IoT Safe Keeps Latchkey Kids’ Phones On Lockdown

Phones are pretty great. Used as telephones, they can save us from bad situations and let us communicate while roaming freely, for the most part. Used as computers, they often become time-sucking black holes that can twist our sense of self and reality. Assuming they pick up when you call, phones are arguably a good thing for kids to have, especially since you can hardly find a payphone these days. But how do you teach kids to use them responsibly, so they can still become functioning adults and move out someday? [Jaychouu] believes the answer is inside of a specialized lockbox.

This slick-looking box has a solenoid lock inside that can be unlocked via a keypad, or remotely via the OBLOQ IoT module. [Jaychouu] added a few features that drive it out of Arduino lockbox territory. To prevent latchkey children from cheating the system and putting rocks (or nothing at all) in the box, there’s a digital weight sensor and an ultrasonic sensor that validate the credentials of the contents and compare them with known values.

Want a basic lockbox to keep your phone out of reach while you work? Here’s one with a countdown timer.

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Superbly Synchronized Servos Swaying Softly

LEDs and blinky projects are great, and will likely never fade from our favor. But would you look at this sweeping beauty? This mesmerizing display is made from 36 micro servos with partial Popsicle sticks pasted on the arms. After seeing a huge display with 450 servos at an art museum, [Doug Domke] was inspired to make a scaled-down version.

What [Doug] didn’t scale down is the delightful visuals that simple servo motion can produce. The code produces a three-minute looping show that gets progressively more awesome, and you can stare at that after the break. Behind the pegboard, a single, hardworking Arduino Uno controls three 16-channel PWM controllers that sweep the servos. We like to imagine things other than Popsicle sticks swirling around, like little paper pinwheels, or maybe optical illusion wheels for people with strong stomachs.

You won’t see these in the video, but there are five ultrasonic sensors mounted face-up on the back of the pegboard. [Doug] has optional code built in to allow the servo sticks to follow hand movement. We hope he’ll upload a demo of that feature soon.

Servos can be hypnotic as well as helpful, as we saw in this 114-servo word clock.

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Arduino Bot Rocks A PS2 Controller

As far as controlling robots goes, makers today are spoilt for choice. WiFi and Bluetooth enabled microcontrollers are a dime a dozen, and integration with smartphone apps is a cinch. Despite this, the old methods still hold sway, as [Igor Fonseca] demonstrates with a simple Arduino bot.

It’s a classic build, using a tracked chassis with a pair of motors providing propulsion and skid steering. The motors are controlled by an L298N H-bridge board, with power courtesy of a trio of 18650 batteries. An Arduino Uno acts as the brains of the operation. Control is via a Playstation 2 controller, in this case a 2.4 GHz third party version. This allows the robot to be controlled wirelessly, with the decoding handled by [Bill Porter]’s useful Arduino library.

It’s a cheap approach to building a remote-controlled bot, and one that would be a great way to teach interested children about how to work with embedded systems. We’ve featured a similar build before, too. Video after the break.

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Air Hockey Table Is A Breeze To Build

Many of us have considered buying an air hockey table, but are put off by the price. And even if the money is there, those things take up a lot of space. How often are you really going to use it?

This DIY air hockey table is the answer. It’s big enough to be fun, but small and light enough to easily stow away in the off-season. At ~$50, it’s a cheap build, provided you have a vacuum cleaner that can switch to blower mode. The strikers, goals, corner guards, and scoreboard enclosure are all 3D-printed, while the pucks and playfield are laser-cut acrylic. [Technovation] glued acrylic feet to the strikers to help them last longer.

The scoreboard is an Arduino Uno plus an LCD that changes color to match the current winner. Scoring must be entered manually with button presses, but we think it would be fairly easy to detect a puck in the goal with a force or weight sensor or something. For now, the RGB LEDs around the edge are controlled separately with a remote. The ultimate goal is to make the Arduino do it. Shoot past the break and cross-check it out.

Already have a table? Had it so long, no one will play you anymore? Build yourself a robotic opponent.

