Motivation
For the standalone version of my Shakuhachi 2 Synth project I needed a small dual voltage PSU with a wall wart, because I don't want to deal with mains in such a small device. First I used an external transformer Yamaha PA-30 which gives a 2x18V AC and the appropriate PSU for center tapped transformers (link auf 3polPSU) with rectifiers and linear voltage regulators. But the PA-30 is quite big and I only needed some 40mA. So I decided to build a new one to make a dual voltage PSU with DC input from a single supply wall wart. I made a small PCB using the BUF634P as virtual ground device and LM317L/LM337L for regulation. This makes for a versatile PSU with a wide range of input and output voltages. You can adapt it to your voltage needs with changing only some resistors. For my usage I took a single supply 36V DC wall wart and made +/-15V from it with a maximum current of 100mA each rail.
Specs and features
- Input: Select single supply DC wall wart according to your voltage needs
- Output: Voltage depends on only 4 resistors / 100mA each rail DC
- Schematic
- Pictures
- Download docs
Implementation
Schematic
Dual voltage PSU from single DC supply: Schematic
Description:
Nothing special. A classic virtual ground schematic. Just refer to the data sheet of the LM317L/LM337L. Calculate R1/R2 and R3/R4 to your needs. The given values here are for +/-15V. Input is from a DC Wall Wart. Choose the voltage to your needs.
Calibration
- Adjust R1/R2 and R3/R4 to your voltage needs. For values refer to the datasheet for the LM317L/LM337L.
Special parts
- none
