2.5-30V Variable Power Supply Circuit

The variable power supply circuit presented in this schematic allow to supply a consumer with a 60-70 W power consumption and a range of voltage between 2.5-30V with a current from 0.6A to 2.5 A .This variable power supply has a shortcircuit protection and a scale indication for output voltages and current.
The capacitor filter for input voltage must have a value between 3300-6800uF.
Error amplifier of the source it's made with a 741 operational amplifier which is supply with a 40 V tension from D7 , D8 diode.
The reference voltage it's given from an other 741 amplifier which give a very stable reference voltage.
Ic U1 commands a darlington connection made by T5 and T3 which command the power transistors 2n3055.
The limit current is given by T6 trough Pot2 which allow to chance the limit current.
When the current it's over the limit the lamp is lighting.

The 2N3055 transistors must be mounted on a heatsink with a 400cm 2 area.
The transformer must give 30 volts and 3 Ampers.
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