SOWTER AUDIO TRANSFORMERS
75 YEARS OF AUDIO TRANSFORMERS
The voltage and current ratings for the HT winding can be calculated from the dc voltage and current using the formula below appropriate to your rectifier and smoothing circuit. The power rating for determining the size of the transformer is shown below as Pac (Watts).
The formulae below allowances for the voltage difference due to the wave form factor. The voltage drop across the diodes and the resistance of the choke must be allowed for. We specify the Vac on full load so you do not need to allow for resistance of the transformer windings

CAPACITOR INPUT FILTER FULL WAVE Full wave rectifier

FULL WAVE

Vac = Vdc x 1.41

Iac = Idc

Pac = Pdc x 1.41


CAPACITOR INPUT FILTER BRIDGE bridge rectifier

BRIDGE

Vac = Vdc x 0.71

Iac = Idc x 1.61

Pac = Pdc x 1.14


CHOKE INPUT FILTER(Special choke must be used) FULL WAVE Choke input filter full wave

FULL WAVE

Vac = Vdc x 2.22

Iac = Idc x 0.65

Pac = Pdc x 1.44


CHOKE INPUT FILTER(Special choke must be used) BRIDGE Choke input filter gridge rectifier

BRIDGE

Vac = Vdc x 1.11

Iac = Idc x 1.06

Pac = Pdc x 1.18