Fix Old Caps, But Keep That “Can Capacitor” Look

July 30, 2022 by Donald Papp 21 Comments

Vintage electronics and capacitor replacements tend to go hand-in-hand. Why? Because electrolytic capacitors just don’t last, not the way most other components do, anyway.

The metal terminal ring and the central plate are kept for re-use, and the metal case re-crimped after the internals of the capacitor are replaced with a modern equivalent.

It’s one thing to swap old caps with modern replacements, but what about electronics where the components are not hidden away, and are an important part of the equipment’s look? [lens42] shares a method for replacing antique can-style capacitors in a way that leaves them looking completely original. All it takes is some careful application of technique.

The first thing to do is carefully file away the crimp of the metal can until one can release the ring and plate that hold the terminals. Once that is off, the internals can be pulled from the metal can for disposal. Since the insides of the old cap won’t be re-used, [lens42] recommends simply drilling a hole, screwing in a lag bolt to use as a handle, and pulling everything out. There’s now plenty of space inside the old can to hold modern replacements for the capacitor, and one can even re-use the original terminals.

That leaves the job of re-crimping the old can around the terminal ring to restore a factory-made appearance. To best do this, [lens42] created a tapered collar. Gently hammering the can forces the bottom into the taper, and the opening gradually crimps around the terminal ring. It’s also possible to carefully hammer the flange directly, but the finish won’t be as nice. This new crimp job may not look exactly the same as before, but once the cap is re-installed into the original equipment, it won’t be possible to tell it has been modified in any way.

If this sounds a bit intimidating, don’t worry. [lens42] provides plenty of pictures. And if this kind of thing is up your alley, you may want to check out the Caps Wiki, an effort to centralize and share details about tech repair, especially for vintage electronics.

Custom Raspberry Pi Case Shows The Whole Workflow

July 25, 2022 by Donald Papp 29 Comments

If you are a process junkie and love seeing the end-to-end of how a thing is made and with what tools, then watch [Michael Klements] show off his Raspberry Pi case design. His case has quite a few cool-looking elements to it, and incorporates 3D printing as well as laser-cut and clear bent acrylic for a gorgeous three-quarter view.

[Michael]’s write-up (and accompanying video, embedded below) are partly a review of his Creality 3D printer, and partly a showcase of his Raspberry Pi case design (for which he sells the design files for a small fee on his Etsy store.) But the great part is seeing the creation of every piece that goes into the end product. Not everyone is familiar with the way these tools work, or what they can create, so it’s nice to see attention paid to that side of things.

Both the blog post and the video nicely show off what goes into every part. The video opens with unpacking and setting up the 3D printer (skip ahead to 4:58 if you aren’t interested), followed by printing the parts, laser-cutting the acrylic on a K40 laser cutter, bending the acrylic using a small hand tool, and finally, assembling everything. For the curious, there are also links to the exact parts and equipment he uses.

Like we said, it’s part 3D printer review and part showcase of a design he sells, but it’s great to see each of the parts get created, watch the tools get used, and see the results come together in the final product. And should you wish to go in the opposite direction? A one-piece minimalist case for your Raspberry Pi is only a 3D printer away.

Continue reading “Custom Raspberry Pi Case Shows The Whole Workflow” →

Complex Movements From Simple Inflatables, Thanks To Physics

July 24, 2022 by Donald Papp 5 Comments

Inflatable actuators that change shape based on injected pressure can be strong, but their big limitation is that they always deform in the same way.

The Kresling pattern, which inspired the actuator design.

But by taking structural inspiration from origami, researchers created 3D-printed actuators that show it is possible to get complex movements from actuators fed by only a single source of pressure. How is this done? By making the actuators physically bi-stable, in a way that doesn’t require additional sources of pressure.

The key is a modified design based on the Kresling pattern, with each actuator having a specially-designed section (the colored triangles in the image above) that are designed to pop out under a certain amount of positive pressure, and remain stable after it has done so. This section holds its shape until a certain amount of negative pressure is applied, and the section pops back in.

Whether or not this section is popped out changes the actuator’s shape, therefore changing the way it deforms. This makes a simple actuator bi-stable and capable of different movements, using only a single pressure source. Stack up a bunch of these actuators, and with careful pressure control, complex movements become possible. See it in action in two short videos, embedded just below the page break.

Continue reading “Complex Movements From Simple Inflatables, Thanks To Physics” →

Digital “Toy” Camera, Made For Tilt-Shift And Other Analog-Like Experimenting

July 23, 2022 by Donald Papp 5 Comments

Like many others, [volzo] loves playing with photography in a playful and experimental way. Oddball lenses, vintage elements, and building from kits is what that world looks like. But that kind of stuff is really the domain of film cameras, or at least it was until [volzo] created his Digital Toy Camera design. The result? A self-built, lomography-friendly digital camera that allows for all kinds of weird and wonderful attachments and photo shenanigans.

3D-printed mounts and magnetic attachment makes swapping parts a breeze.

To make a DIY digital camera that allowed that kind of play, the first problem [volzo] had to solve was deciding on an image sensor. It turns out that sourcing image sensors as an individual is a pretty cumbersome process, and even if successful, one still needs to write a driver and create things from the ground up. So, the guts of [volzo]’s creations use the Raspberry Pi and camera sensor ecosystem and M12 lenses, a decision that allows him to focus on the rest of the camera.

3D printing, a bit of CNC machining, and some clever design yields a “toy” camera: simple, inexpensive, and enabling one to take a playful and experimental approach to photography. The design files are available on GitHub, and there are some neat elements to the design. Magnetic mounts allow for easy swapping of lens assemblies, and a M12 x 0.75 tap cuts perfect threads into 3D-printed pieces for M12 lenses.

