well actually as I have two transformers (identical) of two older identical chargers I actually wanted also something to stop them from shorting out as the transistors will act like diodes and replace the resistors alowing a current limitation to preven under any circumstance a short circuit. say one transformer is 0.1 volt higher than the other directly connecting them together will make a big bang but a trasistor on each will do the trick unfortunately it means two rectifiers but never mind at least I can have different arrangments for example 24 volts