Key Chain USB Power Supply (For Bread Board Projects)

Hi everyone ,

In this instructable, i am gonna share with you how i made these simple key chain USB power supplies that gives separate outputs from 1 to 5 V DC.

These can be used for bread board experiments that need low voltage dc supplies.

Step 1: Collect the Raw Materials Needed.

This simple project needs a few things.

1. Copper clad board.
2. Old key chain.
3. AS 1117 voltage regulator (3.3 V).
4. 100 Ohms resistors (SMD).
5. Stacking header pins (male).

Step 2: The Circuit...

We are gonna make two key chain power supplies.

One gives 1 to 5 VDC output and the other gives 5 and 3.3 vDC output.

The first one "circuit 1" is nothing but a voltage divider network connected between the +5 and Gnd terminals of the USB output.The voltage divider is designed using five 100 Ohms resistances in series so that each one can have 1 Volt across it. SO, if we need 2 V, then take output across any two of the series resistors. And so we may take 1,2,3,4 and 5 V DC output.

The second circuit, "circuit 2" gives two voltage outputs, 5 and 3.3 V DC. We use AS 1117 smd 3.3 v voltage regulator in this circuit.

Step 3: Make the Circuit.

1. Cut the two pieces of copper clad board as per the picture and to fit the usb port (in the shape of a pen drive).
2. Draw the layout diagram of the circuits on the board (as per the circuit diagram).
3. Carry out the etching using ferric chloride.

Step 4: Solder the Components.

• Solder the smd components carefully.
• Solder the connectors.

Step 5: We Made It :)

• glue a small piece of pcb at the end to make the thickness enough to fit the usb port.
• drill hole to connect the key chain.
• put everything together.