Building An Analog Echo Plate

June 5, 2025 by Lewin Day 7 Comments

These days, when you think reverb, you probably think about a guitar pedal or a plugin in your audio software. But you can also create reverb with a big metal plate and the right supporting electronics. [Tully] from [The Tul Studio] shows us how.

Basically, if you’ve ever smacked a big sheet of metal and heard the thunderous, rippling sound it makes, you already understand the concept here. To turn it into a studio effect, you use transducers to deliver the sound into the plate of metal, and then microphones to pick it back up again at some other point on the plate. Since the sound takes time to travel through the plate, you get a reverb effect.

[The Tul Studio] used a huge cold-rolled steel plate, standing one meter wide and two meters tall. The plate itself is hung from picture chain, which is strong enough to carry its weight. Old car tweeters are repurposed to act as pickups, while a larger speaker is used to drive sound into the plate. “The key to making it sound not like a tin can is the actual EQ and the electronics,” [Tully] explains, providing resources for this purposes.

We love lots of lovely reverbing things around these parts; oddball delays, too! Video after the break.

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Passive Saturation Box Is A Cheap Way To Distort Your Sound

June 4, 2025 by Lewin Day 10 Comments

Distortion pedals and overdrive effects usually have a bunch of lovely transistors or op-amps inside and lots of knobs and dials to tweak the sound to your personal taste. However, it’s possible to get some crunchiness in your audio signal without all that fuss, as [Simon Hutchinson] demonstrates with his $2 “analog saturation box”.

The effect is achieved quite simply by installing a pair of diodes in opposite orientations, connected from the signal path to ground. This configuration is also known as wiring diodes in “anti-parallel.” When the signal increases in amplitude beyond the diode’s forward voltage, the diode conducts and the signal’s peak is clipped off, which creates a distorted tone. Since there are two diodes, one in each orientation, both the tops and bottoms of the AC audio signal are clipped in this manner.

The amount of clipping is highly dependent on the diodes chosen and the strength of the signal you’re working with. Silicon diodes clip around 0.7 V, while germanium diodes clip at about 0.3 V, but that doesn’t give you much flexibility. You can work with this to some degree, though. You can up the minimum clipping level by stacking more diodes in series in each direction, or you can put in a potentiometer to vary your signal’s level before it hits the diodes. Really, though, this hard voltage limit is why more commonly, we use active distortion or overdrive effects that have more options for gain and level and such.

[Simon Hutchinson] does an able job of explaining the effect and demonstrates its use with some simple beats. As a passive device, it’s pretty one note—there’s no EQs to mess with the frequency response, and no ability to change anything else about the sound, either. Still, it’s interesting to hear the effect it does have on a signal, and you might just find this is all the distortion you need. If you’d rather go into full-fat distortion though, we’ve covered that too.

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NES Zapper Becomes Telephone

May 25, 2025 by Bryan Cockfield 9 Comments

Although there was a time in the 80s (and early 90s for fans of the SuperScope) where light guns were immensely popular, with games like DuckHunt cultural touchstones, their time in the video game world has largely come to an end. We might occasionally pick up a Zapper for the NES and play this classic out of nostalgia, but plenty of people are looking for other things that these unique video game controllers can do instead. [Nick] has turned one of his old NES peripherals into a wireless phone.

The way the original Zapper worked was by looking for a certain pattern of pixels that displayed for a fraction of a second whenever the trigger was pulled. Bypassing the anti-cheat mechanism that looks only for qualities of light coming from CRT screens of the day effectively turns the light gun into an analog light sensor which is used for receiving the audio from the phone’s base station via a laser. Of course there were no microphones present within the original hardware so one is added, wiring its output to another laser that communicates to the base station. With the light gun pointed directly at this base station, audio is communicated back and forth by varying the strengths of these small lasers and listening to them on the other end with photodiodes.

