Feed this piggybank with a coin and it will thank you with a nice burp. The heart of this project is PIC12F683 microcontroller (by Microchip). Sound data is stored in its 2K flash program memory. Sound data bytes are read from memory and are shifted left 8 times to one output pin at 23uS intervals. A simple RC lowpass filter reconstructs the original audio signal.
Step 1: Watch the Video
Step 2: The Piggybank
I built this project in a whey protein (1 Kg) container.PC board, speaker and coin-sensing switch are mounted on the lid.
Step 3: Schematic
Step 4: Circuit Operation Details
Step 5: PC Board Download Link
Download link for PCB, HEX code ASM code & pig eyes-nose-ears (sticker PDF)
Step 6: Coin Actuated Switch
Switch is made with copper /aluminum /tin foil.
Step 7: Switch Mounting
Step 8: Lid
Battery(3 AAA or 3AA cells) are lodged in a separate plastic box