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LED Matrix And A Phototransistor Make A Reverse Camera

A digital camera has an array of sensors that captures light reflected or transmitted onto it. This build is something closer to a reverse camera – a single sensor that makes images on a matrix of LEDs. And we think it’s pretty neat.

We have to admit to being a little confused by [marciot]’s LED matrix scanner when we first stumbled upon it. From the video below we thought that the LEDs in the matrix were being used both to detect incident light and as a display. We’ve seen LEDs used as photodiodes before, so such a contraption could work, but that’s not what’s going on here. A phototransistor is wired to an Arduino Uno and positioned above a 32×32 RGB LED matrix. A scanning routine rasters over the LEDs in the matrix while the sensor watches, and then the program turns on the LEDs that the sensor saw during the scan. Positioned far above the matrix, a large disc of light results, making it look like the phototransistor is beaming light down onto the matrix. The effect is reinforced by placing something between the sensor and the matrix, which casts a virtual shadow. Used close to the LEDs the sensor acts more like a light pen.

It’s a cool effect and it looks like a fun project to throw together. Refresh time could perhaps be a bit snappier, though; maybe an ESP32 could help with that.

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Talking Washer Is A Clean Solution For The Visually Impaired

Have you shopped for an appliance lately? They’re all LEDs, LEDs everywhere. You might say that manufacturers are out of touch with the utility of tactile controls. [Wingletang]’s fancy new washing machine is cut from this modern cloth. While it does have a nice big knob for selecting cycles, the only indication of your selection is an LED. This isn’t an issue for [Wingletang], but it’s a showstopper for his visually impaired wife.

They tried to make tactile signposts for her most-used cycles with those adhesive rubber feet you use to keep cabinet doors quiet. But between the machine’s 14(!) different wash cycles and the endlessly-rotating selector knob, the tactile map idea was a wash. It was time to make the machine talk.

For his very first microcontroller project, [Wingletang] designed a completely non-invasive and totally awesome solution to this problem. He’s using LDRs arranged in a ring to detect which LED is lit. Recycled mouse pad foam and black styrene keep ambient light from creating false positives, and double as enclosure for the sensor and support boards. As [Mrs. Wingletang] cycles through with the knob, an Arduino clone mounted in a nearby project box determines which program is selected, and a Velleman KA02 audio shield plays a recorded clip of [Wingletang] announcing the cycle number and description.

The system, dubbed SOAP (Speech Output Announcing Programmes), has been a great help to [Mrs. Wingletang] for about the last year. Watch her take it for a spin after the break, and stick around for SOAP’s origin story and walk-through videos.

It’s baffling that so few washers and dryers let you know when they’re finished. Don’t waste your time checking over and over again—Laundry Spy waits for the vibrations to end and sends you a text.

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Driving A Controllerless LCD With The Humble Arduino Uno

These days, you could be forgiven for thinking driving an LCD from a microcontroller is easy. Cheap displays have proliferated, ready to go on breakout boards with controllers already baked in. Load up the right libraries and you’re up and running in a matter of minutes. However, turn your attention to trying to drive a random LCD you’ve yanked out of a piece of old equipment, and suddenly things get harder. [Ivan Kostoski] was in just such a position and decided to get down to work.

[Ivan]’s LCD was a 320×240 STN device salvaged from an old tape library. The display featured no onboard controller, and the original driver wasn’t easily repurposed. Instead, [Ivan] decided to drive it directly from an Arduino Uno.

This is easier said than done. There are stringent timing requirements that push the limits of the 8-bit platform, let alone the need for a negative voltage to drive the screen and further hardware to drive the backlight. These are all tackled in turn, with [Ivan] sharing his tips to get the most flexibility out of the display. Graphics and text modes are discussed, along with optimizations that could be possible through the varied use of available RAM and flash.

The code is available on Github. If you need inspiration for your own controllerless LCD driver. [Ben Heck] has done similar work too, using FPGA grunt to get the job done.