[Nick] does point out that this isn’t a great phone, largely because it needs to be pointed exactly at the right spot to work at all, although we do agree that it’s an interesting project that demonstrates what the original hardware could do with a few of its limitations removed. There are a few other ways of bringing these devices into the modern world, with one of our favorites being this laser pointer with additional hardware from a Wiimote that could also function as a mouse.

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Who Needs 100K Speakers When You’ve Got A 3D Printer?

May 24, 2025 by Tyler August 65 Comments

The B&W Nautilus is, depending who you ask, either infamous or an icon of modern design. Want the look but don’t have a hundred grand to spare? [Every Project All at Once] has got a Nautilus-inspired design on printables you can run off for pennies. He also provides a tutorial video (embedded below) so you can follow along with his design process and get build instructions.

The model was done in Blender, and is designed to contain a 3.5″ full-range driver by Dayton Audio — a considerable simplification from the array of woofers and tweeters in the original Nautilus. On the other hand, they cost considerably less than a car and have no production wait list. [Every Project All At Once] is apparently working on a matching woofer if that interests you, but unless he invests in a bigger printer it seems we can safely say that would require more assembly than this project.

Of course it would also be possible to copy B&W’s design directly, rather than print a loose inspiration of it as makers such as [Every Project All At Once] have done, but what’s the fun in that? It’s a much more interesting hack to take an idea and make it your own, as was done here, and then you can share the design without worrying about a luxury brand’s legal team.

Desktop 3D printing offers a wealth of possibilities for would-be speaker makers, including the possibility of rolling your own drivers.

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Round Displays Make Neat VU Meters

May 5, 2025 by Lewin Day 11 Comments

You can still get moving-needle meters off the shelf if you desire that old school look in one of you projects. However, if you want a more flexible and modern solution, you could use round displays to simulate the same thing, as [mircemk] demonstrates.

At the heart of the build is an ESP32 microcontroller, chosen for its fast clock rate and overall performance. This is key when drawing graphics to a display, as it allows for fast updates and smooth movement — something that can be difficult to achieve on lesser silicon. [mircemk] has the ESP32 reading an audio input and driving a pair of GC9A01 round displays, which are the perfect form factor for aping the looks of a classic round VU meter. The project write-up goes into detail on the code required to simulate the behavior of a real meter, from drawing the graphics to emulating realistic needle movements, including variable sweep rates and damping.

The cool thing about using a screen like this is the flexibility. You can change the dials to a different look — or to an entirely different kind of readout — at will. We’ve seen some of [mircemk]’s projects before, too, like this capable seismometer. Video after the break.

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All-Band Radio Records Signals, Plays MP3s

May 4, 2025 by Tyler August 9 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.

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Crossing Commodore Signal Cables On Purpose

April 29, 2025 by Bryan Cockfield 19 Comments

On a Commodore 64, the computer is normally connected to a monitor with one composite video cable and to an audio device with a second, identical (although uniquely colored) cable. The signals passed through these cables are analog, each generated by a dedicated chip on the computer. Many C64 users may have accidentally swapped these cables when first setting up their machines, but [Matthias] wondered if this could be done purposefully — generating video with the audio hardware and vice versa.

Getting an audio signal from the video hardware on the Commodore is simple enough. The chips here operate at well over the needed frequency for even the best audio equipment, so it’s a relatively straightforward matter of generating an appropriate output wave. The audio hardware, on the other hand, is much less performative by comparison. The only component here capable of generating a fast enough signal to be understood by display hardware of the time is actually the volume register, although due to a filter on the chip the output is always going to be a bit blurred. But this setup is good enough to generate large text and some other features as well.

There are a few other constraints here as well, namely that loading the demos that [Matthias] has written takes so long that the audio can’t be paused while this happens and has to be bit-banged the entire time. It’s an in-depth project that shows mastery of the retro hardware, and for some other C64 demos take a look at this one which is written in just 256 bytes.

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