Silicone Tubing As Springs For Capacitive Touch Buttons

December 23, 2024 by Maya Posch 7 Comments

Capacitive touch buttons are a great way to turn just about any (non-conductive) surface into a button, but people generally dislike the lack of tactile feedback. [KontinuumLab] apparently agreed and decided to experiment a bit with ways to make such buttons more springy. You can check out the results of those experiments in the video below. There are a few ways to add some spring to buttons and switches like these, including compliant mechanisms in the (3D-printed) plastic structure, but this isn’t always an option in a project. A separate plastic spring can be added, but they aren’t very durable. A metal spring works great but can be a bit of a hassle to integrate and they aren’t as cheap as the other options. So what about everyone’s favorite keyboard switch, the rubber dome type?

Silicone tubing is plentiful and (generally) cheap. It can be selected for just the right springiness and dimensions, and in the automated test that [KontinuumLab] ran, it is also very durable in this application. When your goal is to have a switch that activates at the end of the travel, this may work a treat, with the size of the silicone tube determining the travel before the finger gets close enough to trigger the switch. As rubber dome keyboards demonstrate, this is a highly reliable technology, though this version ditches the typical membrane for the capacitive touch sensor.

Sometimes, a metal spring is the right option, of course, such as when you want to make a surface a touch sensor and the PCB is at the other side of the enclosure. The fun part is that we have all of these options to make our projects work, with many being very affordable to hobbyists. Not all touch sensors require a finger, either.

Thanks to [BrightBlueJim] for the tip.

Continue reading “Silicone Tubing As Springs For Capacitive Touch Buttons” →

MIDI Spoon Piano Is Exactly What You Think It Is

May 16, 2024 by Lewin Day 6 Comments

Pianos traditionally had keys made out of ivory, but there’s a great way to avoid that if you want to save the elephants. You can build a keyboard using spoons, as demonstrated by [JCo Audio].

The build relies on twelve metal spoons to act as the keys of the instrument. They’re assembled into a wooden base in a manner roughly approximating the white and black keys of a conventional piano keyboard, using 3D-printed inserts to hold them in place. They’re hooked up to a Raspberry Pi Pico via a Pico Touch 2 board, which allows the spoons to be used as capacitive touch pads. Code from [todbot] was then used to take input from the 12 spoons and turn it into MIDI data. From there, hooking the Pi Pico up to a PC running some kind of MIDI synth is enough to make sounds.

It’s a simple build, but a functional one. Plus, it lets you ask your friends if they’d like to hear you play the spoons. The key here is to make a big show of hooking your instrument up to a laptop while explaining you’re not going to play the spoons a la the folk instrument, but you’re going to play a synth instead. Then you should use the spoon keyboard to play emulated spoon samples anyway. It’s called doubling down. Video after the break.

Continue reading “MIDI Spoon Piano Is Exactly What You Think It Is” →

A capacitive touch MIDI instrument that doubles as a bookmark.

MIDI Bookmark Marks The Spot Where Work And Play Intersect

May 6, 2024 by Kristina Panos 3 Comments

Have you ever wanted to take a break from reading or studying to just rock out for a few blissful minutes? If you’re anything like us, you like to rock out most of the time and take the occasional break to do your reading. Either way, you really can’t go wrong with this MIDI bookmark from [Misfit Maker].

This slick little bookmark may look 3D printed, but it’s all carefully-cut foam board in two thicknesses. Even the keys are made foam board — they’re just wrapped in carbon fiber so they look extra cool.

Underneath that carbon fiber is a layer of aluminium tape to make them capacitive. [Misfit Maker] recommends using copper tape instead because it allows for wires to be soldered directly to the keys.

The brains of this beauty is in the form of an ESP32 which is controlling an MPR-121 capacitive touch sensor. If you’d like to make one of these for yourself, there are plenty of helpful GIFs embedded in the thorough write-up. Be sure to check out the brief demo after the break.

If you want to easily MIDI-fy something and use touch inputs, you can’t really go wrong with the Raspberry Pi Pico, which does capacitive touch natively. Check out this MIDI kalmiba to learn more.

Continue reading “MIDI Bookmark Marks The Spot Where Work And Play Intersect” →

The board in question, with a Pi Pico soldered on, with old PCBs for macropads being used as captouch electrodes

Give Your Pi Pico Captouch Inputs For All Your Music Needs

March 31, 2024 by Arya Voronova 11 Comments

Unlike many modern microcontrollers, RP2040 doesn’t come with a native capacitive touch peripheral. This doesn’t mean you can’t do it – the usual software-driven way works wonderfully, and only requires an external pullup resistor! In case you wanted a demonstration or you have a capacitive touch project in mind, this lighthearted video by [Jeremy Cook] is a must watch, and he’s got a healthy amount of resources for you in store, too!

