A transformer in which part of winding is shared between both primary and secondary circuits.In ordinary transformer two winding are electrically isolated but in- auto transformer two winding are not electrically isolated.In figure step down transformer is shown ,AC and CB represents both primary and secondary winding. V1 is the voltage applied to two winding.
DIFFERENCE BETWEEN RESISTOR POTENTIAL DIVIDER AND AUTO-TRANSFORMER
1)Potential Divider have more losses and hence efficiency compared to auto-transformer is less.
2)In potential divider input voltage should always be greater then output voltage,but in auto-transformer if output voltage of the auto-transformer is less then input voltage,then load current is more then input current.
