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  • Author Author: tariq.ahmad
  • Date Created: Date Created
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Making Music with a Lego Guitar and Capacitive Touch -- Episode-637

In this latest episode of element14 presents, Katie and John embark on the challenge of transforming a Lego guitar into a fully functioning musical instrument. The duo starts by connecting a Raspberry Pi 3A to a robot mini-amplifier, which is then linked to a speaker. The primary challenge is incorporating functional buttons into the guitar without compromising its aesthetics. 

Watch the Video:

 

Downloads and Links | Discussion

Initially, physical buttons were considered, but concerns about protrusion through the strings led them to explore an alternative solution. Katie introduces a Seeed Studio 12-key capacitive touch sensor (MPR121), allowing for touch-sensitive buttons. The team contemplates placing these buttons on the back of the guitar neck, making them invisible from the front while the guitar is in its stand. 

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The capacitive touch solution appears promising, offering a more discreet approach compared to physical buttons. Challenges arise in finding the right material to conceal the wiring. Katie experiments with conductive paint and tape, ultimately opting for copper tape covered with vinyl sheets to achieve a seamless integration.  

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Another critical aspect is the programming of the Raspberry Pi to interpret signals from the capacitive touch sensor. Katie describes a Python program she developed that plays various guitar chords at the push of a button. The Pi is connected to the touch sensor, enabling chords to be triggered from the guitar. 

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The final reveal showcases a Lego guitar that not only looks like the original, but also functions as a musical instrument with touch-sensitive controls. The team discusses the challenges they faced, providing valuable insights into the technical aspects of programming and problem-solving for electronics enthusiasts combining Lego builds with functional components. 

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Links and Downloads:

Bill of Material:

Product Name Quantity Buy Kit
RASPBERRY-PI SBC, Raspberry Pi3 A+, BCM2837B0, ARM Cortex-A53, 512MB RAM, MicroSD, Wifi, HDMI, 1×USB 2.0 1 Buy Now
MULTICOMP PRO MicroSD Card, 32 GB, Raspberry Pi 1 Buy Now
SEEED STUDIO Touch Sensor Board, with Cable, Capacitive, I2C, Arduino & Raspberry Pi Board 1 Buy Now
MULTICOMP MC001814 Tape, General Purpose, Copper Foil, 10 mm x 50 m 1 Buy Now
DFROBOT Evaluation Board, Mini Audio Stereo Amplifier, 3.3 V to 5.5 V Supply, Class D Amplifier 1 Buy Now
VISATON Speaker, Full Range, 2 W, 8 ohm, 150 Hz to 20 kHz 1 Buy Now
PRO SIGNAL 3.5MM JACK PLUG TO BARE ENDS -1M 1 Buy Now
 

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  • in reply to hifromkatie

    You could perhaps make your own electr(on)ic. Buy the neck and bridge but then make the body and customise it - e.g. infinity mirror. Build in an effects unit, add a Bluetooth transmitter, backing track media player etc. 

    You could also have a go at customising the neck with fingering positions that light up in time to a backing track or some sort of training tutor/game. Make learning a lot more interactive and a lot more fun.

  • in reply to hifromkatie

    Looking at the construction of the original neck, you would probably need quite a thick PCB in order to be able to route it to take a normal Lego stud. You might be able to do a double layer, have the Lego stud pattern cut out of the first layer then have a solid second layer which fits flush to the top of the studs on top. However it may be difficult to get that to snap firmly onto the stud as it won't have the subtle injection moulding taper that you get with brick to brick. 

    Alternatively it may be easier to replace the original fret tiles with some plain tiles and then glue the PCB directly onto them instead. 

    image

    Silk screen the fret lines onto the PCB to match the existing pattern and then replace the fret dots with flush-mounted LEDs. You can pocket out the replacement tiles behind if you needed to.

  • in reply to hifromkatie

    "...Thankfully I found someone selling the older (discontinued) version which didn't actually spray, so he still got one..."

    On the downside, it probably means that now you have to modify it to become full functional, so as you can water the lawn with it.  Slight smile

  • in reply to hifromkatie

    Have you seen the Spyker KAT 2X 3D printed tracked platform ? Could be interesting as it can take the weight of an adult as demonstrated here:

    https://youtu.be/CGrJRtJR6D4?t=629

    Spotted it being used for a spot of RC deckchair gardening:

    https://www.youtube.com/watch?v=qfjeXVw3zlU

  • in reply to beacon_dave

    We nearly got my son the bruder sprayer, before reading that you filled it with water and it would actually spray the water through the nozzles. The thought of giving that to a 3 or 4 year old (it was a good 5 or 6 years ago) horrified me, as I was sure we'd end up with very wet carpet!

    Thankfully I found someone selling the older (discontinued) version which didn't actually spray, so he still got one.

    I love the idea of RC toys trending the garden, it ties into an idea I've had for a year or so to make a self driving ride on toy tractor (battery powered one) , just to treat it the theory of retro fitting a DIY self driving mechanism to something. Got as far as getting a price for a tractor last summer, but it's still on the ideas list for now

  • in reply to hifromkatie

    There used to be loads of little electronics projects for electric guitars. The hard part is playing the thing though... Slight smile

  • in reply to hifromkatie

    I think it must be close to the point where some of these RC models could actually start tending your garden for you.

    https://www.youtube.com/watch?v=gewm6uO509c

    That excavator looks like it could dig holes/trenches to plant bulbs with even spacing. Probably more precise than I could manage by a hand trowel. 

    A bit of computer control and you could go from Landscape CAD designs to carefully marked out gardens.

    Probably need to hand remove all the usual buried builder's rubble and dig over but once that is done then these little machines could probably slowly manicure it from then on. Even if it's levelling or top dressing or direct sowing seeds into ploughed furrows.

    If you look at some of the 'driving days' where they have 20 or so of these machines working together over a weekend, it's surprising what they can manage to shift around.

    Lawn care is another possibility - have machine vision to detect and deal with moss/weeds and to overseed the bare patches.

  • in reply to Fred27

    Lego is great for getting kids to engage with things like programming. Actually, I've been in to my kids school this afternoon showing them how to program the Lego Spike prime sets, and they all love it so much.

  • in reply to beacon_dave

    Thats cool, I'll have to check out the bruder conversions, that'd be cool for around the garden in the summer

  • in reply to hifromkatie

    "...Nice, we've gone with the Bruder brand 1:16 scale farm machinery (as the first tractor and trailer were pass on from my cousin), but I bet you could do something similar with those and adding motors..."

    That site does RC conversion chassis for 1:16 Bruder machines as well Slight smile

    Starting with larger scales and Power Functions would likely make life a lot easier.