Variable DC Power Supply (1-30 Volts, 5 Amps). LM338K Regulator

This simple DC voltage power supply circuit uses a total of 10 components, including the required A transformed, bridge rectifier, and the on/off switch. The main component that achieves the adjustable output voltage is the LM338K voltage regulator IC (Integrated Circuit), which can range from 1.2-30 Volts DC, with a constant current rating on 5 Amps (Amperes).

Please take caution when building this circuit. Since it operates at mains AC voltages, it may cause harm or death if you touch the wrong wires at the wrong time. The TO3 case of the LM338/K will need to be attached to a heatsink, which is not included in the component count.

The filtering capacitor (smoothing cap) is 14,000uF - which is a decent amount, so the output should be fairly clean. Note that that although this DC power supply is variable, it is not necessarily regulated i.e. the output voltage will fluctuate a bit. So, if you use this power supply with a low quality voltage-controlled radio transmitter, it may exhibit slight frequency drifting.