Rodriguez — IV Curve Tracer On The Cheap

May 16, 2021 by Chris Lott 9 Comments

In response to an online discussion on the Electrical Engineering Stack Exchange, [Joseph Eoff] decided to prove his point by slapping together a bare-bones IV curve tracer using an Arduino Nano and a handful of passives. But he continued to tinker with the circuit, seeing just how much improvement was possible out of this simple setup. He squeezes a bit of extra resolution out of the PWM DAC circuit by using the Timer1 library to obtain 1024 instead of 256 steps. For reading voltages, he implements oversampling (and in some cases oversampling again) to eke out a few extra bits of resolution from the 10-bit ADC of the Nano. The whole thing is controlled by a Python / Qt script to generate the desired plots.

While it works and gives him the IV curves, this simplicity comes at a price. It’s slow — [Joseph] reports that it takes several minutes to trace out five different values of base current on a transistor. It was this lack of speed that inspired him to name the project after cartoon character Speedy Gonzales’s cousin, Slowpoke Rodriguez, AKA “the slowest mouse in all of Mexico”. In addition to being painstakingly slow, the tracer is limited to 5 volts and currents under 5 milliamps.

[Joseph] documents the whole design and build process over on his blog, and has made the source code available on GitHub should you want to try this yourself. We covered another interesting IV curve tracer build on cardboard ten years ago, but that one is much bigger than the Rodriguez.

A Phased-Array Ultrasonic 3D Scanner From Scratch

May 15, 2021 by Jenny List 6 Comments

Who wouldn’t want an autonomous drone to deliver cans of fizzy drink fresh from the fridge? [Alex Toussaint] did, and in thinking how such a machine might work he embarked on a path that eventually led him to create a fully functional ultrasonic 3D scanner. In writing it up he’s produced a straightforward description of how the system works, which should also be of interest to anyone curious about phased array radar. He starts with an easy-to-understand explanation of the principle behind phased array beam forming, and there follows his journey into electronics as he uses this ambitious project to learn the art from scratch. That he succeeded is testament to his ability as well as his sheer tenacity.

He finally arrived at a grid of 100 ultrasonic emitters controlled from an Arduino through a series of shift register boards. Using this he can steer his ultrasonic beam horizontally as well as vertically, and receive echoes from objects in three-dimensional space. The ornamental bird example he uses for his scanning tests doesn’t quite emerge in startling clarity, but it is still clear that an object of its size and rough shape is visible enough for the drone in his original idea to detect it. If you would like to experiment with the same techniques and array then all the resources can be found in a GitHub repository, meanwhile we’re still impressed with the progress from relative electronics novice to this. We hope the ideas within it will be developed further.

We’ve seen ultrasonic arrays before, but mainly used in levitation experiments.

Go Ape With A Banana Macropad

May 14, 2021 by Kristina Panos 14 Comments

The super fun thing about macro pads is that they’re inherently ultra-personalized, so why not have fun with them? This appealing little keeb may have been a joke originally, but [dapperrogue] makes a valid point among a bunch of banana-related puns on the project page — the shape makes it quite the ergonomic little input device.

Inside this open-source banana is that perennial favorite for macro pads, the Arduino Pro Micro, and eight switches that are wired up directly to input pins. We’re not sure what flavor of Cherry those switches are, hopefully brown or green, but we suddenly wish Cherry made yellow switches. If you want to build your own, the STLs and code are available, and we know for a fact that other switch purveyors do in fact make yellow-stemmed switches.

Contrary to what the BOM says, we believe the sticker is mandatory because it just makes the build — we imagine there would be fewer double takes without it. Hopefully this fosters future fun keyboard builds from the community, and we can’t wait to sink our teeth into the split version!

There are a bunch of ways to make a macropad, including printing everything but the microcontroller.

Via r/mk and KBD

Realistic Mission Control Box Is A Blast For All Ages

May 13, 2021 by Kristina Panos 19 Comments

A lot of electronic busy boxes that are built for children are simply that — a mess of meaningless knobs and switches that don’t do much beyond actuating back and forth (which, let’s be honest, is still pretty fun to do). But this Mission Control Center by [gcall1979] knocks them all out of orbit. The simulation runs through a complete mission, including a 10-minute countdown with pre-flight system checks, 8.5 minutes of powered flight to get out of the atmosphere that includes another four tasks, and 90 minutes to orbit the Earth while passing through nine tracking stations across the world map.

That’s a lot time to keep anyone’s attention, but fortunately [gcall1979] included a simulation speed knob that can make everything go up to 15 times faster than real-time. This knob can be twiddled at any time, in case you want to savor the countdown but get into space faster, or you don’t have 90 minutes to watch the world map light up.

