Apollo-era PCB Reverse Engineering To KiCad

November 25, 2024 by Chris Lott 24 Comments

Earlier this year [Skyhawkson] got ahold of an Apollo-era printed circuit board which he believes was used in a NASA test stand. He took high quality photos of both sides of the board and superimposed them atop each other. After digging into a few obsolete parts from the 1960s, he was able to trace out the connections. I ran across the project just after making schematics for the Supercon badge and petal matrix. Being on a roll, I decided to take [Skyhawkson]’s work as a starting point and create KiCad schematics. Hopefully we can figure out what this circuit board does along the way.

The board is pretty simple:

approximately 6.5 x 4.5 inches
22 circuit edge connector 0.156 in pitch
31 ea two-terminal parts ( resistors, diodes )
3 ea trimmer potentiometers
7 ea transistors
parts arranged in 4 columns

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Watch SLS 3D Printed Parts Become Printed Circuits

June 20, 2024 by Donald Papp 38 Comments

[Ben Krasnow] of the Applied Science channel recently released a video demonstrating his process for getting copper-plated traces reliably embedded into sintered nylon powder (SLS) 3D printed parts, and shows off a variety of small test boards with traces for functional circuits embedded directly into them.

Here’s how it works: The SLS 3D printer uses a laser to fuse powdered nylon together layer by layer to make a plastic part. But to the nylon powder, [Ben] has added a small amount of a specific catalyst (copper chromite), so that prints contains this catalyst. Copper chromite is pretty much inert until it gets hit by a laser, but not the same kind of laser that sinters the nylon powder. That means after the object is 3D printed, the object is mostly nylon with a small amount of (inert) copper chromite mixed in. That sets the stage for what comes next.

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Nearly-Destroyed Commodore Gets New Life

April 26, 2024 by Bryan Cockfield 10 Comments

We all have our shiny, modern computers for interacting with the modern world, but at times they can seem a little monochromatic. Even the differences between something like macOS and Windows for the average user often boil down to which operating system loads an Internet browser. There are obviously more differences than that, but back in the 80s it was much more extreme with interoperability a pipe dream in most cases. What keeps drawing people to maintaining and using computers from that chaotic era is more tangible compared to modern machines, and that is meant quite literally; computers from this era can be saved from an extreme amount of degradation like this Commodore that was nearly completely destroyed before it was re-discovered.

The first step was to restore the case of this Commodore PC20-III, but the restoration of the computer’s internals took a bit more time. First, the entire board was de-soldered, with any rare chips being set aside for future use. Unfortunately the board itself was too corroded and otherwise damaged to be used, but since these were just two-layer boards it could be photographed and then re-created in CAD software to make a near-perfect duplicate of the original. The team at [The Cave] took the opportunity to add patch wires which would have been present in the original machine into the PCB, and made some other upgrades as well like adding sockets to various chips that would have been originally soldered to the board.

The passive components, especially capacitors, were brand new as well and some period-correct components such as a monitor and keyboard finish out the build. The computer boots on the first try, and is quickly put through its paces testing the hard disk drive, using the old floppy drive, and even playing a few video games from the era. The fact that retrocomputers like these are easy (by modern standards) to reverse engineer and restore surely leads to their continued popularity, and we’ve seen everything from C64s to this 128DCR get a similar full restoration.

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DIY Laser For Ablating Metal

July 17, 2023 by Bryan Cockfield 51 Comments

For those who wish to go beyond through-hole construction on perfboard for their circuit boards, a printed circuit board is usually the next step up. Allowing for things like surface-mount components, multi-layer boards, and a wider array of parts, they are much more versatile but do have a slight downside in that they are a little bit harder to make. There are lots of methods for producing them at home or makerspace, though, and although we’ve seen plenty of methods for their production like toner transfer, photoresist, and CNC milling, it’s also possible to make them using laser ablation, although you do need a special laser to get this job done.

