How to make a prank musical caps-lock keyboard

Picture of How to make a prank musical caps-lock keyboard
Kipkay has a number of great DIY videos, but my favourite has got to be the keyboard prank.

The gist of it is to fit a fun music module from those musical greeting cards inside a keyboard and wire it to the caps-lock key to trigger the music each time the key is pressed. Do it on a friend's keyboard, unbeknownst to them, and wait for them to press caps-lock by mistake. Genius!

I'm in the ideal situation because many of my colleagues have the same standard issue Dell keyboard at work, so I took one home, wired the caps-lock key with some cheesy Christmas music and took it back to work ready to put my colleagues in the mood before the holidays. Once one is bored of it, I could simply move the keyboard to someone else!

Here's how to make yours!

- Ingredients:

  • Keyboard with caps-lock LED
  • Musical greeting card
  • NPN transistor
  • Thin wire

- Utensils:

  • Phillips screwdriver
  • Solder iron & solder
  • Electrical tape

(Version francaise)
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Step 1: Choose the right keyboard and take it apart

Picture of Choose the right keyboard and take it apart
Let's start simply:
Here we have a USB Dell keyboard with the caps-lock LED next to the wire connection.
Turn it over, remove the many screws holding it in place and keep them in a safe place for now.
Take the cover off and keep it close by.
The caps-lock LED is likely to be marked as such on the circuit board. It will be easy to locate.

Step 2: Get the musical module

Picture of Get the musical module
Choose a greeting card with a great cheesy music. Christmas being only a few weeks away, I decided to put everyone in the mood early and went for Jingle Bells. Get something that plays the music quickly, because people tend to stop it early as they trigger it by mistake, so don't get something with a slow start. Also get a loud one, something embarrassing (:

Take the module out carefully and look at how the music is triggered.

Here it's a piece of paper preventing the contact from the battery. Classy.

Step 3: Find a space for the module inside the keyboard

Picture of Find a space for the module inside the keyboard
This could be tricky. I fitted mine near the arrow keys but I had to cut some plastic tabs away to make space for it and it just fitted diagonally.

Step 4: Wire the module to the keyboard

Picture of Wire the module to the keyboard
This is the biggy! That a lot of soldering steps, but it only takes a few minutes, don't worry.
Fire up the solder iron.

Cut two lengths of wire (about 15 inch each, preferably one red and one black), strip and tin them.
Cut the musical module switch away, you will replace it with the transistor.

Get the NPN transistor and hold it flat side up, pins away from you. Spread the pins apart.
  • Solder the left pin to the positive contact of the battery.
  • Solder the right pin to the other contact of the switch, leading to the music chip (big black blob).
  • Solder the red wire to the middle pin.
  • Solder the black wire to the same contact as the right pin of the transistor.

Now find the caps-lock LED, look at it carefully and find the negative and positive pins (the circuit board will likely have a + sign to indicate it). Turn the board over and:
  • Solder the other side of the red wire to the positive side of the LED.
  • Solder the other side of the black wire to the negative side of the LED.

Note that I used blue instead of black. As long as you keep your colours consistent you should be fine.

Step 5: Test it and clean up

Picture of Test it and clean up
That's it!

Now you need to test it. Make sure the board on the keyboard is in place properly, plug in the USB cable into your computer, test the keys to make sure it works ok, and... press caps-lock. Can you hear the music?

Yes? Victory! Tidy-up the wires with electrical tape, make sure you can close the keyboard properly and put it all back together. Congratulations, you're done!

No? Here are a few things to check that could have gone wrong:

  • The solder connections could be dry, weak or otherwise dodgy. Check them carefully.
  • The transistor could be the wrong one or the wrong way around, or soldered at the wrong location on the music module.
Ah that's a tough one.
You can use a screw-driver to short the left and right pins of the transistor (not the middle), you should hear the music. If not the problem might be with the music module itself.
You can unsolder the wires from the LED side and touch them to a 1.5V battery (red one to the positive), you should hear the music. If not, then the transistor is probably at fault (is it really an NPN?)

Good luck!

Step 6: The final product

Picture of The final product
The result is completely invisible. The Kipkay video suggests to tape the module to the back of the keyboard, but I think it's worth the effort to fit it inside.

Step 7: How does it work ?

Picture of How does it work ?
Ah, but how does it work?

Here's the schematics.

I've highlighted the new connections and transistor in red.

The transistor replaces the switch on the musical module. A transistor is essentially an on/off switch that turns on when it receives current on the B pin. When you press the caps-lock key, the keyboard tries to light up the LED, which sends a current to the transistor and triggers it like a switch and turns on the music! When caps-lock is pressed again, the keyboard turns off the LED, which stops the current to the transistor, which opens the circuit again and stops the music.


