Building The Simplest Atomic Force Microscope

March 23, 2025 by Elliot Williams 22 Comments

Doing it yourself may not get you the most precise lab equipment in the world, but it gets you a hands-on appreciation of the techniques that just can’t be beat. Today’s example of this adage: [Stoppi] built an atomic force microscope out of mostly junk parts and got pretty good results, considering. (Original is in German; read it translated here.)

The traditional AFM setup uses a piezo micromotor to raise and lower the sample into a very, very fine point. When this point deflects, it reads the height from the piezo setup and a motor stage moves on to the next point. Resolution is essentially limited by how fine a point you can make and how precisely you can read from the motion stages. Here, [stoppi]’s motion stage follows the traditional hacker avenue of twin DVD sleds, but instead of a piezo motor, he bounces a laser off of a mirror on top of the point and reads the deflection with a line sensor. It’s a clever and much simpler solution.

A lot of the learnings here are in the machine build. Custom nichrome and tungsten tips are abandoned in favor of a presumably steel compass tip. The first-draft spring ended up wobbling in the X and Y directions, rather than just moving in the desired Z, so that mechanism got reinforced with aluminum blocks. And finally, the line sensors were easily swamped by the laser’s brightness, so neutral density filters were added to the project.

The result? A nice side effect of the laser-bouncing-off-of-mirror setup is that the minimum resolvable height can be increased simply by moving the line sensors further and further away from the sample, multiplying the deflection by the baseline. Across his kitchen, [stoppi] is easily able to resolve the 35-um height of a PCB’s copper pour. Not bad for junk bin parts, a point from a crafts store, and a line sensor.

If you want to know how far you can push a home ~~AFM~~ microscope project, check out [Dan Berard]’s absolutely classic hack. And once you have microscope images of every individual atom in the house, you’ll, of course, want to print them out.

Card Radios Remembered

March 22, 2025 by Al Williams 17 Comments

We know how [Techmoan] feels. In the 1980s we had a bewildering array of oddball gadgets and exciting new tech. But as kids we didn’t have money to buy a lot of what we saw. But he had a £5 note burning a hole in his pocket from Christmas and found a Casio RD-10 “card radio” on sale and grabbed it. He’s long-ago lost that one, but he was able to find a new old stock one and shows us the little gadget in the video below.

The card-thin (1.9 mm) FM radio had many odd features, especially for the 1980s. For one thing, it took a coin cell, which was exotic in those days. The headphones had a special flat connector that reminded us of an automotive fuse. Even the idea of an earbud was odd at that time.

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Building A Handheld Pong Game

March 21, 2025 by Lewin Day 3 Comments

Pong was one of the first video games to really enter the public consciousness. While it hasn’t had the staying power of franchises like Zelda or Call of Duty, it nonetheless still resonates with gamers today. That includes [Arnov Sharma], who put together this neat handheld version using modern components.

An ESP32 development board serves as the brains of the operation. Capable of operating at many hundreds of megahertz, it has an excessive amount of power for an application as simple as this. Nonetheless, it’s cheap, and it gets the job done. It’s paired with an SSD1306 OLED screen of 124 x 32 resolution. That might not sound like much, but it’s plenty when you’re just drawing two paddles and a ball bouncing between them. Control is via a pair of SMD push buttons for a nice responsive feel.

What’s really neat, though, is the presentation. [Arnov] wrapped the electronics in a neat bean-shaped housing that vaguely apes game controllers of the 16-bit era. Indeed, [Arnov] explains that it was inspired by the Sega Genesis specifically. It looks great with the black PCBs integrated so nicely with the bright orange 3D printed components, and looks quite comfortable to use, too.

It might be a simple project, but it’s done rather well. Just by thinking about color choices and how to assemble the base components, [Arnov] was able to create an attractive and functional game that’s a lot more eye catching than some random boards thrown in an old project box. Indeed, we’ve featured stories on advanced FR4/PCB construction techniques before, too. Meanwhile, if you’re creating your own projects with similar techniques, don’t hesitate to let us know!

Reviving A Maplin 4600 DIY Synthesizer From The 1970s

March 19, 2025 by Donald Papp 16 Comments

A piece of musical history is the Maplin 4600, a DIY electronic music synthesizer from the 1970s. The design was published in an Australian electronics magazine and sold as a DIY kit, and [LOOK MUM NO COMPUTER] got his hands on an original Maplin 4600 that he refurbishes and puts through its paces.

Inserting conductive pegs is how the operator connects different inputs and outputs.

