5V Battery Powered Pocket Sized Variable Power Supply

The power supply presented here is Battery Powered, Variable and pocket Sized. It is portable and fully functional. You not have to now carry AA Sized Cells. I get frustrated when I need AA or AAA sized Batteries. At those times, this power supply is made for. It comes handy when you do not want a heavy duty power supply.

This power Supply unit can be adjusted. You can adjust the output with the help of the DIP switches attached. I have used a sticker paper on a left out portion of PCB for showing output voltage information.

The circuit is extremely simple. This can be beginner's first ever power supply unit. You must know Basics Of Electronics and about resistors as they are the main things.

Step 1: Gather Components

1. LM 7805 Voltage Regulator IC

2. A General Purpose Circuit Board

3. 8 DIP Switches (DIGIKEY)

4. 5 220kohm Resistors(DIGIKEY)

5. 9v battery(DIGIKEY)

6. Battery Snapper(DIGIKEY)

7. Sticker Paper

8. Multi Meter(DIGIKEY)

Step 2: The Circuit

The circuit is built around 7805 Voltage Regulator IC and some 220kohm Resistors. Here first of all the 9v supplied by the battery is converted to 5v with the help of 7805 Voltage Regulator IC. 7805 IC has three pins

1 is Vin

2 is GND

3 is Vout

Voltage input is to be done at pin 1 and output at pin 3. We get 5v as an output from the IC. Now the first 220kohm Resistor will convert 5v to 4v. Then by adding another in series we can get 3.5v and so on. I added till I get 2V. I have used DIP switches to adjust the voltage as per need. Image 2 shows connection on breadboard.

LM7805.pdf
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Step 3: Circuit on Breadboard

For making circuit on breadboard. First of all mount LM 7805 IC on breadboard. then we will add some input wires. red wire for positive input from battery at first pin and black wire for negative at second pin.

Step 4: Still Making

Now from the output pin of 7805 IC attach series of 5 220k Resistors. At the end make a pointer attached to positive terminal of Multi meter and negative terminal to 2nd pin of LM7805. We will do this to get the knowledge about the output voltage.

Step 5: Testing

Now move the wire using as a pointer across all the five resistors to check the output voltage.

Step 6: Circuit on PCB

Assemble the components on PCB as shown in the circuit Diagram. It is better if you leave some space on side to attach a paper for output information. Solder the components perfectly. Bend the 7805 IC so that it fits in the pocket. i have left switch number 7 in circuit due to soldering issue. At 8th pin you can get 5v Supply from LM 7805 IC.