Tic Tac Arduintoe Moves The Game To 4×4

May 26, 2020 by Kristina Panos 5 Comments

We know you’re out there spending a lot more time with your loved ones, and appreciate that you may be running out of ways to keep everyone entertained. [Mukesh] dropped us a tip because he has the antidote to boredom — a new twist on that old chestnut, Tic Tac Toe.

Instead of the usual 3×3 configuration, [Mukesh] made the grid 4×4 so the game would be more engaging. Game play is otherwise the same — this Tic Tac Toe still results in a lot of draws, but they take longer and you can’t see them coming a mile away. What’s even more engaging is that you get to push clicky buttons that light up, and don’t have to draw a grid before every game.

Under the hood is an Arduino Uno that controls 16 push buttons and their corresponding RGB LEDs. Whoever goes first is blue, and player two gets pink. If you win, your color floods the board for a brief victory animation. If the game is a tie, the board turns red. We really like the printed two-piece buttons that house the LEDs and actuate the push buttons while keeping the two separate. Toe your way past the break to check out the build video.

Intrigued by the 4×4 version, but need a build that takes more time? Try building your TTT in TTL.

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Secret Knock Unlocks Door

May 25, 2020 by Al Williams 12 Comments

Watch any movie about the years of prohibition, and you’ll probably see character gain admittance to a speakeasy by using a secret knock on the door. In the old movies, a little sliding door would open so the doorman could check you out and let you in. With [IsmailSan’s] electronic lock, the secret knock automatically unlocks the door. You can see a video of how it works, below.

(Ed Note: Grrr…GitHub repo got pulled between writing and publication. Go check out the in-links in the bottom paragraph if you’re interested in knock-detectors.)

The device uses a piezoelectric speaker to detect the knocking. A speaker is a transducer and like many transducers, it will work — to some extent — in either direction. A servo motor manages the deadbolt. An Arduino runs the whole thing.

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Lasercut Puzzlebox Is Safe-Cracking Fun

May 25, 2020 by Lewin Day 3 Comments

If you head out into the real world and start twiddling knobs on random safes, you might find yourself being hauled away by uniformed police. A safer pastime might be playing with your own puzzlebox at home, which is precisely what [thediylife] has done with this build.

The design implements a basic safe-cracking game, in which players try to guess the combination to the safe in a series of rounds. Input is via a rotary encoder, hooked up to the Arduino Uno inside. This project really wins because the finish looks so amazing. The safe is constructed out of 3mm MDF, which is lasercut to shape — an easy one to whip up in the average makerspace. The interface is fleshed out with a small OLED screen and some LEDs, while a servo acts as the lock which holds the door shut. When you see the underside of the face plate with components hot glued into holes you’ll really pale at how clean the business side ended up.

It’s a simple build, and one that would make a great party game with a prize hidden inside. We’ve seen other puzzle-box builds before, too — like the GPS-based reverse geocache build. Video after the break.

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Mimicking Exoplanet Exploration At Home

May 24, 2020 by Sven Gregori 3 Comments

Mankind will always wonder whether we’re alone in the universe. What is out there? Sure, these past weeks we’ve been increasingly wondering the same about our own, direct proximity, but that’s a different story. Up until two years ago, we had the Kepler space telescope aiding us in our quest for answers by exploring exoplanets within our galaxy. [poblocki1982], who’s been fascinated by space since childhood times, and has recently discovered 3D printing as his new thing, figured there is nothing better than finding a way to combine your hobbies, and built a simplified model version simulating the telescope’s main concept.

The general idea is to detect the slight variation of a star’s brightness when one of its planets passes by it, and use that variation to analyze each planet’s characteristics. He achieves this with an LDR connected to an Arduino, allowing both live reading and logging the data on an SD card. Unfortunately, rocket science isn’t on his list of hobbies yet, so [poblocki1982] has to bring outer space to his home. Using a DC motor to rotate two “planets” of different size, rotation speed, and distance around their “star”, he has the perfect model planetary system that can easily double as a decorative lamp.

Obviously, this isn’t meant to detect actual planets as the real Kepler space telescope did, but to demonstrate the general concept of it, and as such makes this a nice little science experiment. For a more pragmatic use of our own Solar System, [poblocki1982] has recently built this self-calibrating sundial. And if you like rotating models of planets, check out some previous projects on that.

