4800

This compact dual power supply is intended for general use on an electronic workbench. It has few distinguishing features apart from being easy to make, compact and is constructed from readily available SMD components. The circuit design is taken from manufacturer’s application notes with minor embellishments. It has been designed to have outputs of 0 to +/- 15 volts (dual tracking) with a nominal output current of 250mA.

As you can see from the circuit diagram, 'Dual Variable PSU.pdf', it is simple and based upon two adjustable linear voltage regulators, an LM317 and the negative LM337 regulator both adjusted via a dual potentiometer. The circuit features a smattering of protection diodes to guard against transients. It also has biasing circuits which minimise the effect of the 1.25V control voltage required by the regulator chips. Normally, circuits of this type would not achieve a zero-output voltage but, using the forward volt drop of two diodes in both the positive and negative adjustment circuits, this problem is mainly overcome.
In addition to the circuit diagram, I have produced a detailed BOM, PCB design and all of the Gerber files required to order the components and build this circuit. To simplify the final assembly, and to produce a compact design, the Potentiometer and power output sockets have been employed to mount the PCB  on the front panel. Please see the full description in 'Dual Bench Power Supply.pdf'' in the 'OTHER' Section.