A heavy duty 13.8V regulated power supply is a fine thing to have in the shack, but unless you acquire one secondhand, is an expensive little beastie to buy. This means building one should be considered, not only for the cost savings, but also because you can brag about it on air to your mates. [...]

The following power supply circuit uses LD1084#12 voltage regulator, which can provide up to 5Amps with only 1.3v dropout. Input voltage must be around 15v. It is highly recommended that you follow this value exactly, if the input voltage is more, the regulator temperature will increase more.
Calculation for the filtering capacitor:
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This is a regulated and adjustable power supply which can deliver up to 20A and adjustable voltage between 4 and 30V. It is easy to build and uses LM338 and 741 integrated circuits. VR1 it is used to adjust the output voltage. Use very good heatsinks for LM338 and BD140 transistor. The transformer secondary must [...]