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Light sensitive alarm using LDR

Light sensitive alarm using LDR

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  •  August 21, 2023
  •  Light sensitive alarm using LDR
  •  Posted by Marcel at 5:00 am
  •  No Responses
  •  Alarm Circuits
  •  Tagged with: ldr

This alarm activates when the illumination level changes from almost total darkness to a moderately high illumination level. When this happens the alarm is locked and the alarm signal, be it a light or a sound, remains active.

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Fridge Door Alarm Circuit

Fridge Door Alarm Circuit

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  •  May 7, 2022
  •  Fridge Door Alarm Circuit
  •  Posted by Marcel at 12:16 pm
  •  2 Responses
  •  Alarm Circuits
  •  Tagged with: ldr

Refrigerator door alarm circuit with two 555 timers

This refrigerator door alarm circuit alerts you when the door has been left open. Very important, because the power consumption increases when this happends. It uses the popular 555 timer IC

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Shadow detector alarm circuit with two LDRs

Shadow detector alarm circuit with two LDRs

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  •  August 30, 2020
  •  Shadow detector alarm circuit with two LDRs
  •  Posted by Marcel at 10:08 am
  •  No Responses
  •  Alarm Circuits
  •  Tagged with: ldr, relay

Shadow detector alarm circuit with two LDRs

This circuit detects if there is a difference of lighting between two LDRs, and sends an audible and visual warning. Circuits that use two LDRs are more reliable than those that use only one.

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