Dual rail Variable DC Power Supply Circuit

 Dual rail Variable DC Power Supply  Circuit

* The circuit can be placed into the existing Variable DC Power Supply metal cabinet.

* Q1 and Q2 must be mounted on heatsinks.

Usually, bolting them to the metal case (through insulating washers etc.) proved effective.

* The full ±15V output can be achieved only if the secondary winding of the supply Transformer used in the Variable DC Power Supply is rated at 48V minimum (center tapped).

* When using this circuit, please set the Current-limit control (P1) of the Variable DC Power Supply to any value comprised in the 50mA - 1A range but not higher.

* The second Op-amp (IC1B) contained in the LM358 chip was not used, but its input pins were tied to the negative supply and the output was left open.

DC Power Supply Dual-rail Variable Part list:

R1 = 4.7K-1/2W
R1 = 4.7K-1/2W
C1 = 100nF-63V
C2 = 220µF-25V
C3 = 220µF-25V
C4 = 100nF-63V
C5 = 100nF-63V
Q1 = BD437
Q2 = BD438
IC1 = LM358