Arduino PLC Keeps The Beat

July 6, 2024 by Bryan Cockfield 12 Comments

For most of our prototype, hobby, or one-off electronics projects it’s perfectly fine to use a development platform like an Arduino Uno or something to that effect. They’re both easy to program and easy to wire up to projects without breaking the bank. But if you step into an industrial setting where reliability is paramount even in places that are noisy, vibrating all the time, hot, or otherwise unpleasant for electronics, you’ll want to reach for a programmable logic controller (PLC) that are much more robust. There is actually a PLC from Arduino, and if you want to dip your toes into the PLC world then take a look at this drum kit based on the Arduino Opta.

With the PLC at the core of the build, it’s on to making the drumming mechanisms themselves. For that, project creator [JC Audio] is using a series of solenoids attached to camera mounts with a custom 3D printed part that allows for quick assembly and disassembly so he can get the positioning of each drum sound just right. The high hat is taken care of by the noise of an internal solenoid, with the other drums striking various real drums and other solid objects in his shops. The solenoids themselves are driven by a solid-state relay expansion module to ensure there’s enough power

While the build doesn’t sit inside a factory and run for years at a time, a musician’s stage is certainly a rough enough environment that we might reach for a PLC over a standard development board for its benefits. The code for this project is available as well at the project’s GitHub page for those looking for a more advanced timekeeper to play along with their music practice, and for more details on why you might choose a PLC for your project take a look at this Arduino vs PLC showdown from a few years ago.

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POV Digital Clock Is The Literal Sands Of Time

May 9, 2024 by Dan Maloney 9 Comments

Sand has been used to keep track of the passage of time since antiquity. But using sand to make a persistence of vision digital clock (English translation) is something altogether new. And it’s pretty cool, too.

The idea behind the timepiece that [Álvaro Gómez Giménez] built is pretty simple drop a tiny slug of fine sand from a hopper and light it up at just the right point in its fall. Do that rapidly enough and you can build up an image of the digits you want to display. Simple in concept, but the devil is in the details. Sand isn’t the easiest material to control, so most of the work went into designing hoppers with solenoid-controlled gates to dispense well-formed slugs of sand at just the right moment. Each digit of the clock has four of these gates in parallel, and controlling when the 16 gates open and close and when the LEDs are turned on is the work of a PIC18F4550 microcontroller.

The build has a lot of intricate parts, some 3D printed and some machined, but all very carefully crafted. We particularly like the big block of clear plastic that was milled into a mount for the main PCB; the translucent finish on the milled surfaces makes a fantastic diffuser for the 96 white LEDs. The clock actually works a lot better than we expected, with the digits easy to make out against a dark background. Check it out in the video below.

Between the noise of 16 solenoids and the sand getting everywhere, we’d imagine it wouldn’t be a lot of fun to have on a desk or nightstand, but the execution is top-notch, and an interesting and unusual concept we haven’t seen before. Sure, we’ve seen sandwriting, but that’s totally different. Continue reading “POV Digital Clock Is The Literal Sands Of Time” →

A Look Inside A 70-GHz Electromechanical Attenuator

March 15, 2024 by Dan Maloney 4 Comments

It might not count as “DC to daylight,” but an electromechanical attenuator that covers up to 70 GHz is pretty close, and getting a guided tour of its insides is quite a treat.

Perhaps unsurprisingly, this one comes to us from [Shahriar] at “The Signal Path,” where high-end gear most of us never get a chance to work with goes for one last hurrah after it releases the magic smoke. And indeed, that appears to be exactly what happened to the Rohde & Schwarz 75 dB step attenuator, a part that may have lived in the front end of one of their spectrum analyzers. As one would expect from such an expensive component, the insides have some pretty special engineering. The signal is carried through the five attenuation stages on a narrow strip of copper. Each stage uses a solenoid to move the strip between either a plain conductor or a small Pi pad with a specified attenuation. The attention to detail inside the cavity is amazing, with great care taken to maintain the physical orientation of the stripline to prevent impedance mismatches and unwanted reflections.

The Pi pads themselves are fascinating, too, especially under [Shahriar]’s super-duper microscope. All of them were destructively removed from the cavity before getting to him, but it’s still pretty clear what’s going on. That’s especially true with the 5-dB pad, which bears clear signs of the overload that brought on the demise of the whole attenuator. We suppose a repair would have been feasible if it had been just the one pad that needed replacement, but with all of them broken, it’s off to the scrap bin. Or to the recycler — there appears to be plenty of gold in there.

We thought this was a fantastic look under the covers of an exquisitely engineered part. Too bad it didn’t rate the [Shahriar] X-ray treatment, as this multimeter repair or this 60-GHz phased array did. Oh, well — maybe next time.

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Sketchy Logg Dogg Logging Robot Remote Control Hacking

February 20, 2024 by Maya Posch 9 Comments

When we last left [Wes] amidst the torn-open guts of his Logg Dogg logging robot, he had managed to revitalize the engine and dug into the hydraulics, but one big obstacle remained: the lack of the remote control unit. In today’s installment of the Logg Dogg series, [Wes] summarizes weeks of agony over creating a custom circuit based around a microcontroller, a joystick and a lot of relays and other bits and pieces to drive the solenoids inside the logging machine that control the hydraulics.

