on curves. A separate CH32V003 handles lighting and synchronized jingles, creating a cohesive festive display. As we mentioned in the article on their last year’s creation, going from a one-off to a full batch will make one rethink the joy of repetitive production. Consider the recipients of these tiny Christmas cards quite the lucky ones. We deem this little gift a keeper to put on display when Christmas rolls around again.

This annual tradition highlights the Crew’s knack for combining fun and engineering. Curious about the details or feeling inspired to create your own? Explore the full details and files on their GitHub.

PCB Motor Holds Fast, Even After 1.6 Billion Spins

December 17, 2024 by Donald Papp 32 Comments

If you aren’t up to date with [Carl Bugeja]’s work with tiny brushless PCB motors, his summary video of his latest design and all the challenges it involved is an excellent overview.

Back in 2018 we saw [Carl]’s earliest versions making their first spins and it was clear he was onto something. Since then they have only improved, but improvement takes both effort and money. Not only does everything seemingly matter at such a small scale, but not every problem is even obvious in the first place. Luckily, [Carl] has both the determination and knowledge to refine things.

Hardware development is expensive, especially when less than a tenth of a millimeter separates a critical component from the junk pile.

The end result of all the work is evident in his most recent test bed: an array of twenty test motors all running continuously at a constant speed of about 37,000 RPM. After a month of this, [Carl] disassembled and inspected each unit. Each motor made over 53 million rotations per day, closing out the month at over 1.6 billion spins. Finding no sign of internal scratches or other damage, [Carl] is pretty happy with the results.

These motors are very capable but are also limited to low torque due to their design, so a big part of things is [Carl] exploring and testing different possible applications. A few fun ones include a wrist-mounted disc launcher modeled after a Spider-Man web shooter, the motive force for some kinetic art, a vibration motor, and more. [Carl] encourages anyone interested to test out application ideas of their own. Even powering a micro drone is on the table, but will require either pushing more current or more voltage, both of which [Carl] plans to explore next.

Getting any ideas? [Carl] offers the MotorCell for sale to help recover R&D costs but of course the design is also open source. The GitHub repository contains code and design details, so go ahead and make them yourself. Or better yet, integrate one directly into your next PCB.

Got an idea for an application that would fit a motor like this? Don’t keep it to yourself, share in the comments.

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Even Apple Get Their Parts Wrong Sometimes

November 27, 2024 by Jenny List 14 Comments

There can be few among those of us who produce printed circuit boards, who have not at some point placed a component the wrong way round, or with the wrong footprint. Usually this can be rectified with a bit of rework and a fresh board spin, but just occasionally these mishaps make it into the wild undetected. It seems nobody is immune, as [Doug Brown] is here to tell us with a tale of an Apple product with a misplaced capacitor.

The LC series of Macs came out through the early 1990s, and their pizza-box style cases could be found slowly turning yellow in universities and schools throughout that decade. Of them there was a persistent rumor of the LCIII had a misplaced capacitor, so when he received an unmodified original machine he took a look. The investigation is quite simple, but revealing — there are three power supply rails and one of the capacitors does have a significant leak.

The explanation is simple enough, the designer had placed a capacitor on each rail, with its negative side to the ground plane, but one of the rails delivers -5 volts. Thus the capacitor is the wrong way round, and must have failed pretty early in the lifetime of each LCIII. We’re curious then since so many of them went through their lives without the component being replaced, how the circuit remained functional. We’re guessing that there were enough other capacitors in the -5 volt line to provide enough smoothing.

Rapid Prototyping PCBs With The Circuit Graver

November 6, 2024 by Dave Rowntree 27 Comments

Walking around the alley at Hackaday Supercon 2024, we noticed an interesting project was getting quite a bit of attention, so we got nearer for a close-up. The ‘Circuit Graver’ by [Zach Fredin] is an unconventional PCB milling machine, utilizing many 3D printed parts, the familiar bed-slinger style Cartesian bot layout and a unique cutting head. The cutting tool, which started life as a tungsten carbide lathe tool, is held on a rotary (‘R’) axis but can also move vertically via a flexure-loaded carriage driven by a 13 kg servo motor.

The stocky flexure took a lot of iteration, as the build logs will show. Despite a wild goose chase attempting to measure the cutting force, a complete machine solution was found by simply making everything stiff enough to prevent the tool from chattering across the surface of the FR4 blank. Controlling and maintaining the rake angle was a critical parameter here. [Zach] actually took an additional step, which we likely wouldn’t have thought of, to have some copper blanks pre-fabricated to the required size and finished with an ENIG coating. It’s definitely a smart move!

To allow the production of PCB-class feature sizes compatible with a traditional PCB router, the cutting tool was sharpened to a much smaller point than would be used in a lathe using a stone. This reduced the point size sufficiently to allow feature sizes down to 4 mils, or at least that’s what initial characterization implied was viable. As you can see from the build logs, [Zach] has achieved a repeatable enough process to allow building a simple circuit using an SMT 74HC595 and some 0402 LEDs to create an SAO for this year’s Supercon badge. Neat stuff!

We see a fair few PCB mills, some 3D printed, and some not. Here’s a nice one that fits in that former category. Milling PCBs is quite a good solution for the rapid prototyping of electronics. Here’s a guide about that.

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