Software Defined Retro ROMs

July 19, 2025 by John Elliot V 6 Comments

Here’s something fun from our hacker [Piers]: Software Defined ROMs.

In this series of three videos, [Piers] runs us through what a software defined ROM is, how to make them, and then how to use them.

As [Piers] explains, one frustration a retro technician will face is a failed ROM chip. In the era he’s interested in, there are basically three relevant kinds of ROM chip, all 24-pin Dual Inline Package (DIP):

2364 ROM chip: 8KB; 1x chip-select line
2332 ROM chip: 4KB; 2x chip-select lines
2316 ROM chip: 2KB; 3x chip-select lines

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Screenshot of the cheatsheet being developed in Inkscape

Improve Your KiCad Productivity With These Considered Shortcut Keys

July 17, 2025 by John Elliot V 15 Comments

[Pat Deegan] from Psychogenic Technologies shows us two KiCad tips to save a million clicks, and he made a video to support it, embedded below.

In the same way that it makes sense for you to learn to touch type if you’re going to be using a computer a lot, it makes sense for you to put some thought and effort into your KiCad keyboard shortcuts keys, too.

In this video [Pat] introduces the keymap that he has come up with for the KiCad programs (schematic capture and PCB layout) and explains the rules of thumb that he used to generate his recommended shortcut keys, being:

one handed operation; you should try to make sure that you can operate the keyboard with one hand so your other hand can stay on your mouse
proximity follows frequency; if you use it a lot it should be close to hand
same purpose, same place; across programs similar functions should share the same key
birds of a feather flock together; similar and related functionality kept in proximate clusters
typing trounces topography; if you have to use both hands for typing you have to take your hand off the mouse anyway so then it doesn’t really matter where on the keyboard the shortcut key is

You can find importable KiCad keymaps and customizable SVG cheatsheets in the downloads section.

[Pat]’s video includes some other tips and commentary, but for us the big takeaway was the keymaps. He’s also got a course that you can follow along with for free. And if you haven’t been keeping abreast of developments, KiCad is now at version 9, as of February this year.

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Does Made-in-America Make Sense For PCB Prototyping?

July 6, 2025 by Tyler August 96 Comments

These are tough times for American hackers, and rife with uncertainty. Trade wars are on, off, on again– who can keep track? If you’re used to getting everything from China, that can really cramp your style. [Jeremy Cook] took the time to write up his experience prototyping with American-made PCBs, just in time for us to totally miss Independence Day.

The project was a simple nightlight, using a single LED, a photoresistor, a transistor, and a CR2032 battery. The CR2032 battery does complicate things, though: [Jeremy] figured out a neat way to hold the battery using a PCB cutout, but it needs to be a 0.8 mm board. (That’s going to matter in a moment.) He’s put that PCB on GitHub if you’re interested.

To start off, JLBPCB is the Chinese clearing house of choice for [Jeremy], and they quoted a very cheap $7.10 for 20 boards. The problem was that shipping across the Pacific Ocean, plus the ever-wavering tariff charge, brought the price to $48.08. About five dollars of which was from tariffs; the rest you can put down to the cost of jet fuel and the size of the Pacific Ocean.

On the other hand, OSH Park, was able to get [Jeremy] three of their pretty purple PCBs for $7.75 all-inclusive. Overall, since he’s prototyping and does not want 20 boards this revision, [Jeremy] saves quite a lot by staying local– including the environmental impact of shipping and laxer regulations in China, if that sort of thing matters to you.

The suprizing thing is the turnaround time: [Jeremy] got his pretty purple PCBs from OSH Park a full twenty days after ordering. Similar orders from China take only a week, which is just mind-blowing when you stop and think about the great honking ocean in the way. We could perhaps cut OSH Park some slack in that 0.8 mm boards are not the most common, but their quoted turnaround time for two-layer prototypes is minimum 12 days.

They do offer a “super-swift” option for two-layer boards, but then they lose on price. As [Jeremy] points out, there are always tradeoffs. If you’re really in a hurry, nothing’s faster than milling the boards yourself. Or you could go the old-school toner-transfer etching route.

Our thanks to [Jeremy] for the tip. If you’ve got a better way to prototype, do send us a tip about it. Also, please us know in the comments if you’ve tried an in-country PCB fabricator, and how it compared to the usual offerings from the PRC.

