I've seen projects similar to this but the trigger mechanisms didn't seem too reliable. So this project is how to install a pressure switch to make your Altoids tin musical. If you haven't tried soldering before this project should be a good start. It only has four simple solder joints to make.
Step 1: Everything You Need.
For this project you will need
Musical greeting card.
Micro switch (radioshack $1.69)
18 or 20 gauge solid core wire
Spool of Solder
Solder station with helping hands.
Step 2: Disassembly of Card
Open card, lift up the inner fold until card is flat don't worry about the sides ripping.
Remove the circuit with battery and speaker.
Locate metal tab that was used by the card as a switch. Bend tab back and forth till it comes off.
Step 3: Configure the Switch
Cut two pieces of wire each about 2 inches long.
Strip about a quarter of an inch of the wire insulation off each end of the wires.
The pressure switch has three terminals; n/o, n/c and C they stand for Normally Open, Normally Closed and Common.
One wire will always be attached to the Common terminal. The other wire determines how the switch will act. Since I want the music to trigger when the tin is opened I'm going to attach the wire to the n/o (normally open) terminal. That way the circuit is open until the switch is pressed.
Slip the wire through the terminals and make an L shaped bend to hold it in place.
You can test that you have the switch configured correctly by touching the two contacts on the circuit board with each of the wires. The music should start and if you depress the switch it should stop.
If everything checks out remove the battery from the circuit to make it ready for soldering.
Step 4: Solder the Wires
Make sure your soldering iron is clean, let it warm up Caution the Iron will be hot enough to burn you if you're not careful.
'Helping Hands' are useful to hold your work stable while you work.
Use the 'helping hands' to grip the wire to be soldered, hook the terminal over the L shaped bend in the wire.
Placing the tip of the soldering Iron on top of the terminal heat up the side of the wire closest to the iron. Touch a strand of solder to the opposite side of the wire (still on the top) when the joint is hot enough the solder will flow to fill in the gap in the terminal and hold the wire securely. Don't add too much solder to the joint. When it's done the solder joint should be bright and shiny.
Turn the switch over and use the same process to solder the second wire to the switch.
With both wires attached to the switch bend another L shape in the other end of the wire. Using the helping hands hold the L shape flush with the Circuit contact.
Heat the wire up with the soldering Iron and touch the solder to the wire so that it flows and puddles around the wire to hold it securely.
Use the same process to solder the last wire to the circuit board.
Step 5: Final Installation
After the joints have cooled install the battery and test. It should play music the turn off when the switch is depressed.
Empty out your Altoids tin and keep the contents (paper and mints) and place the speaker circuit board and switch in the bottom of the tin.
Using solid core wire enables you to position the switch near the edge of the tin, you want it to be just poking over the edge of the bottom part of the tin so that when the lid is closed the switch gets depressed.
When you open the lid the switch will rise and the ânormally openâ switch will activate the music.
Replace the paper but make sure the switch is still just peaking over the edge. Eat about five of the mints then put the rest back into the tin and make sure the lid closes comfortably and you should be all set ;0)