Intro: Variable Power Supply
Now this is one of the most important thing for any electronic hobbyist. Every project you make requires a power source. And as these supplies tend to be expensive its better to make them using cheap parts. So what I did was I made two power supplies.
The first power supply I made is for voltages lower than 9 V. I made it by using a power adapter for PS2. The adapter is rated at 8.5 V and 5.6 A.
The second power supply was for voltages lower than 15 V. I made it by using a power adapter of my old laptop. The adapter is rated at 15.6 V and 5 A.
So lets begin.
Step 1: Parts Acquisition
For the first circuit using the PS2 adapter of 8.5 V:
1) Electrolytic Capacitor of 10uF (This is for filtering the ripple).
2) Ceramic Capacitor of 100nF.
3) Regulator IC L200.
4) 1.5 K Resistor
5) 5 K or 10 K Potentiometer.
For the second circuit using the laptop adapter of 15.6 V:
1) Ceramic Capacitor of 100 nF (This is for filtering the ripple).
2) Electrolytic Capacitor of 10 uF & 1 uF.
3) Regulator IC LM350.
4) 240 ohms Resistor
5) 5 K or 10 K Potentiometer
6) Diode (This is for discharging the output capacitor).
2) Soldering Iron
3) Solder Wire
4) Heat Sinks for the ICs.
5) Two Conectors,
6) Two Voltmeters.
Step 2: Making the Circuit
Making the circuits is a fairly easy and simple task.
The first thing to do is to peel of the wire from the output end of the adapter. You must also separate the two wires and determine which of them is the positive and which one of them is the negative.
Then connect the wires to the connectors and solder them onto the veroboard. After that make the respective circuit shown in the figure above. The figures with the axis shows the circuit you want to make and their connections.
The final result is shown in the image above. Once done then it is time for testing.
The voltage of the first circuit will max reach 6 volts and can supply up to 5 A. The voltage of the second circuit will reach 14 V and can supply up to 5 A.
Step 3: Making Changes in the Circuit
Now what to do if you don't have the adapters that I have used. Then you should use whichever adapter you have with you. You can then use any one of the circuit you want and just change the power adapter the output voltages will vary accordingly.
Caution! But before you connect the adapter make sure to read the data sheets of all the components to see that they can withstand the power of your adapter. Otherwise your circuit might get overheated and eventually burn up. So be careful at all times. Also make sure while operating that no loose connection should exist.
Proteus Simulation file is included if you want to see your changes before actually making them. This helps a lot.
Waiting for you feedback!