Did you ever see the lights in the house of someone which can lit automatically? You can call it "Dark Activated Lamp". Yes, it is very possible if you know a little about electronics. The necessary components to make this auto lights aren't too complicated. 

You will be calm when encountered outside your house and forgot to turn on the lights of the terrace. Some people are afraid to let his house empty without any light because it is so prone to theft. Those who pass the house can also acknowledge that the owner of the house was not there at home so the lights are not turned on.

Relax, you only need to create a circuit as photos below.

Dark Activated Lamp Schematic

The value of each component is not need too critical and accurate. We can buy it at the nearest electronic store or via online. From a schematic diagram, we can figure out how the circuit work. As for the three resistors, R1, R2 and R3 form a voltage divider circuit to provide a small signal to the base of the transistor to saturated. You can use any small NPN transistor for Q1. D1 is a safety diode to prevent the transistor get damaged, because the relay will generate an inductive voltage spike after the transistor saturated.
Dark Activated Lamp layout

List of Components 

  • R1 = LDR or Photo Resistor
  • R2 = 50k Potentiometer
  • R3 = 1k Resistor
  • D1 = 1N4001-1N4007
  • Q1 = 2N2222 or BC547
  • Relay depends on the power supply that we used. If you use 5V power supply, any relay with 5V to 6V could be used.
You connect the load e.g. a lamp to the relay pins. We can put up LDR outside the box to find out and regulate the intensity of the blackness in your place to activate the relay. 

To be able to set the time of its life lamp , sliding the R2 pot corresponds to the approximate time that you want. You must ensure power rating that can be handled by the relay if the equipment that you will plug from the AC mains supply is switched on. X3 and X2 is the wago connector for attaching the load /lamps.
Don't forget to see mosquito repeller schematic.

Thanks for coming here.

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