A dual output power supply is a power source that provides two separate Direct Current (DC) or Alternating Current (AC) voltage outputs. Both are usually electrically isolated from the power supply input by a transformer. The outputs may be electrically isolated from each other as well, depending upon the design. It may be an adjustable power supply or it may provide fixed voltages or currents. This type of power source is often used by scientists and technicians in laboratories as well as medical and industrial facilities.
If both outputs of a DC dual output power supply are electrically isolated, they can be wired in series or parallel to increase the available voltage or current. Isolated outputs also allow a dual output power supply to drive separate circuits which must not have a common ground connection. If the outputs are not electrically isolated from each other, they will share a common ground. Such a supply may have only three physical connectors, instead of two output and two ground connectors.
Some dual output supplies provide fixed, regulated voltages and currents. In a DC supply, the polarity may be the same or opposite for the two outputs. It may also be selectable with a switch for each output. An AC supply may allow the frequency to be adjusted, or it may be fixed like the voltage.
The outputs of a variable dual output may be adjusted with controls on the unit itself. This type of supply often includes digital readouts to display the precise voltages and current limits selected. Dual output supplies may also be programmable by other equipment using digital-to-analog converters. These supplies often include analog-to-digital converters as well to monitor the actual supply outputs. Like fixed-output supplies, adjustable supplies may also be regulated using switching or linear technology.
Many applications utilize an adjustable dual output power supply, often building it directly into another piece of equipment. Variable AC supplies that can provide up to a few hundred volts are often used in avionics and certain types of test equipment. The power frequency generated by these units is usually adjustable over a broad range. The outputs may include three-phase power as well. Many laboratories and classrooms use bench-top dual output DC supplies providing up to 30 volts DC (VDC) at currents of a few amperes.
Devices such as mass spectrometers, Geiger tubes and electron multipliers may utilize an adjustable high-voltage dual output power supply to provide up to 8,000 VDC. These supplies generally produce very low currents and are often programmable using a standard serial interface. Some adjustable supplies included in X-ray equipment can produce up to 50,000 VDC.