Building A Solar-Powered, Supercapacitor-Based Speaker

December 15, 2023 by 12 Comments

Inspired by many months of hours-long load shedding in South Africa, [JGJMatt] decided to make a portable speaker that can play tunes for hours on a single charge and even charge off the integrated solar panel to top the charge off. None of this should sound too surprising, but what differentiates this speaker is the use of two beefy 400 F, 2.7 V supercapacitors in series rather than a lithium-ion battery on the custom PCB with the Ti TPA2013D1 Class-D mono amplifier.

Insides of the speaker prior to stuffing and closing.
Insides of the speaker prior to stuffing and closing.

The reason for supercapacitors is two-fold. The first is that their lifespan is much longer than that of Li-ion batteries, the second that they can charge much faster. The disadvantages of supercapacitors come in the form of their lower energy density and linear discharge voltage. For the latter issue the TPA2301D1 amplifier has a built-in boost converter for an input range from 1.8 – 5.5 V, and despite the lower energy density a solid 6 hours of playback are claimed.

Beyond the exquisitely finished 3D printed PETG shell and TPU-based passive bass radiator, the functionality consists out of a single full-range speaker and an analog audio input (TRS jack and USB-C). To add Bluetooth support [JGJMatt] created a module consisting out of a Bluetooth module that connects to the USB-C port for both power and analog audio input.

Charging the speaker can be done via the USB-C port, as well as via the solar panel. This means that you can plug its USB-C port into e.g. a laptop’s USB-C port and (hopefully) charge it and play back music at the same time.

For those feeling like replicating this feat, the Gerbers, bill of materials, enclosure STLs, and everything else needed can be be found in the tutorial.

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It’s Time You Built A Smart Pocket Watch

September 13, 2023 by 39 Comments

There’s just something about a pocket watch that screams class compared to the barbaric act of bending your arm, or the no-fun way of looking at your phone.

But smartwatches are dumb, analog things that mostly look pretty. Or are they? [JGJMatt] proves otherwise with their stunning DIY smart pocket watch. It is essentially a cheap smart watch from Amazon stuffed into the shell of an old pocket watch, but you know it’s not quite that simple.

On the easier side of things, [JGJMatt] had to come up with a 3D-printed bracket to hold the smart watch’s guts. On the harder end of the spectrum, he ended up building the charging port into the crown, where the latch used to be.

This is a beautiful build for sure, and a great way to reuse something that might otherwise end up thrown away or melted down.

Looking for a cool alternative pocket watch that’s a little easier to build? Check out [JGJMatt]’s pocket sundial.

Old Film Camera Modified For Different Chemistry

August 3, 2023 by 12 Comments

While most photographers have moved on to digital cameras with their numerous benefits, there are a few artists out there still taking pictures with film. While film is among the more well-known analog photographic methods available, there are chemically simpler ways of taking pictures available for those willing to experiment a little bit. Cyanotype photography is one of these methods, and as [JGJMatt] shows, it only takes a few commonly available chemicals, some paper, and a slightly modified box camera to get started.

Cyanotype photography works by adding UV-reactive chemicals to paper and exposing the paper similarly to how film would be exposed. The photographs come out blue wherever the paper wasn’t exposed and white where it was. Before mixing up chemicals and taking photos, though, [JGJMatt] needed to restore an old Kodak Brownie camera, designed to use a now expensive type of film. Once the camera is cleaned up, only a few modifications are needed to adapt it to the cyanotype method, one of which involves placing a magnet on the shutter to keep it open for the longer exposure times needed for this type of photography. There is some development to do on these pictures, but it’s relatively simple to do in comparison to more traditional chemical film development.

For anyone looking for a different way of taking photographs, or even those looking for a method of taking analog pictures without the hassle of developing film or creating a darkroom, cyanotype offers a much easier entry point and plenty of artists creating images with this method don’t use a camera at all. There are plenty of other photographic chemistries to explore as well; one of our favorites uses platinum to create striking black-and-white photos.

Planar Speaker Build Uses Hard Drive Magnets

July 15, 2023 by 3 Comments

We like to see people building things that are a little unusual, and we really like it when said unusual thing uses salvaged parts. This project from [JGJMatt] ticks all our boxes — the build creates a planar speaker that uses salvaged magnets from a hard drive.

A planar speaker, according to the post, uses wires and magnets to manipulate a flat film that acts as the transducer. The speaker housing is 3D printed and looks great but is otherwise unremarkable. The fun starts when a Dremel with a diamond disk cuts the magnets in half. Cutting neodymium poses several challenges. For example, if you heat the material up too much while cutting, it can lose its magnetism.

