I bet some of you had the same problem. I was working on this circuit on breadboard and I found out I do not have means to power that circuit. Batteries are too expensive for testing one circuit. In the end I was able to build small power supply that solved my problems.

Many times we can build PSU with small amount of elements. That is the story in this case. I upgraded PSU that already have 12 V output to 9 V with help of linear voltage regulator.

I am not hold responsible for any damage done during reproduction.

Step 1: Parts and Materials

Parts:
- PCB
- low voltage connector (male and female)
- 2 pins connector
- cooling element with nut and bolt and with isolating foil (foil is optional)
- piece of black and red wire and two pins
- 7809 voltage regulator
- 470 uF capacitor and 100 nF capacitor
- PSU with output between 12 and 16 V

PSU’s nominal current must be 800 mA at max. If you do not posses such PSU, you will be able to find it on electronic waste center or you can buy it on internet.

Tools:
- clips and pliers
- soldering iron and solder wire

Also for soldering so called third hand is welcoming edition.

Step 2: Schematics

Schematic is made out of just three elements: input capacitor, output capacitor and voltage regulator. Schematic is taken out of 7809’s datasheet.

Step 3: PCB

We can divide making of PCB into next steps:
1st step: Position all elements on PCB. Then mark the size of PCB you will be using and that cut marked piece out. After that, adjust holes that elements can fit in.
2nd step: Solder in all the elements. The way how to be soldered in correctly is shown in picture above.
3rd step: Solder in all connections between elements. We can make connections with pieces of wire or we can solder down connections. Last one requires more skills and it is the one I prefer.
4th step: clip of any remaining pins from elements and check all connections. You do not want short circuit.

When you are finished with making of PCB, you must make your pair of wires with pins on one end. Strip wire at both ends and solder one end and twist the other. Then prepare your pins – clip of pins tips and heads. Pins do not need to be same length. After that, solder pins to the wires.

Step 4: Conclusion

Before using PSU please test output voltage. Do that to see if it is working properly. Measure output voltage using voltmeter (or multimeter set to measure DC voltage).

This PSU is intended for smaller loads. It maximum current is around 500-800 mA (milliamps). So please, pay attention when using it because we can destroy voltage regulator.Also, if you want different voltage (5,6,8 or 12 V), you just need to change 7809 with 78xx that has right output voltage for you.

I wish you lot of success making your circuit with this PSU.