75 YEARS OF AUDIO TRANSFORMERS
How to calculate your mains transformer ht voltage
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
Vac = Vdc x 1.41
Iac = Idc
Pac = Pdc x 1.41
CAPACITOR INPUT FILTER BRIDGE
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
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
BRIDGE
Vac = Vdc x 1.11
Iac = Idc x 1.06
Pac = Pdc x 1.18