ELECTRONIC LAPTOP CAJON

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Introduction: ELECTRONIC LAPTOP CAJON

About: Retired Special Education teacher, Design and Technology teacher, and Educational Consultant for Gifted Programs and Design and Technology. Published author with one novel in print. Mountain Biker. Bad guitar…

A cajón (Pronounced ka-hone) is a box-shaped percussion instrument, played by slapping the front or rear faces (generally thin plywood) with the hands, fingers, or palms. They are usually quite large and the player sits on them like a stool. Some have a wire snare that adds a rattle sound. I wanted to build a smaller, more compact version as a prototype, and for proof- of - concept. I will eventually build a wooden version but this one functions so well, I thought it deserved its own Instructable. 

If you like to slap out the beat on an empty beer case, this one will appeal to you as it is made of cardboard. I decided to add amplification because of its small size and was pleasantly surprised by the sounds it produces plugged into a standard guitar amplifier.


Supplies

Hardware items: I used a medium sized, unused and unassembled pizza box, a pool noodle, some double-sided mounting squares, stick on furniture floor protector feet and a small piece of scrap wood.

Electronic items: Some fine hook- up wire, 2 DPDT ( Double pole double throw) switches, a 6 foot connector cord with 1/8” plugs, (the kind used to connect your phone to other audio devices), a 1/8” to 1/4” audio plug adaptor and 4 piezo transducers. These are available from any electronic supplier. I ordered mine online from:digikey.ca

These are Listed as -BUZZER ELEMENT- It’s the part that makes those beeping sounds from your coffee maker or microwave. For that, however, it requires an oscillator circuit. It works just as well as a mini speaker or microphone, and in this case functions like a guitar pickup to detect drumming sounds. 

Part#- 7BB-20-6L0

Price: $1.18 CDN -cheaper if you buy 10 or more

You will need solder and a soldering iron, a glue gun, drill and drill bits.

Note: The cord, adapter, mounting squares, furniture floor protectors, pool noodle are all from the Dollar Store.

Step 1: Prepare the Box

Assemble the pizza box but don’t close it yet. Cut a 3” hole in the bottom. I used a hole saw but you can trace around a DVD and cut with an x-acto. Cut two pieces of the pool noodle to the height of the box and then cut them longitudinally in half. Hot glue them around the hole at 12, 3, 6, and 9 o’clock. These support the lid and mute the sound. Drill holes for the audio cord and switches in the back side of the box and install the switches. A small block of wood should be hot glued below the audio cord exit hole so the cord can rest on it and be fastened to it later.

Step 2: Wiring

Attach the mounting squares. I measured the half way point between front and back and also half way between the pool noodles and each side for the lid. For the base, I staggered them a bit to avoid oscillation between the piezo transducers. 

Next, I pressed the transducers onto the mounting squares and made all the connections. 


A wiring schematic is provided but it is imperative to connect the transducers in parallel, that is, red to red, and black to black. This is also true of the audio cord. Cut off one end and strip the insulation back a couple of inches. There will be 3 wires, red, white, and black. I checked with an ohmmeter and found that the black was the tip of the plug and the white and red, were the two sleeves. Remember this is a stereo plug and the guitar amp is monaural. Solder the white and red together and you’ll solve that problem and allow it to work with a standard guitar amp. Feed the cord through the hole drilled and hot glue it to the wood block leaving enough of the inner wires to reach one switch. ( Be careful to make your solder connections to the transducers quick to avoid overheating them.)


The audio cable connects to the centre position on both switches. The bottom transducers are connected in parallel to one side of one switch. The top transducers are connected in parallel to the opposite side of the other switch.


This will allow the output to be switched between top only, bottom only, or both at the same time to change the sound. Orient your switches so that it is easy to know what transducers are connected. On mine, both switches up= top, Both switches down= bottom, Left down / Right up= All


Before closing the box, attach the adapter to the plug end of the cord, plug into your amplifier and do a test. Making sure your switches are in the right position, tap each transducer in turn. You should hear a drumming sound. You might want to put some beads of hot glue on the wires to keep them from rattling against the box and producing stray sounds.


If it all works, carefully close the box and start drumming. Experiment with the settings. You’ll be surprised at the effects.


Step 3: Finishing Touches

I installed 4 furniture feet on the bottom and a description of the switch positions. I also glued some wood veneer to the top and front to strengthen the lid as it will take a pounding (pun intended). The decals are just for decoration.

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    7 Comments

    0
    hummie8
    hummie8

    8 weeks ago

    Really nice instructable. I "tried" to build a wooden cajon a few years back, but it never really sounded that good. I may just give this a try. Thanks so much for writing and posting this.

    0
    technologyguy
    technologyguy

    Reply 8 weeks ago

    Thanks for the comment. Please remember, I built this a s a prototype for a future amplified wooden one. You'll get more resonance from the wood. You should use 5mm Baltic birch for the top and bottom if you choose to do so.

    0
    manninrh
    manninrh

    Question 2 months ago on Introduction

    I have looked through your info here and notice that you are using a stereo connection for the cajon and it appears you are plugging it into a Line6 guitar amp. I know it doesn't use a stereo input plug so can you please elaborate on the wiring scheme?
    I would prefer to simply use a mono 1/4" plug at the back and a regular guitar/instrument cable.
    I am also toying with the idea of firming up the whole project with 1/8" plywood (which is a ridiculous price these days) for top and bottom with 1/2" stock for edges. This would make a more durable and portable instrument.. I would appreciate your input.

    Thanks in advance,
    Richard Manningham

    I also notice you are in Canada. What part? ...and I agree with Alex; I'd like to hear the output.

    0
    technologyguy
    technologyguy

    Answer 2 months ago

    You are quite correct about the stereo cable. If you check the wiring diagram and explanation you will see that the tip of the plug-black wire is connected to one side of the transducers. The other wires, the white and red are connected together which treats the plug as a mono as opposed to stereo plug. If you have a mono guitar cable, by all means, use it instead. This is basically a prototype for a future wood cajon so I just used inexpensive stuff. When I build the next one, I will use the same plywood you mention- try to get it in Baltic birch as it has no voids and will produce good sound quality. I will also use a guitar type switch with volume and tone controls. This will solve the switching problem and will allow modulation if accompanying someone on guitar using the same amp. I am in the eastern part of the GTA- Greater Toronto Area.

    0
    manninrh
    manninrh

    Reply 2 months ago

    Thanks for your quick response. I obviously missed some of the detail. I look forward to your "upgraded" version but might try something out in the meantime. We are in Ottawa. Too bad you're not closer. It would be nice to collaborate.,

    0
    Alex Stadler
    Alex Stadler

    2 months ago

    Please upload a video. I'd love to hear it!

    0
    technologyguy
    technologyguy

    Reply 2 months ago

    You'll have to wait for the next edition. This was a prototype. I will build a more solid version using baltic birch plywood with volume and tone control as well as switching. At that point I'll upload a video. This one does sound very good but I'm going to improve on it and make a more permanent unit.