You can find here a very useful automatic on and off relay circuit prototype. This circuit is commonly used for many purposes, such as a headlight for a car or a brake light flasher or flashing an AC lamp, etc. You can link any appliance to the relay and get it on and off continuously as the circuit can continue on and off the 12 volts relay.
The circuit has a well-known NE555 timer IC which, due to its uses in the wide range of electronic circuits, is very popular. In the circuit, IC is connected as an astable multivibrator and the 12-volt relay is extracted from the 2N4401 transistor that acts as a switch. The rate of ON and OFF per second can be changed by setting the 100 K pot.
Hardware Components
The following components are required to make an Automatic ON-OFF Relay Circuit
| S.no | Components | Value | Qty |
|---|---|---|---|
| 1. | Resistors | 4.7K, 1K, 470 ohms | 1,1,1 |
| 2. | Potentiometer | 100K | 1 |
| 3. | Capacitors | 10uF, 0.01uF | 1,1 |
| 4. | LED | – | 1 |
| 5. | Diode | 1N4007 | 1 |
| 6. | IC | NE555 Timer | 1 |
| 7. | Transistor | 2N4401 | 1 |
| 8. | Relay | 12V | 1 |
NE555 IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer
Automatic ON-OFF Relay Circuit
Working Explanation
These ON and OFF relay circuits use in many categories such as LED and lights circuits, and lamp flasher circuits which consist of simple two transistor lamp flasher circuits, The LM3909 is considered to be an LED flasher IC operated only on 1.5 volt DC and gives a bright-high current LED Dark Detecting Circuit a dark detecting circuit which will activate the relay in the circuit when there is no light on the surface of the photoresistor.
Applications and uses
The ON and OFF relay circuit is mainly used for car headlight or brake light flasher or flashing an AC lamp etc.
