Dilshan R Jayakody’s Web Log

This is a high voltage, low current, offline, AC adjustable power supply for electronic/electrical experiments. This power supply is mainly design for switch mode power supply (SMPS) experiments and to drive basic high voltage electrical circuits. Thanks to the isolated step-up transformer this power supply breaks the ground loop and provides shock free – safer high voltage output. This offline (or isolation) feature preventing accidental current from reaching ground through a person's body. This unit generates 50Hz or 60Hz (selectable at runtime) square wave AC output, and it is capable of generating output voltage between 150V – 290V AC (on no-load state). Prototype version of offline high voltage AC power supply As stated above this power supply unit is mainly design for SMPS experiments. This is not work well with liner power supplies because transformers in linear power supplies are get overheating from square wave inputs generated through this unit. This is a hig...

In this project we developed 1.5A, 3V to 27V adjustable power supply unit based on LM723 voltage regulator IC. In this project we add some additional options to standard LM723 PSU circuit (available from National Semiconductors) to improve the safety and performance. When assembling the circuit it is necessary to attach suitable heat sinks to both 2N3055 transistors. Single heat sink for both 2N3055 are also acceptable. According to the initial design R8 must be 0.39ohms (5W), but most of the people say it is bit difficult to get 0.39ohms locally (Sri Lanka) so I change value of R8 to 0.47ohms (5W) and it is available in local market. During the testings and usage this system produce an excellent results for us. Complete circuit diagram of the power supply unit is available to download in here .