The problem with cutting copper is that it reflects infra-red, so a higher-wavelength ~~blue~~ green laser is used instead. And because you want to ablate the copper, but not melt the surrounding areas or cut straight through the board, extremely short, high-power pulses are the way to go. Here, the [Munich Fab Lab] is using 9 kW pulses of around 30 microseconds each. With these specifications the copper is ablated from the surface of the board allowing for fine details in the range of about 20 µm, which is fine enough for just about any circuit board. The design of the laser head itself is worth a look.

Aside from the laser, the rest is standard CNC machine fodder, but with an emphasis on safety that’s appropriate for a tool in a shared workspace, and the whole project is published under an open license and offers an affordable solution for larger-scale PCB production with extremely fine resolution and without the need for any amounts of chemicals for the more common PCB production methods. There is a lot more information available on the project’s webpage and its GitHub page as well.

Of course, there are other methods of producing PCBs by laser if you happen to have a 20 W fiber laser just kicking around.

Laser-Cut Solder Masks From Business Cards

April 9, 2021 by Bryan Cockfield 22 Comments

There are plenty of ways to make printed circuit boards at home but for some features it’s still best to go to a board shop. Those features continue to decrease in number, but not a lot of people can build things such as a four-layer board at home. Adding a solder mask might be one of those features for some, but if you happen to have a laser cutter and a few business cards sitting around then this process is within reach of the home builder too.

[Jeremy Cook] is lucky enough to have a laser cutter around, and he had an idea to use it to help improve his surface mount soldering process. By cutting the solder mask layer into a business card with the laser cutter, it can be held on top of a PCB and then used as a stencil to add the solder paste more easily than could otherwise be done. It dramatically decreases the amount of time spent on this part of the process, especially when multiple boards are involved since the stencil can be used multiple times.

While a laser cutter certainly isn’t a strict requirement, it certainly does help over something like an X-acto knife. [Jeremy] also notes that this process is sometimes done with transparency film or even Kapton, which we have seen a few times before as well.

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Journey Through The Inner Workings Of A PCB

December 10, 2019 by Kerry Scharfglass 20 Comments

Most electronics we deal with day to day are comprised of circuit boards. No surprise there, right? But how do they work? This might seem like a simple question but we’ve all been in the place where those weird green or black sheets are little slices of magic. [Teddy Tablante] at Branch Eduction put together a lovingly crafted ~~walkthrough~~ flythrough video of how PCB(A)s work that’s definitely worth your time.

[Teddy]’s video focuses on unraveling the mysteries of the PCBA by peeling back the layers of a smartphone. Starting from the full assembly he separates components from circuit board and descends from there, highlighting the manufacturing methods and purpose behind what you see.

What really stands out here is the animation; at each step [Teddy] has modeled the relevant components and rendered them on the PCBA in 3D. Instead of relying solely on hard to understand blurry X-ray images and 2D scans of PCBAs he illustrates their relationships in space, an especially important element in understanding what’s going on underneath the solder mask. Even if you think you know it all we bet there’s a pearl of knowledge to discover; this writer learned that VIA is an acronym!

If you don’t like clicking links you can find the video embedded after the break. Credit to friend of the Hackaday [Mike Harrison] for acting as the best recommendation algorithm and finding this gem.

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Bandpass Filters From The CNC Mill

July 14, 2018 by Brian McEvoy 30 Comments

A bandpass allows a certain electrical signal to pass while filtering out undesirable frequencies. In a speaker bandpass, the mid-range speaker doesn’t receive tones meant for the tweeter or woofer. Most of the time, this filtering is done with capacitors to remove low frequencies and inductors to remove high frequencies. In radio, the same concept applies except the frequencies are usually much higher. [The Thought Emporium] is concerned with signals above 300MHz and in this range, a unique type of filter becomes an option. The microstrip filter ignores the typical installation of passive components and uses the copper planes of an unetched circuit board as the elements.

A nice analogy is drawn in the video, which can also be seen after the break, where the copper shapes are compared to the music tuning forks they resemble. The elegance of these filters is their simplicity, repeatability, and reproducability. In the video, they are formed on a CNC mill but any reliable PCB manufacturing process should yield beautiful results. At the size these are made, it would be possible to fit these filters on a business card or a conference badge.

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