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| Schematic/Diagram |
Automatic night light using LDR and 555 Timer
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| Copyright: |
Electromics Area
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| Description: |
This circuit detects when the day light is gone and activates one or more lights throught a relay
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2063
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| Added on: |
December 01 2008
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| Posted by: |
admin
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| Comments: |
1 Comment(s) | Rate this Diagram | Report bad link |
By admin
December 01 2008
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The LDR (Light Dependent Resistor) changes its resistance depending on the amount of light it receives. The more light it receives the less its resistance value.
A potentiometer is connected in series with the LDR in order to adjust the necessary level of light, that is going to activate the circuit.
This LDR value variation causes a voltage change on the number 2 pin (trigger) of the 555 IC. When this voltage level is less than 1/3 Vcc the number 3 pin (output) goes up.
The amount of time the light or lights will be turned on (number 3 pin (output) is on high level) depends on the 10K resistor and the 220 nF capacitor connected to the 555 timer.
The 555 timer works in a monostable configuration.
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Phototransistor
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Relay
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Electric current
Alternating current (AC)
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Automatic night light using LDR and 555 Timer
