technique_valley

A while back someone needed a simple way to generate a negative 0.5v supply from a conventional transformer type AC to DC power supply.  The circuit below uses a couple schottky diodes and a filter capacitor to perform the feat.  The circuit is handy when using “rail to rail” op Amp circuits which get close to zero volts at their output from a single DC supply but can’t quite deliver without a negative supply.  With the aid of the 0.5v supply circuit shown, those devices can produce a true zero output voltage.

This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines.

This is a classic linear power supply which produces a regulated 18v, rated at about 1 Amp.