You will learn how to make a 5V Voltage Regulator on a BreadBoard to use in your DIY electronics projects. It will help you get started quickly by converting a regulated, unclean input Power Supply source to a regulated one.

An Empty BreadBoard. It is a standard 840 tie-point BreadBoard with two power rails. Nothing to do here, proceed to Step 2.

Power Rails – Breadboard showing power rails. Note that there are breaks in the inter-connections, so you need to put jumper wires to make your power supply available to all four parts of the Breadboard

Start Prototyping – A standard Breadboard showing internal connections of the power rails with some basic components

(see the arrows)


Voltage Regulator – The Voltage Regulator IC (LM7805) is used to regulate 7V to 15V unregulated power supply to regulated 5V supply for further connecting components like LEDs, Microcontroller, etc. Connect it in the same format, i.e. :

From Left to Right: Pin 1 – Input, then Ground and finally Output at Pin 3


Switch – You need to have control when you want the current to start flowing


Capacitors – They act as storage tanks for charge. So, You don’t have to worry about the noise coming in the supply or getting out.

This also explains the size difference. Fat one is 100µF and the smaller one is 10µF. They also have a voltage rating

written on them which tells the maximum voltage they can handle. One has 25V rating and the other has 15V rating

(Guess which?)

LED – Look at that standing in Elvis Presley style. This gives a visual feedback whether you are getting output or not.

Well, what about that little resistor down there?
Ans – It helps to limit the current going through the LED.

Does the resistor has any special value?
Ans – Well, you need to keep in mind that 330Ω will take you through any project with 5V rails.

Why only 330Ω?
Ans – Ohm’s Law

Diode – They allow the current to flow in one direction only, in the direction of the silver/white band. Thus, it prevents your circuit if you accidentally plug in the power supply reversed! ,i.e., positive to the negative and vice versa.

You will need a 1 Ampere rating diode – 1N4001 – 1N4007 (Any one will work. The only difference between these range of diodes is the maximum reverse Voltage that they can handle.)

Thermistor – A thermistor will protect the circuit from large currents. Typically, if the current is more than 500mA, a Positive Temperature Coefficient (PTC) Thermistor will heat up and its resistance will increase to bring the current flow down to 250mA. Then, after the problem is solved, like the most common case of a ‘short’ between power and ground, it will cool down and start working normally

You can also connect a DC Barrel Power Jack compatible with any common wall adapters (mostly 9V or 12V) to provide input power supply. The Regulated Output can be used from the Screw Terminals and can also be given to the bottom Power Rails.

Qty. Product Code Specifications
1 5V Voltage Regulator IC KA7805 or LM7805 KA7805 from Fairchild Semiconductor
1 9V Battery 9V or 6 x AA cells of 1.5V each
1 Switch On/ Off not Pushbutton
1 Capacitor 100µF / 25V Electrolytic Capacitor
1 Capacitor 10µF / 16V Electrolytic Capacitor
1 LED (Light Emitting Diode) Red/ Green Forward Current = 20mA
1 Resistor 330Ω Color Coding: Orange-Orange-Brown
1 Diode 1N4001 Reverse Protection Diode
1 Thermistor 500mA – PTC Positive Temperature Coefficient (not really needed)
1 Screw Terminals 2-Pin Optional

All the circuit diagrams are 

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