In each workshop you must have a source that is able to provide each current and voltage in a quite acceptable range of possibilities. This variable power supply device goes beyond the conventional power supply source (which rarely exceed 24V output) gives the maximum 57V with 1.5A current.
Voltage of 220V to the transformer via the power switch with built-in fluorescent light. Output voltage of 40V transformer has a improved and filtered after reaching approx. 57V. 100nF capacitors improve the performance of the source against the ripple. LM317 chip in a high voltage is responsible for regulating the output voltage through the resistor divider formed by resistor 220 ohm and potentiometer adjustments (which must be multi-turn). 10μF capacitor in the regulatory lines prevents fluctuations of regulation while the 1N5404 diode prevents the capacitor discharge that can damage integrated circuits. Two output capacitors are responsible for adequately filter the resulting voltage.
The LM317 integrated circuits has internal protection against short circuits, it has cut over temperature. By shorting out the integrated temperature rises quickly and protecting by disconnecting the output jumps up to the termination of a short circuit.
The heat sink must be of multi fins 10 x 5 cm as shown in the picture below. Note that the casing must be insulated with mica.
The rectifier bridge may be of metal. If it is recommended to fix the heat sink. Otherwise, you can be assembled with four 1N5404 diodes as which can be mounted on the PCB, but separated from it to avoid overheating.