Giving the remote controller a bench test before connecting to the logging robot (Credit: Watch Wes Work)

Most of the struggle was actually with the firmware, as it had to not only control the usual on/off solenoids, but also a number of proportional solenoid valves which control things like the track speed by varying the hydraulic flow to the final drives.

This requires a PWM signal, which [Wes] generated using two MOSFETs in a closed-feedback system, probably because open loop controls with multi-ton hydraulic machinery are not the kind of excitement most people look forward to.

Ultimately he did get it sorted, and was able to take the Logg Dogg for its first walk since being rescued from a barn, which both parties seemed to rather enjoy. The background details of this machine and the project can be found in our first coverage.

We’re looking anxiously forward to the next episode, where the controller goes wireless and the sketchiness gets dialed down some more.

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Recreating The Quadrophonic Sound Of The 70s

February 6, 2024 by Bryan Cockfield 23 Comments

For plenty of media center PCs, home theaters, and people with a simple TV and a decent audio system, the standard speaker setup now is 5.1 surround sound. Left and right speakers in the front and back, with a center speaker and a subwoofer. But the 5.1 setup wasn’t always the standard (and still isn’t the only standard); after stereo was adopted mid-century, audio engineers wanted more than just two channels and briefly attempted a four-channel system called quadrophonic sound. There’s still some media from the 70s that can be found that is built for this system, such as [Alan]’s collection of 8-track tapes. These tapes are getting along in years, so he built a quadrophonic 8-track replica to keep the experience alive.

The first thing needed for a replica system like this is digital quadrophonic audio files themselves. Since the format died in the late 70s, there’s not a lot available in modern times so [Alan] has a dedicated 8-track player connected to a four-channel audio-to-USB device to digitize his own collection of quadrophonic 8-track tapes. This process is destructive for the decades-old tapes so it is very much necessary.

With the audio files captured, he now needs something to play them back with. A Raspberry Pi is put to the task, but it needs a special sound card in order to play back the four channels simultaneously. To preserve the feel of an antique 8-track player he’s cannibalized parts from three broken players to keep the cassette loading mechanism and track indicator display along with four VU meters for each of the channels. A QR code reader inside the device reads a QR code on the replica 8-track cassettes when they are inserted which prompts the Pi to play the correct audio file, and a series of buttons along with a screen on the front can be used to fast forward, rewind and pause. A solenoid inside the device preserves the “clunk” sound typical of real 8-track players.

As a replica, this player goes to great lengths to preserve the essence of not only the 8-track era, but the brief quadrophonic frenzy of the early and mid 70s. There’s not a lot of activity around quadrophonic sound anymore, but 8-tracks are popular targets for builds and restorations, and a few that go beyond audio including this project that uses one for computer memory instead.

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Arduino Auto-Glockenspiel Looks Proper In Copper

December 16, 2023 by Kristina Panos 19 Comments

What is it about solenoids that makes people want to make music with them? Whatever it is, we hope that solenoids never stop inspiring people to make instruments like [CamsLab]’s copper pipe auto-glockenspiel.

At first, [CamsLab] thought of striking glasses of water, but didn’t like the temporary vibe of a setup like that. They also considered striking piano keys, but thought better of it when considering the extra clicking sound that the solenoids would make, plus it seemed needlessly complicated to execute. So [CamsLab] settled on copper pipes.

That in itself was a challenge as [CamsLab] had to figure out just the right lengths to cut each pipe in order to produce the desired pitch. Fortunately, they started with a modest 15-pipe glockenspiel as a proof of concept. However, the most challenging aspect of this project was figuring out how to mount the pipes so that they are close enough to the solenoids but not too close, and weren’t going to move over time. [CamsLab] settled on fishing line to suspend them with a 3D-printed frame mounted on extruded aluminium. The end result looks and sounds great, as you can hear in the video after the break.

Of course, there’s more than one way to auto-glockenspiel. You could always use servos.

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A Fully-Transparent Air Bubble Display

December 6, 2023 by Kristina Panos 5 Comments

We all have good intentions when starting a new project, but then again, we all know where those lead. Such is the case with [RealCorebb]’s BBAir project, a completely transparent air bubble display. Although the plan was to spend about three months on it, the months slowly added up to a full year of tinkering.

It all started when [RealCorebb] made a subscriber counter using Minecraft campfire smoke to display the digits. Someone suggested using air to implement the next iteration, and for [RealCorebb], it was challenge accepted. After considering a syringe for each channel, a separate pump, or one pump and many solenoids, [RealCorebb] settled on solenoids to push air, and designed a PCB to reduce the amount of wire spaghetti.

Once [RealCorebb] created an acrylic enclosure and wired everything up, it was time to test it out. Everything worked, except that air was leaking from somewhere, which turned out to be the way the solenoids were installed. Then, of course, it was time to don sunglasses and write the code. We still don’t know if [RealCorebb] settled on water, glycerine, or silicone oil, but the end result is quite nice, and we’re betting on glycerine. Be sure to check out the build video after the break, which has English subtitles.

Although we’ve seen our share of bubble displays before, we often discuss bubble LEDs displays like this one.

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