In this thread will become clear how we can use diodes not only to switch current direction, but its uses as sync open close switch.
The diode behaves like an exit door. If you want to go out you can, but you can't get inside. When it is used in a circuit, it function as a witch depending on the direction the electrons want to go and if they want to go.
Let me explain better, a diode conduct if is forward biased, meaning there is positive charge flowing in the direction of the arrow. If the reverse condition occurs it will turn off. As long as its PIV is not reached, since there it burns up.
Knowing this, how can we use it to allow an inductor to generate and than collapse a field?
Well, to generate the field it must be conducting right?
lets say we get a circuit comprising a transformer a diode, a coil and a load.
Assuming it is connected in such a way as that the diode conducts during pulse on of the primary.
Well, during pulse on, as were said the diode conducts and current pass thru the load and coil generating an electromagnetic field and a voltage across it that opposes the secondary voltage, according to the current flowing thru it and its reactance, reducing the effective voltage across the load.
When the pulse is off or its reverted, the secondary will reverse polarity so the diode is reversed biased now so it should open the circuit. The coil that had a current flowing in one direction and that wanted to keep going in that still same direction will fight the secondary to keep the diode conducting... So if the secondary is made to collapse at the same rate or if secondary has more turns than the coil it will keep the diode off.
