Transformer for VM124 for 24VDC output


#1

Hi, I need an output voltage of 24VDC from this module to feed a phono preamp and replace its switching wall wart power supply which emits an annoying high pitch whistle (common issue these days I think).
Which secondary voltage/no-load voltage should an appropriate transformer have?
The documentation shows in the table (see attachment) transformer ratings for a maximum output voltage of 15-21VDC only. I’ve tried a type with 2x15V in serial (resulting in approx. 30V) which seems to be a bit too much. Thanks and best regards


#2

Hi,

A 22- 24VAC input should be more then sufficient for 24Vdc output.

Note that at sine wave voltage results in a 1.4 times higher unregulated DC voltage on the input of the regulator.