Original source from : http://www.aaroncake.net/circuits/supply.htm
When working with electronics, you always need one basic thing; power. This power supply is great for powering all kinds of electronic projects. It produces a well filtered, variable 1.2-30 volts at 5 amps. It is easy to build and the parts are realitively easy to find.
| Part | Total Qty. | Description | Substitutions |
| C1 | 1 | 14000uF or 10000uf 40 VDC Electrolytic Capacitor | |
| C2 | 1 | 100uF 50Vdc Electrolytic Capacitor | |
| C3 | 1 | 0.1uF Disc Capacitor | |
| C4 | 1 | 0.01uF Disc Capacitor | |
| R1 | 1 | 5K Pot | |
| R2 | 1 | 240 Ohm 1/4 W Resistor | |
| U1 | 1 | LM338K 1.2 to 30 Volt 5 Amp Regulator | |
| BR1 | 1 | 10 Amp 50 PIV Bridge Rectifier | |
| T1 | 1 | 24 V 5 Amp Transformer | |
| S1 | 1 | SPST Toggle Switch | |
| MISC | 1 | Wire, Line Cord, Case, Binding Posts (for output) |
1. The regulator comes in a TO-3 case and MUST be used with a LARGE heatsink. You may want to mount a small fan to blow air across the regulator (I did).
2. The filter capacitor is large. It won't fit on any board so bolt it to the case.
3. You can, of course, add a volt and amp meter.
4. Since this project operates from 120 VAC, you must include a fuse and build the project in a case.