The main brain of this well-built box is an Arduino Mega, which controls everything but the launch systems’ mainframe computer — this is represented by bank of active LEDs that blink along with the voice in the sound clips and runs on an Arduino Uno and a couple of shift registers. To keep things relatively simple, [gcall1979] used an Adafruit sound board for the clips.

We love everything about this build, especially the attention to detail — the more important pre-flight tasks are given covered toggle switches, and there’s a Shuttle diagram that lights up as each of these are completed. And what Shuttle launch simulator would be complete without mushroom buttons for launch and abort? Grab your victory cigar and check out the demo video after the break.

Is your child too young to be launching the Shuttle? Here’s an equally cool busy box with toddler brains in mind.

Continue reading “Realistic Mission Control Box Is A Blast For All Ages” →

Piggy Bank Slot Machine Puts A Spin On Saving

May 12, 2021 by Kristina Panos 7 Comments

Saving money is inherently no fun until the time comes that you get to spend it on something awesome. Wouldn’t you be more likely to drop your coins into a piggy bank if there was a chance for an immediate payout that might exceed the amount you put in? We know we would. And the best part is, if you put such a piggy bank slot machine out in the open where your friends and neighbors can play with it, you’ll probably make even more money. As they say, the house always wins.

Drop a coin in the slot and it passes through a pair of wires that act as a simple switch to start the reels spinning. Inside is an Arduino Uno and a giant printed screw feeder that’s driven by a small stepper motor and a pair of printed gears. The reels have been modernized and the display is made of four individual LED matrices that appear as a single unit thanks to some smoky adhesive film.

This beautiful little machine took a solid week of 3D printing, which includes 32 hours wasted on a huge piece that failed twice. [Max 3D Design] tried rotating the model 180° in the slicer and thankfully, that solved the problem. Then it was on to countless hours of sanding, smoothing with body filler, priming, and painting to make it look fantastic.

If you want to make your own, all the files are up on Thingiverse. The code isn’t shown, but we know for a fact that Arduino slot machine code is out there already. Check out the build and demo video after the break.

As much as we like this build’s simplicity, it would be more slot machine-like if there was a handle to pull. Turns out you can print those, too.

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Leap Motion Controls Hands With No Glove

May 8, 2021 by Al Williams No comments

It isn’t uncommon to see a robot hand-controlled with a glove to mimic a user’s motion. [All Parts Combined] has a different method. Using a Leap Motion controller, he can record hand motions with no glove and then play them back to the robot hand at will. You can see the project in the video, below.

The project seems straightforward enough, but apparently, the Leap documentation isn’t the best. Since he worked it out, though, you might find the code useful.

An 8266 runs everything, although you could probably get by with less. The Leap provides more data than the hand has servos, so there was a bit of algorithm development.

We picked up a few tips about building flexible fingers using heated vinyl tubing. Never know when that’s going to come in handy — no pun intended. The cardboard construction isn’t going to be pretty, but a glove cover works well. You could probably 3D print something, too.

The Unity app will drive the hand live or can playback one of the five recorded routines. You can see how the record and playback work on the video.

This reminded us of another robot hand project, this one 3D printed. We’ve seen more traditional robot arms moving with a Leap before, too. Continue reading “Leap Motion Controls Hands With No Glove” →

Auto Strummer Can Plectrum The Whole Flat-Strumming Spectrum

May 7, 2021 by Kristina Panos 3 Comments

Playing the guitar requires speed, strength, and dexterity in both hands. Depending on your mobility level, rocking out with your axe might be impossible unless you could somehow hold down the strings and have a robot do the strumming for you.

[Jacob Stambaugh]’s Auto Strummer uses six lighted buttons to tell the hidden internal pick which string(s) to strum, which it does with the help of an Arduino Pro Mini and a stepper motor. If two or more buttons are pressed, all the strings between the outermost pair selected will be strummed. That little golden knob near the top is a pot that controls the strumming tempo.

[Jacob]’s impressive 3D-printed enclosure attaches to the guitar with a pair of spring-loaded clamps that grasp the edge of the sound hole. But don’t fret — there’s plenty of foam padding under every point that touches the soundboard.

We were worried that the enclosure would block or muffle the sound, even though it sits about an inch above the hole. But as you can hear in the video after the break, that doesn’t seem to be the case — it sounds fantastic.

Never touched a real guitar, but love to play Guitar Hero? There’s a robot for that, too.

Continue reading “Auto Strummer Can Plectrum The Whole Flat-Strumming Spectrum” →