Building a circuit on a breadboard

A breadboard is a device for testing temporary electronics projects. Components used to test a circuit can be reused for other projects. None of the components are damaged.

Almost all people start to learn electronics using breadboard because it is the simplest way of making circuit. The photograph shows a typical small breadboard which is suitable for beginners building simple circuits with one or two ICs (chips).


Connections on Breadboard

Breadboard has many tiny sockets or holes arranged on a 0.1’’ grid. The leads or terminals  of most of the components like resistors, diodes, transistors, etc. can be pushed straight into the holes.

A breadboard has 4 rows of holes at the top and 4 rows at the bottom and there are several columns of holes in the middle.

There are two groups of vertical columns in the middle part, as you see in the picture below it has been separated by a blue rectangular block.

None of the rows and columns are linked to one another.

The holes in rows are linked horizontally and column holes are linked vertically.


Converting a circuit diagram to a breadboard layout is not straight forward because the arrangement of components on breadboard looks quite different from the circuit diagram. When putting parts on breadboard you must concentrate on their connections, not their positions on the circuit diagram.

Building a Circuit on Breadboard(Dark Detector using transistor)

Get following components:

NPN transistor- BC547 or BC147 or BC548

Resistor- 100K


Light emitting diode(LED)

Light dependent resistor(LDR)

Connecting wires- Use single-core plastic-coated wire of 0.6mm diameter (the standard size)-You can use wire that is used for Computer Networking.

6V battery (4 -AA size battery)


  1. Thank you for this. I added an indicator LED to show that the circuit is ON (even when it is in the light). I used a tri-color LED that morphs from Red to Green to Blue every few seconds, very attractive. Like these:

    I connected it across the + and – of the battery. Since my entire circuit is on a switch (the Automatic setting of a Lo-Hi-Auto selector switch) the indicator LED only runs when the flashlight is in Automatic mode.

  2. I seriously need help on ma project…. That is building a dark operating switch… Hv no idea and I greatly require your assistance

  3. Hello,
    Interesting Tutiorial.

    Can you post the same circuit if I am using a 12v dc power supply to light a 12 V led bulb?

    Thanks in advance.

  4. Sir your projects from absolute beginners are very helpful. However, I shall be grateful if you could demonstrate a step to step circuit on breadboard as to how to build a digital clock. The circuit may be very simple as I am absolute beginner.

    • I am going to use this system to lock and ulcnok the door and turn on and off all utilities (like electricity and internet) to my home datacenter that operates a network for my entire street as well as my small business.

  5. super sir pls mail updates to me because i am veerly intereested plssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss sir sir

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