Circuit dual power supply with voltage regulator 7812 7912

Circuit dual power supply with voltage regulator 7812 7912 2

Circuit dual power supply with voltage regulator 7812, 7912 for preamplifier, can have another voltage with Cis 7805 and 7905 or 7815 and 7915. A simple linear power supply, composed of 78xx and 79xx, can provide power for applications such as preamplifier stages, headphone amplifiers, and other devices that require positive and negative voltages.

Schematic Circuit dual power supply with voltage regulator 7812 7912


The power supply board structure is basic, consisting of a filter rectifier section and a regulator section. Four 1n4007 diodes form a complete rectifier bridge, two large electrolytic capacitors are responsible for positive and negative voltage filtering, and the 7812/7912 voltage regulators handle voltage regulation (they can be replaced with other integrated voltage regulation circuits). Two small electrolytic capacitors are used to smooth the output, four 100nF ceramic capacitors are used to filter high-frequency interference, and each output has an LED for operation indication.

This power supply board can provide power for pre-amplification stages of amplifiers, headphone amplifiers, DAC I/V conversion, and low-pass filter amplifiers, among others. The integrated voltage regulator chips can be replaced with others with different voltages, such as 7805/7905, 7809/7909, 7815/7915. The rectifier section is designed discretely and can be compatible with various rectifier diodes (such as normal speed rectifiers, fast recovery rectifiers, and Schottky diodes in DO-41 package).

The recommended input voltage is between 12-18V (for linear regulation, a higher voltage may result in increased heat dissipation from the voltage regulator, and the voltage after rectification and filtering should not exceed the maximum input voltage of the regulator). Here is a description of the image (the image is of the first version, the LED is in SMD format, the final version was changed to a 3 mm LED).

Circuit Dual Power Supply With Voltage Regulator 7812 7912

There are many manufacturers of these integrated circuits, so you can find KA7812, MC7812, LM7812, L7812, CW7812, LR7812, AT7812, NCP7812, PJ7812, NCV7812, HX7812, KIA7812, SK7812, 7812, AS7812, WD7812, SC7812, NJM7812, LR7812, SCD7812, HT7812, TCM7812, BA7812, UA7812, ICW7812, UPC7812, UA7812. The prefix depends on the manufacturer, so each one uses their own. You can use any suffix in this assembly or in any maintenance you do. The only difference is that parts from a certain manufacturer may be more reliable than those from another.

List of chips with negative voltage: KA7912, MC7912, LM7912, L7912, CW7912, LR7912, AT7912, NCP7912, PJ7912, NCV7912, HX7912, KIA7912, SK7912, 7912, AS7912, WD7912, SC7912, NJM7912, LR7912, SCD7912, HT7912, TCM7912, BA7912, UA7912, ICW7912, UPC7912, UA7912.

The suffix is important, as it can indicate the type of operation suitable for the chip, as well as the maximum current supported. Some voltage regulators, even in the TO-220 package, can support currents of 500mA, 1A, 1.2A, and 1.5A. So you should pay attention to which one is suitable for your application.

Negative Supply
Positive Supply

Bom Circuit dual power supply with voltage regulator 7812 7912

Name Designator Description Quantity
10k R1,R2 0603 2
220uF/16V C1,C2 Electrolytic capacitor 2
2200uF/35V C3,C4 Electrolytic capacitor 2
100nF C5,C6,C7,C8 Ceramic capacitor 4
VPOS LED1 LED 3 mm 1
VNEG LED2 LED 3 mm 1
LM7812 U1 TO-220-3 — Positive linear voltage regulator 1
LM7912 U2 TO-220-3 — Negative linear voltage regulator 1
HEATSINK-TH_L15.5-W10.5-XSD1226-005 HS1,HS2 15×5×10.5×24 mm heat sink 2
DB301V-5.0-3P CN1,CN2 Kre 3 pin Borne Connector (KF301, KR301) 5.08 mm, 2
1n4007 D1,D2,D3,D4 Diode 4

Download files and notes

3D Pcb

Download files for PCB in Gerber, PNG, SVG, and PDF



License: Public Domain

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About the author blog author. Electronics technician for the technical school of Brasilia - Brazil. Interested in electronics, circuits and technology in general.

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