LM723 Power Electronics Workhorse

This is another versatile and flexible chip. I could design current sources, voltage to current transmitters, level translation and many more. You can think of applications beyond the Power Electronics Scope with this. Input voltage up to 40V, Output voltage adjustable from 2 to 37V, Output current to 150mA without external pass transistor and Adjustable current limiting.

“The circuit provides internal current limiting. When the output current exceeds 150mA an external NPN or PNP pass element may be used. Provisions are made for adjustable current limiting and remote shutdown.”

The LM723/LM723C is also useful in a wide range of other applications such as a shunt regulator, a current regulator or a temperature controller

high—quality / high—amperage 28 volt DC power supply.

The design here will be based around the high-current 28 VDC power supply project which has been in the ARRL Handbook for Radio Amateurs for last ten years or so. The handbook article should be studied thoroughly before beginning this project. Most of the power supply’s components can be tracked down at hamfests or salvaged from old or dead computer power supplies.

Improvements to the original schematic from the ARAL Handbook article are the addition of several protection diodes and RF bypass capacitors to the main LM723 voltage regulator circuit. The protection diodes help to prevent reverse base-emitter breakdowns in any transistors if a residual voltage were to leak “backwards” into the regulator circuit.

The RF bypass capacitors will help to maintain voltage regulation even in the presence of high-intensity electromagnetic fields. An optional SCR overvoltage protection circuit will also help to protect any equipment connected to this power supply. The output from the LM723 will control several 2N3055 “pass” transistors which are used to increase the current capability of the power supply.