In this tutorial, we are making a 555 timer circuit. This circuit is one of the most useful circuits. Multivibrators and oscillators can be made from discrete components to generate basic square wave output waveforms. But the NE555 IC is designed to produce an accurate output waveform with the addition of a few external components. This IC has been around for ages and is still being used in 100s of electronic projects.
It is called a 555 timer because it has three 5KΩ resistors internally connected. These are used to generate two comparator reference voltages. This IC is a cheap, extremely robust, and stable 8-pin device that has three modes of operation. That is, Monostable, Bistable, Astable Multivibrator. The 555 timer IC is used as a precision timing device that acts as a timer to generate single pulses or long delays. Also as an oscillator produces continuous stable waveforms of duty cycles from 50-100%. The circuit mentioned here is a 10 minutes timer circuit.
Hardware Components
The following components are required to make 555 Timer Circuit
| S.no | Component | Value | Quantity |
|---|---|---|---|
| 1. | Battery | 9V | 1 |
| 2. | IC | NE555 Timer | 1 |
| 3. | Switch | Push button | 1 |
| 4. | LED | General purpose | 2 |
| 5. | Resistor | 10K, 330Ω, 2.2M | 1, 2, 1 |
| 6. | Variable Resistor | 550K | 1 |
| 7. | Capacitor | 10nF, 150µF | 1 |
NE555 IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer
555 Timer Circuit
Working Explanation
The operating voltage of this circuit is 9V. The 555 timer IC is wired as an Astable multivibrator. To set the time duration of this circuit we have used a 550KΩ variable resistor. When this circuit is powered it will initially stay off. On pressing the switch S1, the IC will get the voltage and start its operation. Since we have set the time to 10 minutes therefore the LED will light up after 10 minutes. You can increase the time duration by changing the value of resistors and capacitors connected at pins 6 and 7 of the 555 IC.
Other resistors are used to limit the current going into LEDs.
Applications and Uses
- LED/Lamp flasher circuits
- Alarm circuits
- Delay circuits
- Pulse generations
