摘要：It has created an alarm that uses a light sensor, which is useful for securing aplace of dangerous goods storage, or to safeguard the security of a place ofstorage of valuables from people who are not authorized for such valuables. Theconcept of employment of the tool is received as input LDR light which theninverter by IC 4039, so that when there is light received by the LDR, this alarmwill not work but will work when there is no light received by the LDR. Alertswith light works with the power supply of 9 V DC, using the LDR as a sensor,and other components that are used among others as IC 4039 IC 4039 basedNAND gate, the transistor BC 550 c that serves as an automatic switch toactivate buzzer piezoelectric, which serves as an indicator of the alarm soundwhen the circuit is switched o. key words: sensor light alarm