The Maplin 4600 is a (mostly) analog device with a slightly intimidating-looking layout. It features multiple oscillators, mixers, envelope generators, filters, and a complex-looking patch bay on the right hand side that is reminiscent of a breadboard. By inserting conductive pins, one can make connections between various inputs and outputs.

Internally the different features and circuits are mostly unconnected from one another by default, so the patch board is how the instrument is “programmed” and the connections made can be quite complex. The 4600 is one of a few synthesizer designs by [Trevor Marshall], who has some additional details about on his website.

The video (embedded below) is a complete walk-through of the unit, including its history, quirks, and design features. If you’d like to skip directly to a hands-on demonstrating how it works, that begins around the 10:15 mark.

Synthesizers have a rich DIY history and it’s fascinating to see an in-depth look at this one. And hey, if you like your synths complex and intimidating, do yourself a favor and check out the Starship One.

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Probably The Simplest Sequencing Synth

March 15, 2025 by Jenny List 31 Comments

With inexpensive microntrollers capable of the most impressive feats of sound synthesis, it’s not so often we see projects that return to an earlier style of electronic music project. The 1-bit synth from [Electroagenda] takes us firmly into that territory, employing that most trusty of circuits, a 555.

It’s a time-honored circuit, a 555 provides a note clock that drives a 4017 that functions as a sequencer. This switches in a set of voltage dividers, which in turn control another 555 oscillator that produces the notes. It’s a fun toy straight from the 1970s, right down to the protoboard and hookup wire construction. There’s a demo video with some lovely beeps below, and we think most of you should have what it takes to make your own.

If you’re seeking more inspiration, may we introduce you to our Logic Noise series?

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Newspaper clipping with words 'speaking personally' and a photo

A Fast Rewind To The Era Of Tapesponding

March 12, 2025 by Heidi Ulrich 5 Comments

Imagine a time before Discord servers and cheap long-distance calls. Back in the 1950s, a curious and crafty group of enthusiasts invented their own global social network: on reels of magnetic tape. They called it tapesponding (short for tape corresponding), and it was a booming hobby for thousands of radio hams, tinkerers, and audio geeks. Here’s the original video on this analog marvel.

These folks weren’t just swapping mixtapes. They crafted personal audio letters, beamed across the globe on 3-inch reels. DIY clubs emerged everywhere: World Tape Pals (Texas-based, naturally) clocked 5,000 members from “every Free Nation” – which frames it in a world in terms of East vs. West. Some groups even pooled funds to buy shared tape decks in poorer regions – pure hacker spirit. The tech behind it: Speeds of 3¾ IPS, half-track mono, round-robin reels, and rigorous trust networks to avoid ghosters. Honestly, it makes IRC net ops look soft. Tapesponding wasn’t just for chatty types. It fostered deep friendships, even marriages. It was social engineering before that term was coined. The video is below the break.

What are your thoughts on this nostalgic way of long-distance communication? The warm whirring of a spinning tape reel? The waiting time before your echo is returned? Or are have you skipped all the analog mechanics and shouted out into the LoRaWAN void long ago?

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EPROM-based Enigma Machine

March 12, 2025 by Bryan Cockfield 5 Comments

The Enigma machine is perhaps one of the most legendary devices to come out of World War II. The Germans used the ingenious cryptographic device to hide their communications from the Allies, who in turn spent an incredible amount of time and energy in finding a way to break it. While the original Enigma was a complicated electromechanical contraption, [DrMattRegan] recently set out to show how its operation can be replicated with an EPROM.

The German Enigma machine was, for the time, an extremely robust way of coding messages. Earlier versions proved somewhat easy to crack, but subsequent machines added more and more complexity rendering them almost impenetrable. The basis of the system was a set of rotors which encrypted each typed letter to a different one based on the settings and then advanced one place in their rotation, ensuring each letter was encrypted differently than the last. Essentially this is a finite-state machine, something perfectly suited for an EPROM. With all of the possible combinations programmed in advance, an initial rotor setting can be inputted, and then each key press is sent through the Enigma emulator which encrypts the letter, virtually advances the rotors, and then moves to the next letter with each clock cycle.

[DrMattRegan]’s video, also linked below, goes into much more historical and technical detail on how these machines worked, as well as some background on the British bombe, an electromechanical device used for decoding encrypted German messages. The first programmable, electronic, digital computer called Colossus was also developed to break encrypted Enigma messages as well, demonstrating yet another technology that came to the forefront during WWII.

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