1. Practical light control LED night light circuit diagram
Small electronic production suitable for beginners, LED night lights energy conservation, practical, especially suitable for places with elderly people and children in the family.
1. The light resistance is endless, and the bright resistance is about 2K.
2. In addition to the R1, the resistance is 1/4W, and the remaining resistors are selected 1/8W. The diode is a normal stream tube, and IN4001 can be.
3. The working voltage of the white ultra -bright LED is between 2.3 ~ 2.6V, and the current should not exceed 20mA.
4. The two ends of the capacitor C2 are between 1.2 ~ 3.4V.
5. Working principle: Full -wave rectification charges C1, optical resistance controls the triode 9014, and the environment is bright and the BG1 is turned on to short the LED circuit, and the darkness is blocked, so that the LED can withstand the voltage of the C2 and light up. D5 plays a protective role. Total power consumption 0.3W.
2. The principle of light control small night lights
This optical control small night lamp circuit is composed of self -excited multi -resonant oscillator, optical control switch circuit, output circuit and power supply circuit, as shown in the figure
The self -integrated integrated circuit IC, resistor R1, capacitors C1, C2, diode VD1 and potentiometer RPL are composed of time -based integrated circuit IC, resistor R1, capacitor C1, C2, C2, diode VD1, and potentiometer RPL.
The optical control switch circuit consists of an optical resistor RG, potentiometer RP2, resistor R2, R4, and transistor V1, V2.
The output circuit is composed of transistor V3-V5, resistor R3, R6, R7, capacitor C3, diode VD2, and lighting light EL.
The power supply circuit is composed of the antihypertensive capacitor C5, the rectifier diode VD3, VD4, the voltage voltage diode vs and the filter capacitor C4.
After the AC 220V voltage is reduced by C5, VD3 and VD4 rectification, VS voltage voltage and C4 filtering, the L2V DC voltage is generated to provide a self -excited multi -resonant oscillator, optical control switch circuit and output circuit.
After the oscillation of the multi-resonant oscillator, the output oscillating pulse signal from the 3-pin output of the IC. After the signal is enlarged by the V3-V5, it drives EL to glow. Adjusting the resistance of the RPL can change the operating frequency of the self -stimulating multi -resonant, control the output pulse occupation ratio, thereby adjusting the brightness of EL.
In the case of light during the day or at night, the light -sensitive resistor RG is illuminated by light and the resistance value becomes smaller, making VL saturated, V2 cut off, LC loses the working power supply and stops working, EL does not glow.
At night, after the lighting of the interior was turned off, the resistance value of the RG increased to make VL interception. V2 was turned on. Adjusting the resistance of RP2 can change the sensitivity of the optical control switch. Component selection
The RL-R4 and R6 use 1/4W carbon membrane resistor or metal membrane resistor; R5 is 1/2W metal membrane resistor.
RPL uses a linear synthetic membrane potentiometer or organic solid potentiometer; R 叨 uses solid variable resistors. The RG uses MG45-32 optical resistor.
The CL-C3 uses a monologue capacitor; the C4 uses an aluminum electrolytic capacitor with a voltage resistance of 25V.
VDL uses 1N4148 silicon switch diode; VD2-VD4 is selected with LN400L or 1N4007 silicon rectifier diode.
VS uses silicone voltage stabilization diode with LW and L2V.
VL-V4 uses S9014 or 3DGL2 silicon NPN transistors; V5 uses 2SD880 silicon NPN transistors.
IC uses NE555 time -based integrated circuit. EL uses a small light bulb of 6.3V and O.LA.