Weak light alarm SCZ07 a circuit diagram

As shown in FIG weak light alarm circuit. The core of the oscillator circuit for the alarm SCZ07. Its input signal by the potentiometer W, control, output signal photoresistor

LDR driven speaker Y, a light emitting diode LED work.When adjusting circuit is first placed in the maximum W position, LDR placed standard illuminance 100 lux, and the circuit can not afford to vibration, speaker Y does not sound. Fine-tune the W, so that the resistance from big to small, when adjusted to a certain value, start-up circuit, the speaker issued a beep. sound, then W slightly recall some of the circuit just stop vibration, the alarm on a good tune.For this circuit, when the light is below standard illuminance (100 lux), the speaker issued a warning beep. sound, while the light emitting diode LED lights to show the light is dim. When light is greater than 100 lux, the alarm does not work, that the speaker does not sound, the light emitting diode does not shine.

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