With the proper magnets, you can move to the tedious method of creating the coils. The post shows three different methods. But the part we really liked was using a resin 3D printer as a UV source to expose a resist mask which transfers to a copper or aluminum foil that will be the sound-generating film. [JGJMatt] used a similar technique to put resist on PC board blanks, too. Unfortunately, there were some issues so the finished speakers didn’t use the foil prepared using this method. Instead, a quick modification to the resin printer allowed a thin film of resin to rest on the foil, which was then exposed.

Once you have the pieces, there isn’t much left to do but put them together. Honestly, this is one of those things you probably won’t do yourself unless you are obsessed with speakers. But there were a lot of interesting techniques here that might come in handy, even if you don’t care about audio reproduction.

[JGJMatt] showed us a ribbon speaker before. We have seen some speakers that are practically all 3D printed.

Modern Brownie Camera Talks SD And WiFi

June 11, 2023 by 4 Comments

If you’re at all into nostalgic cameras, you’ve certainly seen the old Brownie from Kodak. They were everywhere, and feature an iconic look. [JGJMatt] couldn’t help but notice that you could easily find old ones at a good price, but finding and developing No. 117 film these days can be challenging. But thanks to a little 3D printing, you can install an ESP32 camera inside and wind up with a modern but retro-stylish camera. The new old camera will work with a memory card or send data over WiFi.

The Brownie dates back to 1900 and cost, initially, one dollar. Of course, a dollar back then is worth about $35 now, but still not astronomical. After cleaning up and tuning up an old specimen, it was time to fire up the 3D printer.

There are also mods to the camera to let it accept an M12 lens. There are many lenses of that size you can choose from. There are a few other gotchas, like extending the camera cable, but it looks like you could readily reproduce this project if you wanted one of your very own.

We’ve seen old cameras converted before. Or, you can just start from scratch.

Broken Pocket Watch Becomes Pocket Sundial

March 17, 2023 by 9 Comments

Pocket watches are all well and good, but they have some caveats. They either need regular rewinding, or they need batteries. Sundials on the other hand need only the light from our One True Sun. [JGJMatt] has just the project to convert your broken or disused pocket watches to the solar way of telling the time.

The key is to replace the clockwork internals and face of the pocket watch with a sundial instead. The first step is to create a face for the watch marked out for sundial use. [JGJMatt] explains how to do this with a variety of CNC, painting, or etching methods. He also explains how to use simple tools to generate a sundial design that’s ideally suited to your geographical location. This includes methods for aligning the sundial to True North or True South with an offset compared to Magnetic North or Magnetic South. This allows the sundial to be as accurate as possible. [JGJMatt] describes the general techniques while also building a sundial of his very own. The resulting piece is a handsome bit of brass with a lovely gnomon standing tall to cast a shadow on the dial.

It’s not a quick way to tell the time, by any means. However, the next time your friends ask you what time it is, and you whip out a compass to line up your sundial, they’re sure to be impressed. We’ve seen some creative sundial designs before, too, and if you’ve been creating your own fancy timepieces, don’t hesitate to let us know on the tipsline!

Audio Amp Puts VFDs To Work In An Unusual Way

December 8, 2022 by 14 Comments

It’s safe to say that most projects that feature a VFD emphasize the “D” aspect more than anything. Vacuum fluorescent displays are solid performers, after all, with their cool blue-green glow that’s just the right look for lots of retro and not-so-retro builds. But that doesn’t mean there aren’t applications that leverage the “V” aspect, such as this nifty audio preamp using VFDs as active components.

The inspiration behind [JGJMatt]’s build came from the Korg Nutube line of VFD-based low-voltage dual-triode vacuum tubes. Finding these particular components a little on the expensive side, [JGJMatt] turned to the old standby DM160 VFD indicator tube, which is basically just a triode, to see how it would fare as an amp. The circuit takes advantage of the low current and voltage requirements of the VFDs — the whole thing runs from a USB boost converter — by wedging them between a 2N3904 input stage and a 2N2007 MOSFET output. There’s a mix of SMD and through-hole components on the custom-etched PCB, with a separate riser card to show off the VFDs a little bit through the front panel of the 3D printed case.

All in all, we find this little amp pretty cool, and we love the way it puts a twist on the venerable VFD. We’ve seen similar VFD amps before, but this one’s fit and finish really pays off.