At a glance
- Symmetrical power supply for audio devices
- Voltage defined by 2 pairs of resistors
- Small 5x5cm footprint
- PCB available in our shop
This is a simple symmetrical power supply for devices like preamplifiers, phone stages or similar. The voltage regulator IC can provide up to 1A current, but I recommend to use it for <200mA. The voltage drop on the regulator should be a few volts, then you can use it without additional heat sinks.
Voltage is controlled by 2 pairs of resistors. The following values ensure, that the current flowing through the regulator is at least 5mA.
R1 are the 2 inner resistors, R2 the outer resistors.
| Voltage | R1 | R2 |
|---|---|---|
| 5V | 249R | 750R |
| 9V | 249R | 1.5k |
| 12V | 249R | 2.1k |
| 15V | 249R | 2.67k |
| 18V | 249R | 3.24k |
Maximum diameter for the electrolytic capacitors is 8mm.
The capacitors in front of the voltage regulator must be specified for at least 1.5 x the voltage of the transformer. To be on the safe side, you should use capacitors that are specified for 2 x the transformer output voltage. For the capacitors after the voltage regulators (the 4 capacitors near the ICs on the right side named C13-C16), maximum voltage needs to be at least the output voltage.
