NAND gate tone generator
When you finish the wiring turn power ON.
You'll hear a tone produced by the multivibrator. Try changing the value of the capacitors from 0.01 µF to 0.047µF.
What effect does this have on the sound you hear?
Try some sort of arrangement so you can switch different value capacitors in and out of this circuit to vary the tone. You might also want to try different capacitors in this project (don't try using any of the electrolytic capacitors, however).
Can you think of any way to use this circuit with any other digital circuits?