Toy electronic cat circuit (4)

Working principle of the circuit : According to the component values ​​in the picture, eight or nine beeps will be heard every 20 minutes.
If you want to make more calls, you can increase C3. If you want to stop for a longer time, you can increase C4.
In addition, when the battery voltage drops, the stopping time will be shortened and the number of beeps will increase. If
there are higher requirements for this, the voltage must be stabilized . The voltage of the electronic cat's meowing part
rises slowly, so the meowing goes from small to loud, just like the "cat" coming from far to near.