Using an SMD capacitor as a clip for flash media on a circuit board.

SMD Capacitor Doubles As Cheap SD Card Latch

July 4, 2025 by John Elliot V 41 Comments

Here’s a clever hack. Simple, elegant, and eminently cost-effective: using an SMD capacitor to hold your flash media in place!

This is a hack that can pretty much be summed up with just the image at the top of the page — a carefully placed SMD capacitor soldered to a routed tab makes for an extremely cost effective locking mechanism for the nearby SD card slot. There’s just enough flexibility to easily move the capacitor when its time to insert or eject your media.

It’s worth noting that the capacitor in this example doesn’t even appear to be electrically connected to anything. But there’s also no reason you couldn’t position one of the capacitors in your existing bill of materials (BOM). This form of mechanical support will be much cheaper than special purpose clips or mounts. Not a big deal for low-volume projects, but if you’re going high-volume this is definitely something to keep in mind.

If you’re just getting started with SMD capacitors then one of the first things to learn is how to solder them. Also, if you’re hoping to salvage them then try to look for newer equipment which is more likely to have SMD components than through-hole. If you’re planning to use your capacitors for… “capacitance” (how quaint), you can start by learning the basics. And if you want to know everything you can learn about the history of capacitors, too.

Thanks to [JohnU] for writing in to let us know about this one. Have your own natty hacks? Let us know on the tipsline!

Kludge Compensates For Kaput Component With Contemporary Capacitor

June 16, 2025 by Seth Mabbott 14 Comments

It is a well-known reality of rescuing certain older electronic devices that, at some point, you’re likely going to have to replace a busted capacitor. This is the stage [Kevin] is at in the 3rd installment in his saga of reviving a 50-year-old Military Tektronix oscilloscope.

[Kevin] recently discovered a failed capacitor in the power supply for this vintage analog scope. Having identified and removed the culprit, it was time to find a way to replace the faulty component with a modern equivalent. The original capacitor is out of fashion to the degree that a perfect replacement would be impractical and likely not desirable. This job would call for a bit of adaptation.

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Adapting An Old Rotary Dial For Digital Applications

June 13, 2025 by John Elliot V 27 Comments

Today in old school nostalgia our tipster [Clint Jay] wrote in to let us know about this rotary dial.

If you’re a young whippersnapper you might never have seen a rotary dial. These things were commonly used on telephones back in the day, and they were notoriously slow to use. The way they work is that they generate a number of pulses corresponding to the number you want to dial in. One pulse for 1, two pulses for 2, and so on, up to nine pulses for 9, then ten pulses for 0.

We see circuits like this here at Hackaday from time to time. In fact, commonly we see them implemented as USB keyboards, such as in Rotary Dial Becomes USB Keyboard and Rotary Dialer Becomes Numeric Keypad.

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Solder Stencil Done Three Ways

June 6, 2025 by Matt Varian 29 Comments

This project, sent in by [Henk], goes through a few different ways to make a solder stencil using a vinyl cutter, a CO2 laser, and a fiber laser.

The project starts with identifying a method to convert the board’s Gerber files to a PNG, which is ultimately used to create a vector file for use with the laser. The first stencil, made with the CO2 laser, was cut out of masking tape. This worked fine for larger cutouts and is certainly a cheap option if you don’t have too many small components. A slightly better approach with the CO2 laser was using vinyl sheet release paper, which seemed to hold together better than the tape.

Laser-cut masking tape works, but not for long.

A vinyl cutter was also used as an experiment, but it didn’t perform as well as the CO2 laser, as expected, since the cutter uses a knife rather than light, leading to some tearing issues.

The final method utilized a fiber laser and an empty drink can to create a metal stencil. First, the can had to be cut open, heated, and flattened. The fiber laser was able to cut clean footprints in the aluminum, creating a stencil that would hold up to more use than the paper variations.

The finale of this exploration into laser stencil making was using the fiber laser to solder the board together. The stencil was used to spread paste on the pads, parts were placed on the board, and then the fiber laser heated the solder paste to solder them to the board. The board looked a bit toasty afterwards, but we imagine the process could be fine-tuned to reduce the collateral damage a bit.

Once you’ve got your stencil ready to go, you can combine it with a 3D printed jig to hold the PCB while you apply the solder paste.