Thanks Kipkay for the original idea.
Check out my blog for my other projects.

Thanks for reading!
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Gypsyman7 years ago
it seems like it would be easier just to program it so when you press the button your computer makes the noise. I have actually seen people do this, seems cheaper and simpler.
agent Gypsyman6 years ago
I'm going to make a program that whenever you push ANY key it plays a different sound. I'm going to put it in my flashdrive, and have it that whenever I plug it in it'll copy it to the startup programs. >:D Maybe people should learn not to leave there comps logged in when they walk off!
iambrad agent6 years ago
send me that program when its finished, if you ever write it.
agent iambrad5 years ago
If you're still interested, I'll write it.
iambrad agent5 years ago
 yeah, im still interested
agent iambrad4 years ago
I never really got around to making it. The main problem is that any program like this that hooks global key input is registered as a key logger in most antiviruses.
Redgerr agent5 years ago
im interested as well, would be really funny to have in your back pocket
If you make it make the caplock say "STOP TROLLIN''
You can still get in if you know how. No i'm not telling here. If you want to know, go read 101 spy gadgets for the evil genuis.
mman15066 years ago
KipKay's 'ible: November 6, 2007 jgillick's 'ible: April 3, 2008 How did he plagiarize from something written 6 months before it was written?
his organial blog post was posted before kipkays instruuctable
it is here and check the time stamp
4 months and some ott......to be relatively exact....
lol, mman got 0wned
read 2nd coomment
lolcat3606 years ago
I would hook it up to the E key.
omg that would be halarious! that would be so annoying and would be a great gift ahahaha... totaly
as would i
most used letter in the english alphabet...good idea....i would prefer shift or space....there also used quite often....
oberpriller7 years ago
Awesome. My only problem is that the Caps Lock LED doesn't light up on the keyboard anymore. I guess all the current is going through the NPN transistor now. Next time I'll see if a resistor in line with the switch is enough to get the current running back through the LED.
llemarie (author)  oberpriller7 years ago
Very true! It's a shame that the LED isn't working, that's the only visible change of the keyboard. If you do try the resistor (which should go between the + connector of the LED and the Base of the transistor), I'd be interested to know if it's enough to fix the problem. The resistor of about 8k should give you 0.1mA through the transistor which is enough to trigger it, and hopefully not stealing too much from the LED.
I can't get my head around resistor colour codes... can someone give me a rough idea of what bands a 0.1mA resistor would have?
My keyboard doesn't even have a LED to light. A little box in the corner says, "CAPS LOCK ON" or "CAPS LOCK OFF" when I hit it.
downs7 years ago
Has anybody every heard of being able to re-record one of the musical greeting card chips? there are recordable ones out there but can the standard, one song chip be re-recorded? anyone? Bueller ?
thegeeke downs6 years ago
Ya, it's possible, but it's extreamly hard and I can't and won't explain it in a thread.
DYLEGO6 years ago
does the caps lock still work?
llemarie (author)  DYLEGO6 years ago
Yes, the caps lock ley works as usual. The musical interlude is a bonus, not a replacement for the uppercase. Lionel.
smashbob6 years ago
great i'ble. imagine the look on the person's face when they press caps lock. it must be hilarious. +1
ekulmeekul7 years ago
do you know what would make this circut perfect? power it from the keyboards 5v supply it would never die. Although you would need a voltage regulator. Great instructable.
fd937 years ago
there is a thing avalible on THinkgeek.com that makes an annoying beeping when activated or a sonic grenade but my friend wont tell me how he did it
punkatsub fd937 years ago
just click the shift button 5 times
locofocos fd937 years ago
The annoyatron or somethin like that? It's a preassembled circuit, battery and everything, that will make a little noise at random intervals. I think the intervals are between 2 and 8 minutes, but I'd have to check. It has a magnet on it to attach it to a metal surface if u want. You might be talking about the sonic grenade. When the pin is pulled, it will make a noise, whose frequency and volume can be changed. It stops when the batteries run out XD or when you put the pin back in.
jgillick7 years ago
Great instructable walk through.

Here's the original post which Kipkay got the instructions from:
jaypee42277 years ago
I've actually made two of these keyboards, and they are in place for tomorrow. One is for my boss, and the other is for a friend's co-worker. I would post pictures, but you can't tell a modification has been made! Thanks for such a great idea. I'll let you know how they go.
llemarie (author)  jaypee42277 years ago
Excellent! Bear in mind that it takes most people a while to press the hilarious key. My co-worker kept me waiting for 2 days before he finally pressed it (: Good luck and have fun.
tom0047 years ago
tiuk7 years ago
This would be awesome to do to somebody who uses caps lock too much (read: at all).
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