Heat-set inserts also provide robust fastening that can hold up to disassembly and re-assembly (and don’t miss that our own [Joshua Vasquez] has shared how best to design for and use heat-set inserts.)

[volzo] has a fantastic video to accompany his project; give it a watch (embedded below, under the page break) and see if you don’t come away with some inspiration of your own.

Continue reading “Digital “Toy” Camera, Made For Tilt-Shift And Other Analog-Like Experimenting” →

Restoring $5 Busted Synthesizer Made Easy, Thanks To Thermal

July 16, 2022 by Donald Papp 19 Comments

[D. Scott Williamson] paid $5 for a Roland JV-30 synthesizer at a garage sale. Score! There was only one catch: it didn’t work and didn’t include the power supply. Luckily, restoring it was made easier by breaking out a thermal camera.

As mentioned, the keyboard was missing a 9 VDC power supply (rated 800 mA) with a center-negative barrel connector. Slightly oddball, but nothing an enterprising hacker can’t deal with. After supplying power with a bench supply, not only did the keyboard not come to life, but the power supply clamped the current draw at 1.5 A! Something was definitely not right.

This shorted glass-bodied diode might look normal to the naked eye, but thermal imaging makes it clear something’s amiss.

Inside, there was no visible (or olfactory) sign of damage, but looking closer revealed that a little SMT capacitor by the power connector was cracked in two. Fixing that didn’t bring the keyboard to life, so it was time to break out the thermal imager. Something was soaking up all that current, and it’s a fair bet that something is getting hot in the process.

The culprit? The reverse polarity protection diode was shorted, probably as a result of damage by an inappropriate power supply or a surge of some kind. Replacing it resulted in a working keyboard! Not bad at all for $5, a diode, an SMT cap, and a little workbench time. The finishing touch was replacing a missing slider knob, which took some work in OpenSCAD and a 3D printer. Overall, not bad!

Thermal imaging used to be the stuff of staggering price tags, but it’s downright accessible these days, and makes it easy to spot things that are hot when they shouldn’t be. And if a thermal camera’s lens isn’t what you think it should be? It’s even possible for a sufficiently motivated and knowledgeable hacker to modify those.

Got A Cardboard Box? Get Into Food Smoking!

July 15, 2022 by Donald Papp 17 Comments

We appreciate a good kitchen hack, and we have always liked TV personality and chef [Alton Brown]’s McGuyver-ish approach to these things. So for anyone who hasn’t seen it, let’s take a moment to highlight how to make (and use) Alton Brown’s Cardboard Box Smoker.

[Alton] himself confesses that over the years it has remained his favorite smoker for a few good reasons. The price is certainly right, but there are a few other things that really stand out in the design. It’s easy to assemble and take down, needing very little storage space compared to a purpose-built smoker. It’s also trivial to monitor the temperature inside: just poke a thermometer probe through the side of the box. Finally, it’s a great way to get some additional use out of an old hot plate and cast iron pan. It’s the kind of thing one could put together from a garage sale and a visit to the dollar store.

The cardboard box is perfectly serviceable, but one may be tempted to kick it up a notch with some upgrades. In that case, check out this tech-upgraded flower pot smoker (also based on an Alton Brown design.)

Reusing and repurposing is a great way to experiment in the kitchen without needing to buy specialized equipment. Here’s another example: Kyoto-style cold brew coffee. It’s thick and rich and brings out different flavor profiles. Curious? Well, normally it requires a special kind of filter setup, but it can also be accomplished with cheesecloth, coffee filters, and a couple of cut-up soft drink bottles. Oh, and some rubber bands and chopsticks if things are too wobbly. Just do yourself a favor and use good quality coffee beans, or better yet, roast them yourself. Just trust us on this one.

When Combat Robot Wheels Need To Be Nice And Cheap (But Mostly Cheap)

July 10, 2022 by Donald Papp 11 Comments

It started with [CHORL] making a promise to himself regarding constructing a new combat robot: no spending of money on the new robot.

That rule was violated (but only a little) by making his robot’s wheels out of EVA kneeling pads. EVA (Ethylene-Vinyl Acetate) is a closed-cell foam that makes for durable yoga mats, kneeling pads, and products of a similar nature. [CHORL] found a way to turn them into light but serviceable wheels for his robot: the Susquehanna Boxcar.

Nested hole saws create concentric holes. Perfect for wheels.

Here’s how the wheels were made: [CHORL] began with two hole saws. Nesting a smaller hole saw into a larger one by putting both on the same arbor created a saw with two holes, both of which were centered with respect to one another. The only problem was that this hole saw was not actually deep enough to cut completely through the thick foam. Luckily, cutting roughly halfway through on one side, then flipping the sheet over and cutting through from the other side was a good workaround. That took care of turning the thick foam sheet into round wheels.

A 3D-printed part served as a wheel hub as well as gear for the drivetrain. We want to call attention to the clever method of reinforcing the connection between the parts. [CHORL] didn’t want to just glue the geared hub directly to the surface of the foam wheel, because he suspected it might separate under stress. To address this, he designed six slots into the hub, cut matching slots into the foam wheel, and inserted six spline-like reinforcements in the form of some ABS strips he had on hand. Gluing it all together with E-6000 and leaving it to cure overnight under a weight resulted in a geared wheel assembly that [CHORL] judged to be about as round and rigid as a wheel should be, so the robot had a solution for nice light wheels that were, above all, cheap!

Lots of robots need wheels, and unsurprisingly, DIY solutions are common projects. [CHORL]’s approach here looks pretty scalable, as long as one can cut some accurate holes.

Interested in knowing more about the robot these wheels are destined for? [CHORL]’s still working on the Susquehanna Boxcar, but it’s almost done, and you can read a bit more about it (and see a few more pictures) here.