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Arduband Gives Your Eyes A Hand

May 24, 2020 by Kristina Panos 14 Comments

Let’s face it, we probably all sit at our computers for way too long without getting up. Yes, there’s work to be done, games to be played, and the internet abounds with people who are wrong and must be down-voted and/or corrected. We totally get and respect all that. However, if you want to maintain your middle- and long-range vision, you should really get up regularly and gaze out the window for a bit.

In fact, the Arduband does you one better. Its Arduino Nano and accelerometer check your position every ten minutes. If you haven’t changed your Z by the third check, then it’s time for a break. The combination of an RGB LED, buzzer, and vibrating disc motor working together should be enough to pull you out of any computerized stupor, and they won’t give up and go back to sleep until you have stood up and remained upright for one minute.

We like that [ardutronics123] spun up a board and made it small enough to be wrist-mounted using a watch strap. It would work just as well worn around your neck, and would probably even fit in your pocket. Blink a few times before you check out the build video after the break.

Arduband would be great on the go, but who does that anymore? If you spend every day at the same desk, you could point a time-of-flight sensor at your chair and start a timer.

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Resistors Sorter Measures Values

May 23, 2020 by Al Williams 22 Comments

We’ve all been there. A big bag of resistors all mixed up. Maybe you bought them cheap. Maybe your neatly organized drawers spilled. Of course, you can excruciatingly read the color codes one by one. Or use a meter. But either way, it is a tedious job. [Ishann’s] solution was to build an automatic sorter that directly measures the value using a voltage divider, rather than rely on machine vision as is often the case in these projects. That means it could be modified to do matching for precise circuits (e.g., sort out resistors all marked 1K that are more than a half-percent away from one nominal value).

There is a funnel that admits one resistor at a time into a test area where it is measured. A plate at the bottom rotates depending on the measured value. In the current implementation, the resistor either falls to the left or the right. It wouldn’t be hard to make a rotating tray with compartments for different values of resistance. It looks like you have to feed the machine one resistor at a time, and automating that sounds like a trick considering how jumbled loose axial components can be. Still, its a fun project that you probably have all the parts to make.

An Arduino powers the thing. An LCD screen and display control the action. If you want some practice handling material robotically, this is a great use of servos and gravity and it does serve a practical purpose.

We have seen many variations on this, including ones that read the color code. If you ever wanted to know where the color code for resistors came from, we took a trip to the past to find out earlier this year.

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An Arduino As A PLL

May 23, 2020 by Jenny List 16 Comments

At the heart of many amateur radio and other projects lies the VFO, or Variable Frequency Oscillator. Decades ago this would have been a free-running LC tuned circuit, then as technology advanced it was replaced by a digital phase-locked-loop frequency synthesiser and most recently a DDS, or Direct Digital Synthesis chip in which the waveform is produced directly by a DAC. The phase-locked loop (PLL) remains a popular choice due to ICs such as the Si5351 but is rarely constructed from individual chips as it once might have been. [fvfilippetti] has revisited this classic circuit by replacing some of its complexity with an Arduino (Spanish language, Google Translate link).

The internals of a PLL frequency synthesiser. Image by Chetvorno – CC0

A PLL is a simple circuit in which one oscillator is locked to another by controlling it with a voltage derived from comparing the phase of the two. Combining a PLL with a set of frequency dividers creates a frequency synthesiser, in which a variable frequency oscillator can be locked to a single frequency crystal with the output frequency set by the division ratios. The classic PLL chip is the CMOS 4046 which would have been combined with a pile of logic chips to make a frequency synthesiser. The Arduino version uses the Arduino’s internal peripherals to take the place of crystal oscillator, dividers, and phase comparator, resulting in an extremely simple physical circuit of little more than an Arduino and a VCO for the 40 metre amateur band. The code can be found on GitLab, should you wish to try for yourself.

It would be interesting to see how good this synthesiser is at maintaining both a steady frequency and minimal phase noise. It’s tempting to think of such things as frequency synthesisers as a done deal, so it’s always welcome to see somebody bringing something new to them. Meanwhile if PLLs are new to you, we have just the introduction for you.