April Fools Hack - The Singing Keyboard

Posted by Jeremy Gillick on 27 Apr 2006 06:15 pm in Funny & Technical

This year I decided to go all out for April Fools and do something that could be duplicated across multiple computers without permanent damage — and so the singing keyboard hack was born.

Update

If you like this project, please vote for it on instructables.com.

Concept

Take the musical element from a musical greeting card and connect it to the caps lock LED on the user’s keyboard. Each time the victim presses caps lock the music plays (and quite loud too). This is a great sleeping prank…It might be found on the first day, or weeks from implementation. It’s the perfect prank.

Why Caps?

True, most people don’t use caps lock very often, if ever, but unfortunately not many other keys are linked to an LED. Also most keys are only pressed momentarily, which would require a solid-state bounceless switch; which I had trouble getting to work. The num lock LED turns on and off several times during boot time, so that’s out and only leaves the caps lock as a viable solution.

Disclaimer

If you decide to do this prank understand that it could be a career-limiting move if you do it to your boss and/or somebody without a sense of humor. I would also recommend to first experiment with a dummy keyboard that you don’t mind destroying.

I will not be held responsible for your problems. ;o)

Setup

To start you’ll need, of course, several musical greeting cards. Hallmark stores usually have a section dedicated to these cards. You’ll also need these tools and supplies:

Screw drivers (Phillips and a wide slotted)
Needle nose pliers
Soldering iron + solder
Thin wire (22 gauge works well)
NPN transistor
Electrical tape

I went out and bought a CoolHeat soldering for this project due to its great portability. If you get one of these be sure to purchase at least 2 replacement tips as they’re pretty brittle and WILL break during normal use.

Getting Down to Business

1) Getting the music. The first thing you want to do is remove the musical element from the greeting card and cut off the excess paper.

2) Switch work. We now need to replace the metal switch with your transistor. First, let me define the parts of the switch I’ll be talking about. The bendable metal part of the switch I’m calling the metal tab, and thing it connects to, or touches, I’m calling the switch contact area.

Take the transistor and bend the center pin back slightly. Then slide the transistor onto the musical element switch area with the outer pins on top and the center pin on the bottom (see picture below & a better picture with notes here). Now make sure the left pin is resting on top of the switch tab and the right pin on the contact area.

Using your needle nose pliers bend the metal switch tab back over the transistor pin and make sure it holds it tightly. Now solder the other pin to the switch contact area.

3) Lets wire it up. Cut two lengths of wire about 12 - 15 inches long. Solder one to the switch contact area (see black wire in picture above) and other to the center pin of the transistor (picture below).

At this point you’ll want to use some electrical tape to tape down all the transistor pins and protect them from being pulled on.

4) Deconstructing the keyboard. Using your phillips screwdriver remove all the screws from the bottom of your keyboard. FYI: On some keyboards there are screws hiding under the rubber feed. Then use the slotted screwdriver to separate the keyboard halves. Be very careful with this step, as it’s likely to create visible damage.

5) LED setup. Find the LED and locate the positive and negative pins. Fish the wires from the musical element up through the keyboard and to the LED. Solder the wire from the center transistor pin to the positive LED pin and the other wire to the negative pin (the image below is from an ergo keyboard).

6) Finishing up. Now close up the keyboard, screw it back together and tape the musical element to the bottom. You’re done, plug it in and try it out!

Results

Late one night I went into the office and carefully chose 3 keyboards to terrorize and an hour later I was done. The following day the first guy got the music playing right away, since he always uses caps instead of shift. He was baffled for a couple of hours, muting the sound on his computer and still wondering why it was making noise. Eventually he turned over the keyboard to find my note, and got a good laugh out of it. Strangely enough, he didn’t want me to remove it.

The second victim found it sometime after lunch. I wandered by, acting as innocent as I could, and suggesting “Try turning your sound off” then asking “Did you install anything today? Could it be a virus?” She started getting a bit concerned and I couldn’t hold a straight face any longer and ended up giving away my guilt.

The last guy never uses caps, so after waiting 2 weeks for it to happen I coerced him to press the key. He did and we had a good laugh about it.

I still have 5 more units setup and ready to go, I just have to find more victims…

Final Thoughts

This has been a really fun project, and one I plan on doing again. There is, however, one thing I would like to improve: be able to hook up the musical element to any key on the keyboard. Earlier on I tried some simple solid-state bounceless switch circuits and they worked well on the breadboard, but not on the keyboard itself. The complete pathway to and from keyboard button has about 120 ohms of resistance, which seemed a bit too much for the small battery. If anybody comes up with a solution, please post it in the comments section here.