This is an idea for a
light detection circuit,We use the 555 timer IC.Usually, we used to produce frequency (astable multivibrator) a lot easier.
The single IC with a a few resistors and capacitors, adjust value them to control the frequency output.Can drive speakers directly, as the buzzer sounds.
Circuit Light Detector 555
The CDs LDR is a resistor to change its value with lighting.When applied at pin 4 (reset pin), if hight voltage this
circuit is work. LDR and R3 together with characterized by a simple voltage comparison circuit.
When the light is very low resistance CDS, the voltage at Pin 4 is high, the circuit is to hear a voice come out.