DIY Vactrols Give MIDI-Controlled Video Distortion

It’s one thing to assemble your own circuits from scratch using off the shelf components. It’s quite another to build the components first, and then build the circuit.

That’s the path [Joris Wegner] took with this video distortion effects box, dubbed PHOSPHOR. One might wonder why you’d want a box that makes a video stream look like playback from a 1980s VHS player with tracking problems, but then again, audio distortion for artistic effect is a thing, so why not video? PHOSPHOR is a USB MIDI device, and therein lies the need for custom components. [Joris] had a tough time finding resistive optoisolators, commonly known as Vactrols and which are used to control the distortion effects. He needed something with a wide dynamic range, so he paired up a bright white LED and a cadmium sulfide photoresistor inside a piece of heat shrink tubing. A total of 20 Vactrols were fabricated and installed on a PCB with one of the coolest silkscreens we’ve ever seen, along with the Sparkfun Pro Micro that takes care of MIDI chores. Now, distortions of the video can be saved as presets and played back in sync with music for artistic effects.

This isn’t the first time Vactrols have made an appearance here, of course. We saw them a while back with this Arduinofied electric guitar, and more recently with a triple-555 timer synth.

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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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Monitoring Power By Counting Blinks

What do you do when you want to add a new feature to some electronics but you can’t or don’t want to tear into the guts? You look for something external with which you can interface. We like these hacks because they take some thinking outside the box, literally and figuratively, and often involve an Aha! moment.

[Simon Aubury’s] big household load was electric heating and his ancient heaters didn’t provide any way to monitor their usage. His power meters weren’t smart meters and he didn’t want to open them up. But the power meters did have an external LED which blinked each time 1 Wh was consumed. Aha! He could monitor the blinks.

Home power usage graph
Maximum is white, average is orange, and minimum is blue.

Doing so was simple enough. Just point photoresistors at the two meter’s LEDs and connect them and capacitors to a Raspberry Pi’s GPIO pins. Every time a pulse is detected, his Python code increments the LED’s counter and every fifteen minutes he writes the counters to an SQL database. Analysing his data he saw that nothing much happens before 5 AM and that the lowest daytime usage is around noon. The maximum recorded value was due to a heater accidentally being left on and the minimum is due to a mini holiday. Pretty good info given that all he had to go on was a blinking light.

Where else are there LED indicators which you can tap into? Here’s an only slightly more invasive usage where a washing machine’s “end of cycle” LED  was removed and the power going to it was rerouted to an Arduino for remote monitoring.

Sushi-Snarfing Barbie Uses Solenoid To Swallow

The view from America has long seen French women as synonymous with thin and/or beautiful. France is well-known for culinary skill and delights, and yet many of its female inhabitants seem to view eating heartily as passé. At a recent workshop devoted to creating DIY amusements, [Niklas Roy] and [Kati Hyyppä] built an electro-mechanical sushi-eating game starring Barbie, American icon of the feminine ideal. The goal of the game is to feed her well and inspire a happy relationship with food.

Built in just three days, J’ai faim! (translation: I’m hungry!) lets the player satiate Barbie one randomly lit piece of sushi at a time. Each piece has a companion LED mounted beneath the surface that’s connected in series to the one on the game board. Qualifying sushi are determined by a photocell strapped to the underside of Barbie’s tongue, which detects light from the hidden LED. Players must race against the clock to eat each piece, taking Barbie up the satisfaction meter from ‘starving’ to ‘well-fed’. Gobble an unlit piece, and the score goes down.

The game is controlled with a lovely pink lollipop of a joystick, which was the main inspiration for the game. Players move her head with left and right, and pull down to engage the solenoid that pushes her comically long tongue out of her button-nosed face. Barbie’s brain is an Arduino Uno, which also controls the stepper motor that moves her head.

[Niklas] and [Kati] wound up using cardboard end stops inside the box instead of trying to count the rapidly changing steps as she swivels around. The first motor they used was too weak to move her head. The second one worked, but the game’s popularity combined with the end stops did a number on the gears after a day or so. Click past the break to sink your teeth into the demo video.

Barbie can do more than teach young girls healthy eating habits. She can also teach them about cryptography.

