How to Build a Simple Electronic Timer Circuit From Scratch Using Basic Components

How to Build a Simple Electronic Timer Circuit From Scratch Using Basic Components


Building a simple electronic timer circuit from scratch using basic components is a fun and educational project for beginners in electronics. A timer circuit provides timed control of another circuit by counting time intervals. With just a handful of inexpensive components, you can make a timer that is useful in many applications.

In this article, I will show you how I built a simple adjustable timer circuit using just a few basic components that can be easily obtained.

Components Needed

To build the simple timer circuit, you will need the following components:

That's it for the major components. You will also need connecting wires and an on/off switch.

How a 555 Timer IC Works

The 555 timer is an 8-pin integrated circuit chip that can be used to create pulses and time delays. Here is a quick overview of how it works:

By selecting R and C values, we can set the desired time delay. The output pulse width is approximately 1.1 x R x C.

Circuit Diagram

Here is the schematic diagram for the simple 555 timer circuit:

The 555 timer is wired in monostable mode so it operates as a one-shot timer. Let's go through the key points:

Building the Circuit

I used a solderless breadboard to build the circuit. This makes creating and modifying the prototype easy. Follow these steps to assemble the timer on a breadboard:

  1. Insert the 555 timer chip into the breadboard aligned with the power bus column.

  2. Add the capacitor and resistors in the corresponding rows. Watch the polarity of the electrolytic capacitor.

  3. Connect the transistor, LED, and potentiometer to their points on the diagram.

  4. Run wires from the power bus to VCC and ground pins of the 555. Add the battery connector.

  5. Insert jumper wires point-to-point to complete the connections. Double check your layout.

  6. Finally add the trigger switch between Pin 2 and ground.

Once assembled, verify all connections match the circuit diagram before powering on.

Testing and Using the Timer

To operate the timer circuit:

To adjust the duration, rotate the potentiometer knob. Turning clockwise increases the resistance making a longer delay up to about 15 seconds.

Some ways to use this simple timer in practical applications:


Building the 555 timer circuit only takes a few common electronic components and provides a versatile timing element. With just resistors, capacitor, transistor and 555 IC, you can create adjustable time delays from seconds to minutes. This is a great beginner electronics project to learn how basic circuits work. After assembling the timer on a breadboard, you can transfer it to a permanent PCB for use in your own electronics designs.