Dual output with Center Tap transformer
I have a transformer with dual input 115 V and dual output 9 V and rating power 1.15 VA.



The most you can get out of this is 1.15 VA.
You can wire the primaries in parallel for 115 V or in series for 230 V.
You can wire the secondaries in parallel for higher current at 9 V.
You can wire the secondaries in series for lower current at 18 V.


Output current will be \$ I_{MAX} = \frac {P_{MAX}}{V} \$.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. 230 V and 115 V primary connection.


  I got no reading from center tap to any other winding.


It's probably a polarising pin to prevent it being inserted the wrong way into a PCB. Other similar transformers would have different pin spacing on primary and secondary for this reason.