This valentines we made this wooden Harp and used Laser and Light Dependent Resistors (LDR's) to play music. I will not be showing you how to make the wooden structure, but you can find the images with exact dimensions if you want to use them. I have used the code of Piano Stairs which I found in this instructable
Here is the list of items that you will require
1. Wooden structure of the harp
2. 12 - 3mm red/green laser dots
3. 5V power supply for the Laser
4. A Tah board (you can use any Arduino as well)
5. 12 - LDR and 12 -1K Resistors
6. A Raspberry Pi
7. Set of speakers
8. Play Dough (yay!!!)
9. Tools - soldering gun, scissors, wires, Tape, Glue gun, and prototyping circuit board.
Step 1: Now Go Make Your Harp
Use can use the above drawing to create your own harp
Step 2: Getting the Circuits Ready
To understand how LDRs work follow this Adafruit tutorial. Connect 6 LDR's with a 1K pull down resistor to one Tah board and 6 1K resistors to another Tah. On one side use the connector from the 5V adaptor to power up the lasers. Connect the lasers in series and stick them using play dough in the upper cavity in the harp.
Step 3: Align Lasers and Place LDRs
Along the slit in the central cavity align the lasers and place the LDR's appropriately. Use the 6 analog pins of the Tah as the input from the LDR's
The following sketch can be uploaded to the Tah boards and you are good to go here.
Step 4: Setup the Raspberry Pi
Clone this repo in the home directory of your raspberry pi.
Next lets make the launcher.sh file run on when the Raspberry Pi reboots. To do that lets change the permissions
on the launcher.sh
chmod 755 launcher.sh
Now test it, by typing in:
This should run your Python code. Add logs directory
cd mkdir logs
sudo crontab -e
add the following line to the end of the file
@reboot sh /home/pi/harp/launcher.sh >/home/pi/logs/cronlog 2>&1
Then restart the Rabpberry Pi