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Headlight Mod For An Audi A3

If you have a car that is getting on in years, it may be missing some of the latest frills and features that the latest models sport. [Muris] has a slightly dated Audi A3 8P which did not have an AUTO setting for the headlights. In the newer models, this feature turns on the headlights when the ambient light falls below a threshold level (overcast conditions or when going through a tunnel), or when the windshield wipers are turned on. The light sensor is integrated behind the rear view mirror in a special mount, requiring an expensive windshield upgrade if he were to opt for the factory retrofit. Instead, he decided to build his own Automatic Headlights Sensor upgrade for his Audi A3.

His local regulations require the car headlights to be on all the time when the vehicle is in motion. So adding this feature may seem moot at first sight. But [Muris] programmed the headlights to be powered at 70% during daytime conditions and switch to 100% when his sensor detects low ambient light conditions. In the power save mode, all of the other non-essential lights (number plate, tail light) are also turned off to hopefully extend their life. He achieved this by using the VCDS (VAG-COM Diagnostic System) – a widely used aftermarket diagnostics tool for VW-Audi Group vehicles. His tiny circuit switches the lights between the two power settings.

His plan was to install the device without disturbing the original wiring or light switch assembly in any way. The low-powered device consists of a PIC micro-controller, an LDR (light dependent resistor) for light sensing and a low current relay which switches between the two modes. Setting the threshold at which the circuit switches the output is adjusted by a variable trimpot acting as a voltage divider with the LDR. [Muris] wired up a short custom harness which let him install this circuit between the default light switch and the car electronics. After switching on power, he has 15 seconds to enable or disable his unit by toggling the light switch five times, and that status gets stored in memory. The tiny board is assembled using SMD parts and is protected with a heatshrink sleeve. The circuit would work equally well with a lot of other cars, so If you’ve got one which could do with this feature upgrade, then [Muris] has the Eagle CAD files and code available for download on his blog.

Check out the video below where he runs a demo, describes his circuit in detail and then proceeds to assemble the PCB without using a vise or a third hand to hold the PCB. That’s a fancy watch he’s sporting at 00:50 s down the video.

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Pulling Music Out Of Thin Air With A Raspberry Pi

Pianos are great instruments, but being rather heavy and requiring a fair amount of space they are certainly not known for their convenience. Sure, there are more portable varieties available, but they rarely resemble the elegance and classiness of a grand piano. One option is of course to build a downscaled version yourself — and since you’re already customizing the instrument, why stop at the way you play it. [2fishy] didn’t stop there either and ended up with a wooden, space friendly, light controlled piano housing a Raspberry Pi.

Inspired by the concept of a laser harp, [2fishy] followed the same principle but chose a simpler and safer alternative by using LEDs instead. For each playable tone, a LED is mounted opposite a light dependent resistor, creating an array of switches that is then connected to the Raspberry Pi’s GPIO pins. A Python script is handling the rest, polling the GPIO states and — with a little help from pygame, triggering MIDI playback whenever the light stream is interrupted.

There are enough LED/LDR pairs to play one full octave and have some additional control inputs for menu and octave shifting. This concept will naturally require some adjustments to your playing — you can get an idea of it in the demonstration video after the break. And if this design is still not the right size for you, or if you prefer to play in total darkness, this similar MIDI instrument using ultrasonic distance sensors could be of interest.

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Teensy Laser Harp Has Big Sound

[Johan] has slipped down the rabbit hole of making musical instruments. His poison? Laser harp MIDI controllers. Having never made one before, he thought he would start small and then iterate using what he learned. Fortunately for us, [Johan] documented the process over on .io, essentially creating a step-by-step guide for building a simple but powerful 16-note laser harp.

Laser Harp I is built around a Teensy 3.2 and, of course, lasers pointed at LDRs. [Johan] used fairly low-power laser modules, which are slightly less blinding if you accidentally look at them for a second, but should still be taken seriously. He added four potentiometers to control the sensitivity, scale, octave, and the transposition. The sensitivity pot essentially accounts for the ambient light in the room. Although it only has 16 notes, Laser Harp I is ready to rock with over 30 different scales to choose from. Check out the brief demo that [Johan] put up on his Instagram.

If you try to build your own laser harp and get lost trying to follow [Johan]’s instructions, don’t worry. His well-commented code and lovely schematic will undoubtedly save you. Then you can move on to open-beam designs.