New power supply with 48V phantom power and 24V for relays

I have simple power supply for my preamplifiers (and all other) projects, but the 48V phantom power is missing from this device. This required for micrphone premplifier only, if the source is condenser microphone instead of dynamic microphone. Condenser mic source is useful on studios, for live singing, home amplification the simplest and cheaper dynamic microphones more useful. I searched some good solution, but the circuit which convert 48V from 30V AC is not simple enough. IT is true, one transformer not required with this circuit, but I think small PCB transformer with 48V (or 2x24V) is good and cheap solution. This is the reason why 2 transformers inserted to my design. The another thing with this new power supply, that I like relays to switch something if required, therefore I made one more output for 24V for relays (for example switching audio input, or switching speaker protection).

In current design the AC input is for 230V, because the PCB transformers soldered to the board. I like LM317/337 pair of adjustable regulator, the result is much better for me like 78xx/79xx circuits. The output voltage depend on the zener diode connected to the adjust of regulators. All regulators placed to the edge of board, if heatsink required.

The simple schematic:


The PCB:


If 24V for relays not required:


The original PCB for +/- 15V only without transformers:

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 Power supply for preamplifiers 168x89 150 No Yes Yes - - No 22 32 Ask How to order? Please read the rules carefully!