Dual Power Supply with Soft Power Switch

Published:2013/3/18 21:18:00 Author:Ecco | Keyword: Dual Power Supply , Soft Power Switch | From:SeekIC

This power supply circuit brings together a dual polarity power supply and soft power to a power transformer (to supply a large amplifier for example) on the same board. The regulator circuit is performed by a pair of 79xx and 78XX (XX = 12 to 24), if the current requirement does not exceed 200 mA, the heatsink is not needed here (but available in the printed circuit board). Tthis circuit part provides power to devices such as amplifiers (preamplifier, fans, the protection module etc. …). Soft power for a large transformer is made by taking the series resistance of 100 ohms/10 watt or two resistors 47 ohm / 5 watts in the primary circuit, the resistance is shorted by the relay after ± 1.5 seconds. This avoids a sudden use of the current during power up. A Zener diode can be adjusted to allow the use of various voltage relay.



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