Dual Power Supply with Soft Power Switch

Dual power supply with soft powerThis 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.Dual power supply PCB

Parts list :
BR1 = bridge rectifier 50V/1A or more
D1, D2 = 1N4002
D3 = zener diode 12V 1W (depending on the voltage of the relay)
D4 = 1N4148
C1, C2 = 1000 uF 40V
C3, C4, C5, C6 = 100 nF MKT
C7, C8 = 10 uF 40V
C9 = 470 uF 40V
C10 = 100 uF 40V
IC1 = 7812
IC2 = 7912
SW1 = 2 switch circuits
T1 = BC547
R1 = 10 K 1 / 4 watt
R2, R3 = 2 * 47 1 * 100 or ohms/5W ohms/10W
REL = 2 relay circuits 12V (10A 250V) (for other voltage - change Zener)
TR1 = 2 * 15V 250 mA
TR2 = amp transformer (eg 2 * 50V 6A)
F1 = 200 mA slow fuse
F2 = 6 A slow fuse (depending on transformer)


Power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.

Tags: Dual power supply power supply with soft power switch Soft power for a large transformer soft power switch

Related Post "Dual Power Supply with Soft Power Switch"

15V 1A Regulated Symmetrical Power Supply
This is the easy built 15V 1A
12V / 3A Regulated Power Supply
Here we provide a powerful 12V /
Bench Power Supply Adjustable 1.25V-15V and Fix 5V
This is bench Power Supply give you
1.2V – 57V Regulated DC Power Supply Circuit
This is the circuit diagram of multi

Comments are closed.