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Automatic night light with one LED | How To Build An Automatic Night Light Circuit

Automatic night light circuit will work fine, we use a phototransistor. The response time of a phototransistor is much less than that.
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Automatic night light with one LED | How To Build An Automatic Night Light Circuit

auto night light on off circuit - Electronic Project


An LDR circuit diagram uses an LDR to detect changes in ambient light levels. It is made up of an LDR, a resistor, or a load, and can be used to turn on or off a load when the ambient light level falls below or rises above a certain threshold. LDR circuit diagrams are easy to build and can be used in a variety of applications, such as automatic night lights and light-sensitive alarm circuit diagrams. By using some basic components I am going to make the LDR circuit diagram components we need for making this circuit.

An automatic USB night light circuit diagram can be built using a BD139 transistor, an LDR, or a 3.3k resistor. The circuit diagram is designed to turn on a light automatically when the ambient light level falls below a certain threshold. This could be a useful feature in situations where you need a night light in a dark room. The BD139 transistor is used in the circuit diagram as a switch that turns on and off the LED light. The LDR, and light-dependent resistor, is used to detect changes in ambient light of the levels. When the ambient light of the level falls below a certain threshold, the resistance of the LDR decreases, allowing current to flow through the transistor, and turning on the LED light.

To be sure that our Automatic night light circuit diagram will work fine, we use a phototransistor. The response time of a phototransistor is much less than that of a photoresistor, so the LED is expected to turn on immediately. So when the daylight is gone, the LED will light. For the circuit diagram to be transportable, a button-type battery is used. This battery is similar to those used in electronic devices such as calculators, watches, etc.

Diagram of The Night Light Circuit Works:

auto night light on off circuit.

Hardware Required for this Project:

You can get the components from any of the sites below:

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Working Principle of Automatic Night Light Circuit Project:

A cheap and simple automatic night light using a few transistors or an NE555 timer is shown here. The circuit diagram will automatically switch on the AC lamp when night falls and the lamp will be automatically switched off after a preset time. The working of this night light circuit diagram is very simple. An LDR is used as the sensor of the here. At day time the resistance of the LDR will be low or so will the voltage drop across it, the transistor of the Q1 will be in the conducting mode. When darkness falls the resistance of LDR increases or so does the voltage across it. This makes the transistor of the Q1 OFF. The base of Q2 is connected to the emitter of Q1 and so Q2 is biased which in turn powers supply the IC1.

NE555 is wired as a monostable multivibrator that is automatically triggered at the power supply ON. This automatic triggering is achieved with the help of the capacitor C2. The output of the IC1 remains high for a time determined by resistor R5 or capacitor C4. When the output of the IC1 goes high transistor Q3 is switched ON which triggers triac T1 or the lamp glows. A 9V battery is included in the circuit in order to power the timer circuit during power supply failures. Resistor R1, diode D1, capacitor C1, or Zener D3 form the power supply section of the circuit. R7 and R8 are current flow-limiting resistors.

A voltage comparator is a bistable circuit diagram (flip-flop) that compares two analog signals at the input and depending on the outcome of the comparison it gives HIGH or LOW output. We could imagine it as a small “multimeter” with a switch. When the measured voltage is higher on the first input pin, the switch is turned on. However, when the voltage is higher on the second input pin, the switch is turned off. In this project, we will use an LM393 voltage comparator. More about it in this tutorial.

During the daytime when there is a light, the LDR has very low resistance, or all voltage coming through R1 drops with the ground. This makes the voltage at the base of the transistor very low or it will not switch ON the transistor. Because the transistor is OFF, the current flow will not flow through the transistor. As a result, the LED will not turn ON.

At night when there is no light, the LDR has high resistance and very little power supply dropped with the ground. This makes the voltage at the base of the transistor high to turn the transistor off ON. Because the transistor is turned, current flows through the transistor. It flows from the positive battery terminal, through R2, the LED, and the transistor down to the negative battery of the terminal. As a result, the LED turns ON. The same circuit diagram can be used for a variety of purposes. Check out the Automatic Street Light Control System using the LDR application. Instead of the LED, bulbs are used using a relay. So, give it a shot, or let me know if you have any questions in the comments section below. I will be happy to assist you!

Frequently Asked Questions

What is the working principle of automatic night light using a NAND gate?

Our project was"Automatic night of the light using the NAND gate". The basic working principle of our circuit diagram is that when the light source is active, night light(LED in our circuit diagram) becomes active & when the light of the source is inactive, night light becomes active. We can use this circuit diagram for various purposes.

What is the purpose of a night light?

Nightlights are typically installed to create a sense of security and to alleviate fears of the dark, especially for children. They also illuminate the general layout of a room without causing the eyestrain created by a standard light that the, helping to prevent tripping down stairs or over objects.

What is the definition of nightlight?

A light that is not bright that could be left on through the night, especially for a child. SMART Vocabulary: related words or phrases. Lighting & light fittings in the home.

Are automatic night lights safe?

Night lights are generally very safe to use as long as you follow the manufacturer's instructions and take a few sensible precautions before or during use.

What are the disadvantages of automatic night lights?

High cost of installation as compared to the conventional street lights. Risk of vandalism or theft. Batteries need to be replaced multiple times in the entire life of the cycle, thus increasing maintenance costs. If there are issues with sensors then it might get lit, and it might remain lit for a long time, thus wasting energy.

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