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LM317 LM337 dual power supply PCB schematic. The circuit will serve as a voltage converter with an input voltage of 35 V to produce an output voltage of 1.25 V to 30 V. The positive voltage is being handled by LM317 IC while the negative voltage is handled by LM337. The circuit can provide an output current of 1 A. During the production of 1 A current, the regulator is dissipating too much heat and without the presence of a heatsink, the regulator may get damaged.
The adjustable symmetrical power supply is suitable to be used in audio amplifiers, microphone amplifiers, op-amp applications, impedance converters and other devices that require regulated positive and negative DC supply, since the output current is 1.5 A.
About the circuit symmetrical adjustable LM317 LM337 dual power supply PCB schematic
The basis for the circuit are the voltage regulators 317 and 337 (any prefix, ex: LM317, Ka317, Lm337, KA337 etc.), the minimum output voltage for these Cis is 1.25 Volts and the maximum is expressed by the formula (R2/R1 + 1) x 1.25, with the trimpot in the position of maximum resistance we have about 27 Volts. These ICs support a maximum current of 1.5 Amperes, if you are going to use them in circuits that need more than 200mA, use heat sinks in both ICs.
The transformer should be a center tapped type with voltage and current according to your needs, and these integrated voltage regulators cannot work with voltage above 35 VDC. The large filter capacitors can be used from 2,200µF to 4,700µF according to your needs.
If you find it interesting, you can replace the trimpots with potentiometers. I don’t recommend Dual potentiometers, as I don’t think they have the same resistance at all points.
Before using the power supply, check what voltage you need in your project and, thanks to a multimeter, adjust both trimpots until you get the voltage you need.
LM317 LM337 pinout datasheet
Schematic Symmetrical Power Supply LM317 LM337 dual power supply
Pcb for Symmetrical Power Supply Using negative and positive Regulator IC’s LM317 and LM337
About LM317 datasheet
The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25 V to 37 V. It requires only two external resistors to set the output voltage. The device features a typical line regulation of 0.01% and typical load regulation of 0.1%. It includes current limiting, thermal overload protection, and safe operating area protection. Overload protection remains functional even if the ADJUST terminal is disconnected.
About LM337 datasheet
The LM137 and LM337-N are adjustable 3-terminal negative voltage regulators capable of supplying –1.5 A or more currents over an output voltage range of –1.25 V to –37 V. It requires only two external resistors to set the output voltage and one output capacitor for frequency compensation. The circuit design has been optimized for excellent regulation and low thermal transients. Further, the LM137 and LM337-N feature internal current limiting, thermal shutdown and safe-area compensation, making it virtually blowout-proof against overloads.
The LM137 and LM337-N are ideal complements to the LM117 and LM317 adjustable positive regulators. The LM137 has a wider operating temperature range than the LM337-N and is also offered in military and space qualified versions.
BOM for mounting the symmetrical power supply with voltage regulator IC
|Resistors 1/4 Watt 5%
|220 – Red, Red, Brown, Gold
|4.7K – Yellow, Violet, Red, Gold
|2.200µF/50 V — Electrolytic Capacitor
|C3, C4, C7,C8
|100nF/100V (104) — Ceramic Capacitor
|10µF/35V — Electrolytic Capacitor
|470µF/50V — Electrolytic Capacitor
|KBP307 or equivalent – Rectifier Bridge
|Red LED 3 mm
|LM317 – Adjustable Positive Voltage Regulator
|LM337 – Adjustable Negative Voltage Regulator
|Connectors and their functions
|Terminal block 2 pin 5.08 mm – Transformer connector.
|Terminal block 2 pin 5.08 mm – Voltage-regulated output connector.
|4.7K (472)or 5K (502)- Multiturn Trimpot 3296W
|RUEF110 – Resettable fuse
|12 to 22 Volt transformer with central tap and current as needed up to max. 1.5A
|Solder, Wires, Circuit box, PCB board, heatsink for the ICs, etc.
Download PDF, PNG, and Postscript files for this assembly: PCB, schematic, component layout, component silkscreen, Gerber
- Datasheet in PDF, of the IC Lm317
- Datasheet in PDF, of the IC LM337
- PDF datahseet of the KBL307 bridge rectifier
- Application Note AN-181 – 3-Terminal Regulator is Adjustable
- AN-178 Applications for an Adjustable IC Power Regulator (Rev. B)
- LM317A-337N-EVM User’s Guide
- Adjustable 3-Terminal Regulator for Low-Cost Battery Charging Systems
- Datasheet em PDF RUEF110