Adjustable Dual Power Supply Circuit using LM317 and LM337

adjustable dual power supply circuit lm317 lm337 4

Power project safely: Symmetrical Power Supply Circuit with Lm317 and Lm337! The symmetrical power supply circuit with Lm317 and Lm337 is an electronic circuit that allows the powering of electronic circuits with positive and negative voltages. It is a versatile and low-cost circuit that can be used to power circuits that require positive and negative voltages. The circuit uses two voltage regulators, the LM317 and LM337, to provide positive and negative voltages, respectively. The circuit is easy to assemble and can be used to power circuits that require positive and negative voltages.

How to assemble a dual power supply circuit with LM317 and LM337.

The assembly of a symmetrical power supply with LM317 and LM337 is a relatively simple circuit. The circuit consists of two voltage regulators, an LM317 and an LM337, connected in parallel to provide a symmetrical output. The circuit also includes a filter capacitor, a voltage adjustment resistor combined with a trim pot or potentiometer to make the voltage adjustable. A precision multi-turn trim pot was used, but a potentiometer can be connected to connectors CN2 and CN3.

Schematic Adjustable Dual Power Supply Circuit Lm317 Lm337
Schematic Adjustable Dual Power Supply Circuit Lm317 Lm337

The integrated circuits must be mounted on heat sinks. The transformer should be 12+12 to 28+28 VAC and at least 1.5A current, although one with lower current can be used, but this will be the maximum current of the power supply.

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The maximum voltage will be about 1.4x the transformer voltage, meaning for 12VAC we will have a maximum of 16.8VDC, for 28VAC we will have 39VDC. We typically use a 24+24 VAC/2A transformer for an adjustable symmetrical power supply from 1.25V to 33VDC.

A voltmeter or voltmeter/ammeter module can also be added to the board for a complete benchtop power supply.

See also:

Suggestion of a printed circuit board for this assembly.

Pcb 1 Adjustable Dual Power Supply Circuit Lm317 Lm337
Pcb 1 Adjustable Dual Power Supply Circuit Lm317 Lm337
Pcb 2 Adjustable Dual Power Supply Circuit Lm317 Lm337
Pcb 2 Adjustable Dual Power Supply Circuit Lm317 Lm337
Pcb 3 Adjustable Dual Power Supply Circuit Lm317 Lm337
Pcb 3 Adjustable Dual Power Supply Circuit Lm317 Lm337

Discover the benefits of using a symmetrical power supply circuit with LM317 and LM337.

A dual power supply circuit with LM317 and LM337 offers several benefits. Firstly, it provides a symmetrical voltage output, which means that the positive and negative voltages are equal. This is useful for applications that require a symmetrical voltage output, such as audio amplifiers.

Additionally, the circuit can provide a continuous current output, which is useful for applications that require a continuous current output. Finally, the circuit can provide a regulated voltage output, which means that the output voltage can be adjusted to meet the needs of the project.

These benefits make the symmetrical power supply circuit with LM317 and LM337 an ideal solution for applications that require a symmetrical voltage output, continuous current, and regulation.

BOM for assembling the symmetrical power supply.

Last updated: 11/06/2023 10:59.

PartValueDescriptionAmount
Resistors 1/4W
R1, R2220Red, red, brown, gold2
R3, R44.7KYellow, violet, red, gold2
Capacitors
C1, C22.200µF a 4.700µF/50VElectrolytic Capacitor2
C3, C4, C7, C8100nFCeramic Capacitor4
C5, C610µF/50VElectrolytic Capacitor2
C9, C10470µF/50vElectrolytic Capacitor2
Semiconductors
B1KBP307Rectifier Bridge1
IC1LM317Adjustable positive voltage regulator.1
IC2LM337Adjustable negative voltage regulator.1
LED1, LED2LED 3 mmLED color of your choice2
Miscellaneous
F1, F2RUEF110Resettable Fuse – PPTC 1.1A 30V 100A IMAX2
P1, P25k (502)3296W Trimpot2
CN2Pot12.54 mm 2-pin connector*1
CN3Pot22.54 mm 2-pin connector*1
J1+V2-way KRE (Kf301, KR301) 5.08 mm terminal block, positive voltage output.1
J2-V2-way KRE (Kf301, KR301) 5.08 mm terminal block connector, negative voltage output.1
J3AC-INKRE 3-Way (Kf301, KR301) 5.08 mm terminal block connector, connect transformer1
Solder, Wires, PCB, Case, Source, Heatsink, etc

* Optional, to connect external potentiometer

Download of files for this assembly, printed circuit board in Gerber, PNG, PDF, and PS:

Download

Mirror

Purchase kit for assembly 

Conclusion

The use of a dual power supply circuit with Lm317 and Lm337 is an effective solution to provide a stable and high-quality power supply. This solution is ideal for applications that require a symmetrical power supply, by offering a stable and high-quality output. In addition, the circuit is relatively simple to assemble and does not require many components. Therefore, it is a viable solution for applications that require a dual power supply.

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