Dual Power Supply

Dual Power Supply 78-79xx Series

Here is a very simple dual power supply circuit. With using 3 terminals voltage regulator, it’s the best and simplest choice for non-critical applications. 3 terminals term is for input, ground, and output. The 3 terminals voltage regulator. Here are 78xx & 79xx IC (integrated circuit) series that can provide up to 1A load current.

This voltage regulator IC series had on chip circuitry to prevent damage in over heating or excessive current conditions. If the conditions happened, the chip simply shuts down rather than blowing out. These regulators are inexpensive, easy to use, and they make it practical to design a system with many PCBs in which an unregulated power supply is brought in, and regulation is done locally on each circuit board.

This dual power supply provides a dual polarity linear power supply. It can be built easily for delivering up to 1 ampere with the appropriate choice of a centre tapped transformer and 3-terminal voltage regulator pairs at +/- 5V, +/- 9V, +/- 12V, and so on.

Dual Power Supply Schematic

Dual Power Supply Schematic

The 3-terminal pair of regulators you want: 7805 & 7905, 7809 & 7909, 7812 & 7912, 7815 & 7915or 7818 & 7918. The + and – regulators do not have to be matched: you can for example, use a +5v and -9V pair. However, the positive voltage regulator must be a 78xx regulator, and the negative voltage regulator a 79xx one. The user must choose the pair he needs for his particular application. Find more on dual power supply.

See also: 12V Switching Power Supply