Wake Up Siren
Are you a late sleeper?
Even if you are, don't worry!
Because you can make this alarm siren that wakes you up gradually as the day dawns. First, set the switch to position OFF and complete the wiring.
Then, set the switch to ON to turn on the power. Can you hear the siren sound coming from the speaker?
The siren sounds when you expose the CdS cell to light. When you cast a shadow over the CdS, the siren sound stops. Like the electronic buzzer in Project Operational Amplifier Buzzer, the alarm siren uses a multivibrator, and controls its operation with the CdS.
Turn on the power for this project when you go to bed at night, and sleep with your room dark. Then, the alarm siren will wake you up the next morning.