In this video, [Jeremy] presents you with a KiCad schematic and an PCB design you can use to quickly add whole 23 capacitive touch sensing inputs to a Pi Pico! The board is flexible mechanically, easy to assemble as [Jeremy] demonstrates, and all the pins involved can still be used as regular GPIOs if you’d like. Plus, it’s fully open-source, can easily be assembled on your own, and available on Tindie too!

Of course, such a board doesn’t get created for no reason – [Jeremy] has a healthy amount of musical creations and nifty ideas to show off. We quite liked the trick of using old PCBs as capacitive touch sensing, using copper fills as electrodes – which has helped create an amusing “macropad of macropads”, and, there’s quite a bit more to see.

If capacitive touch projects ever struck a chord with you and you enjoy music-related hacking, [Jeremy]’s got a whole YouTube channel you ought to check out. Oh, and if one of the musical projects in the video caught your eye, it might just be the one we’ve featured previously! Continue reading “Give Your Pi Pico Captouch Inputs For All Your Music Needs” →

Thumbs Up To This Pico MIDI Kalimba

March 6, 2024 by Kristina Panos 8 Comments

The kalimba, or thumb piano, is an easy way to make some music even if you have next to no idea what you’re doing. The only real downside is that they are limited to the twinkly sounds of metal tines being plucked by thumbs.

[Jeremy Cook] broke the sonic possibilities wide open by converting a couple of kalimbas into capacitive-touch MIDI instruments using the Raspberry Pi Pico. He started with a small one that is curiously made of solid wood. Usually these instruments are at least partially hollow to allow air to resonate inside the body.

After soldering up all the 1 MΩ resistors necessary to utilize the capacitive touch capabilities of the Pico, [Jeremy] found it a bit difficult to play individual notes on such a small instrument, so he made version two out of a much larger specimen.

This time, [Jeremy] cooked up a custom PCB which he is calling the Pico Touch 2, which adds the necessary resistors at the SMD level for capacitive touch sensing and in turn cleans up the wiring a bit. Be sure to check it out in action after the break.

Okay, so you don’t have an iota of musical talent. You could always build a kalimba that plays itself.

Continue reading “Thumbs Up To This Pico MIDI Kalimba” →

Get To Know Touch With This Dev Board

December 31, 2022 by Jenny List 5 Comments

In the catalogue of the Chinese parts supplier LCSC can be found many parts not available from American or European suppliers, and thus anyone who wants to evaluate them can find themselves at a disadvantage. [Sleepy Pony Labs] had just such a part catch their eye, the Sam&Wing AI08 8 channel capacitive touch controller. How to evaluate a chip with little information? Design a dev board, of course!

The chip tested is part of a family all providing similar functionality, but with a variety of interface options. The part tested has eight touch inputs and a BCD output. Said output is used to feed a 74 series decoder chip and drive some LEDs. The touch pads were designed with reference to a Microchip application note which incidentally makes for fascinating reading on the subject as it covers far more than just simple touch buttons.

Whether or not you’ll need this touch chip is a matter for your own designs, however, what this project demonstrates is that with the ready availability of cheap custom PCBs and unexpected parts it’s not beyond reason to create boards just for evaluation purposes.

Perhaps the subject of a previous Hackaday piece would have found this board useful.

The assembled switch PCB in the palm of its creator's hand

TTP223 Brings Simple Touch Controls To A LED Lamp

October 4, 2022 by Arya Voronova 7 Comments

You can buy small modules with capacitive touch detection ICs — most often it’s the TTP223, a single-button capacitive model with configurable output modes. These are designed to pair with a microcontroller or some simple logic-level input, but [Alain Mauer] wanted was to bring touch control to a simple LED strip. Not to be set deterred, he’s put together a simple TTP223-based switch board.

Initially, he made a prototype using one of the regular TTP223 boards as a module, but then transferred the full schematic onto a single PCB. The final board uses an NPN transistor capable of handling up to 3 amps to do the switching job, and Zener-based regulation to provide 5 V for the TTP223 itself from the 12 V input. [Alain] shares the schematic, as well as BOM together with Gerber files for a 2×3 panel in case you’re interested in adding a few of these handy boards to your parts bin.

The TTP223 is a ubiquitous and quite capable chip – we’ve seen it used for building a mouse with low actuation force buttons, a soft power switch, and even a UV-sensing talisman that’s equal parts miniature electronics and fascinating metalwork.

Continue reading “TTP223 Brings Simple Touch Controls To A LED Lamp” →