Dual Polarity Power Supply 78-79xx Series
This power supply is very simple dual power supply. With using 3 terminals voltage regulator, it’s best and simplest choice for non-critical applications. 3 terminals term is for input, ground, and output. The 3 terminals volatageregulator here are 78xx & 79xx IC (integrated circuit) series that can provide up to 1A load current.
This voltage regulator IC series have onchip 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 Linear Power Supply provides a dual polarity power supply. It can be build easily for delivering up to 1 ampere with the appropriate choice of centre tapped transformer and 3-terminal voltageregulator pairs at +/- 5V, +/- 9V, +/- 12V, and so on.
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.
Read more: http://www.electronics-project-design.com/DualPowerSupply.html
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