Homemade light-controlled LED lighting circuit diagram

This is an LED lighting with light control function . It does not work during the day and automatically lights up at night. The lamp uses a total of 42 high-brightness white light-emitting diodes, three of which are connected in series, and then connected in parallel to each other and connected to the power source. It is suitable for lighting stairs, aisles, etc.

The 220V alternating current is subjected to capacitor current limiting, bridge rectification, filtering, and voltage stabilization, and a stable 12V direct current is obtained at both ends A and B. During the day, because the photoresistor RG is exposed to natural light and has a low resistance value, the base potential of the transistor VT is low and is reverse biased. Therefore, VT is cut off, the unidirectional thyristor VS gate is turned off at a low level, and the LED is not Bright. After dark, the photoresistor RG shows a high resistance value due to no light, VT is turned on, the gate of VS is turned on with a positive trigger voltage, and the LED is powered on and emits light. Switch K is a manual control switch. As long as K is closed, the LED can illuminate no matter day or night.

The working principle of the circuit is as shown in the figure.

ck="window.open(this.src)" alt="Click to see larger image" />

Component selection, production and debugging

C1 uses polyester capacitors with a voltage resistance of over 400V, which can be replaced by electric fan capacitors. R1 ~ R4 use 1/2W metal film resistors, and RP uses small variable resistors. The rectifier diodes D1~D4 are selected as 1N4007, and the electrolytic capacitor C2 is selected as a 25V aluminum electrolytic capacitor. RG uses MC45 photoresistor (light resistance is not greater than 5kΩ, dark resistance is not less than 1MΩ). DW uses 1W/12V zener diode, VS uses 1A unidirectional thyristor, and the model is optional. Since the human eye will be dazzled when illuminated by light-emitting diodes, the LED light source needs to be modified to make the light diffusely reflected. The assembled LED lamp is put into a discarded circular ceiling lampshade, and the RG is placed where it is exposed to natural light. It only needs to be somewhere that is out of reach of the moonlight. Connect to 220V AC and slowly adjust RP so that the LED does not light up during the day and lights up at night.