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How to Create a Negative Voltage

Electronic circuits typically have a main voltage supply line, or bus, and a return line, or ground, to complete the circuit. Various components are connected to these points. In most cases, the hot, or live, supply line has a positive polarity, and the ground, or common, point is negative. Some circuits, however, require a negative voltage with respect to the common reference point. In that case, the power supply voltage that supplies the circuit is reversed, with the hot voltage line having a negative polarity, and the common point connected to the positive output of the supply.

Things You'll Need

Power supply source

Instructions

- 1
  Connect the positive terminal of the power supply to the circuit's common or return point. If your power supply is a simple battery, connect the negative terminal of the battery to the circuit's common point.
- 2
  Connect the negative terminal of the power supply to the line or bus point that feeds the hot voltage to the circuit. In the case of a battery, this would be the negative terminal on the battery.
- 3
  Measure voltages in the circuit by placing the positive meter lead on the common feed and the negative lead on the point in the circuit where you want to read the voltage. Note that the meter will show the voltage as positive, but you will know that it is actually negative. The common feed is the reference point against which all voltage readings are taken.

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