Paper and Tin Foil Input Device




This guide will show you the how to make a cheap, ugly input device for your computer. In this I am using a monome 40h logic board to send the signals to the computer from an eight by eight grid of buttons, but these plans could easily be modified to make a keyboard-format grid using a donor chip from an old keyboard.

I hadn't ordered any parts to make my custom monome 40h but did have the chip, so impatience was the mother of invention.

If you've ever looked inside of a computer keyboard before (if you haven't, you should- it's very fun) somewhat know the mechanics behind it. The type of keyboard this instructable is based around is the membrane keyboard. Check out the wikipedia article on membrane keyboards for more information on this.

How long: one or two hours most likely, maybe more if you don't want it as ugly as mine

---1 encoder board- i used the monome 40h logic board (has led feedback for each key) but any old chip from an old keyboard would work
---wire- you will notice that in the pictures i used bare wire. this is NOT smart as it makes it very difficult to do anything without the signals getting crossed, but that is all i had.
---page protectors
---tin foil

---paper cutter
---hole puncher

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Step 1: Template and Holes Layer

While not absolutely necessary, a template is great help, especially if you're doing something more complicated than an 8 by 8 grid (like a keyboard). I used a total of three templates but only one is needed for this step. If you need an idea for a template, check the membrane layout inside a keyboard or the simple temple I provided.

Slide the holes template into a page protector and use a hole punch to make an opening at each junction. Most hole punches won't make it past the first row so use a paper cutter to make a line between each row. As long as you don't cut the edges the page protector should stay managable. After you finish all holes you can remove the template (or leave it if you think it could use the thickness).

The point of this layer in a membrane keyboard is to seperate two layers of contacts. When a force pushes down one layer into the hole, a circuit is completed and the chip recognizes the key press.

Step 2: Conductive Layers

While actual membrane keyboards use some sort of conductive traces, this will use tin foil because everybody has it and nobody has conductive paste or whatever that stuff is (although the design could be greatly improved if one actually did have that stuff).

For my design, the paths for each layer were quite simple. If you are attempting to make a keyboard, I wish the best of luck to you if you try to do that with tin foil (just look at the traces in a real keyboard... complex). Anyways, for this layout you need one vertical layer and one horizontal layer. The template helps to get them aligned properly.

Some tips on cutting foil- I found it easiest to cut it with a paper cutter to get them straight and not too wrinkled, but I'm pretty sure this dulls the blade quickly. Decide for yourself what method works best for you. If you decide to use a paper cutter like mine you must cut very slowly or else the foil will tear and bunch up near the blade.

After you have enough strips, tape them as shown in the pictures. I would recommend wrapping them around to the other side and taping because these spots make fairly good contact points.

Step 3: Combine Layers

Although a fairly simple step, this took me a long time because mistakes along the way caused them to layers to not match up (even with templates). Basically, what you want to do is face the foil inward to the holes layer with the foil lines going different directions. Even though I warned myself not to, I accidentily arranged the foil the same direction (don't do it!) and had to fix it. You can see this point one of the pictures.

Step 4: Add Wires

Like I said before, use coated wire. Ignore what I did in the pictures.

Use the exposed contacts to get two sets of wires. This is where you will notice it was somewhat important to wrap around the foil as it makes a good contact point.

While soldering would normally be the expected choice for this kind of contact, we're working on paper so that isn't an option. I just slid the wires under the foil and tape (hadn't planned very far and covered foil there in tape) but you could juse tape the wires to bare foil.

Step 5: Connect and Test

Connect each set of wires to the two sets of inputs on your input device. I connected up a contact or two to the monome logic board and tested it out in 40h_serial.mxb in max/msp and it works! (believe me, by the end I wasn't so sure this would work and was surprised and delighted to find that it worked). If you used a keyboard chip just open up a word processor and if anything happens when you press a button, it works!

Hopefully with some foreknowledge your grid/keyboard won't be as ugly as mine, but even I can cover mine with some better paper or maybe rip apart a button membrane from a keyboard and use those for better tactile feedback.

Although it isn't shown in the images, adding dots where the holes/buttons are can obviously help dramatically.

Thanks for reading and if anyone makes one of these please show me, and even if you don't, please give some helpful feedback!

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    10 Discussions


    9 years ago on Step 1

    I'm going to attempt this, but I was wondering if i used a keyboard would I have to make it with all the keys accounted for, or could I make it with less keys. I'm going to try this out of interest but I'd really like to make something less complicated. I want to make a diy electonic drumkit, and I have a progam that corresponds wav files to certain keys, so what I'd really like to do is have seperate indivual keys for each "drum". If you could help me with planning or some ideas I'd appreciate it.


    9 years ago on Introduction

    I found an instructable today that was kinda poor, about how to make a "pad" out of a keyboard that would signal drum sounds on a computer, it was basically one isolated key. I've been wanting to make a home made digital drumset lately, I looked into piezo for a whil but I don't want to buy a drum module or some expensive piece of technology like that. I didn't read this instructable yet, but it looks like it may be promising, it certainly seems more infromative than the one I tried to use earlier today. I hope to get back to working on my diy drums tomorrow, I'll definitely look over this guide by then. If you can help me out or have some advice to offer I would greatly appreciate it. Thanks for sharing with everybody!


    12 years ago

    Nice, this makes for a good conception idea even if it is ugly.


    12 years ago

    you know what would be cool? if you could use it as a gaming device, think about it! You could even make it work as a crazy joypad. I wish i could program so i would make a game that used it. Or maybe you could use it as a mini dance dance revolution carpet! You know those little finger skate boards? Maybe there could be something similar to use with dance dance like games, you would dance with your fingers. Ok, that's not so different from using a regular controller, but i'm sure this principle could be applied to gaming!

    4 replies

    Reply 12 years ago

    These are great ideas! If one used a keyboard chip, it would be very easy to program it for games with customizable keyboard inputs. As long as the chip use is a different format than your regular keyboard (keyboard plug vs usb) you could use both at once. I think once I get some coated wire I'll make a new one of these that is a little neater and use it for gaming (and cover keyboard chip wiring in an instructable if somebody hasn't already).


    Reply 12 years ago

    cool! If you ever do that drop me a line, i'd love to check it out. Other interesting games to those who wish to explore such possibilities would be Bishi Bashi and Beatmania, both for psx. But if i had the technical skills i would built a controller to play two arcade games called Ichidant-R and More More Plus. Since you can configure the controls in mame, i suppose it wouldn't be impossible to do so. This would enhance playing on the computer immensely, and those games are a blast to play versus friends!


    Reply 12 years ago

    heh, don't sweat the self-promotion. That's a good article which I will probably end up linking to later (or maybe within this) to save time and to inform. I had actually planned at one point to wire up an old typewriter but never got around to it- nice to see that it works!


    12 years ago

    If you have a game system with a fully digital input device (Sega Genesis for example) you can create your own simple game controller with a cheapo controller from Ebay. A racing wheel comes to mind. Just solder some wire to each side of the switch contact, then to another switch, like the ones described above, and arrange the switches however you like.


    12 years ago

    Wow, thats nifty. I wanna make one!