S-100 power supply transformer

I respectfully disagree. ? In a center-tapped full-wave rectifier circuit the output voltage is half what you get if you use a bridge rectifier. It is not the most efficient circuit in terms of transformer design, because each half of the secondary is used only half the time. Thus the current through the winding during that time is twice what it would be for a true full-wave circuit. Heating in the windings, using Ohm?s law, is I^2R, so you have four times the heating half the time, or twice the average heating of an equivalent full-wave bridge rectifier circuit. You would have to choose a transformer with a current rating 1.4 times as large as compared with the ( better ) bridge circuit; besides costing more, the resulting supply would be bulkier and heavier ?. from the good book ? ? The art of Electronics ? The disadvantage of a bridge is two diode voltage drops. Diodes are a lot cheaper than transformers though. Best regards, Steven ------------------------------------------------------------------------- Hi This is the result of when the current actually flows. It only flows when the voltage is near the peak. This changes the average power dissipated in the secondary winding ( the VA rating ). Altough, the 1.414 is the worst value and the real value is somewhere between 1 and 1.414. It make no difference what type of rectification is used, fullwave bridge or center tap. Watts are watts and there is no way around it. It is true that the load current rating is halved for the secondary turns for the center tapped fullwave rectification but the VA rating of the transformer remains the same. I'm not sure what the book you reference says. I do know how power is calculated and it is always the vectored volts times amps. The current flows out of the transformer when the output voltage is close to the peak. This means that the rms current of the secondary needs to be compensated to account for when the current actually flows. If your transformer has a secondary rated at 10 amps that can only feed a rectifier and capacitor filter of 7.07 amps. That would change if feeding a inductive filter because of when the current flows. If it was a center tapped with two diodes, it would be 14.14 amps instead of 20 amps. Still, the VA rating of the transformer does change. Dwight ---------------------------------------- full