This is a Simple 0.5V Negative Supply Circuit Diagram . This simple circuit consists of two LEDs and a photo diode. It generates a negative voltage with a current level of a couple milliamps. It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output. Note: This circuits is not particularly efficient. Simple 0.5V Negative Supply Circuit Diagram