Diode rating??

Hey there,

I have a quick question. In both this (https://www.richieburnett.co.uk/sstc02.gif) and this (https://www.angelfire.com/electronic/cwillis/fetcoil2.html) circuit, they use a 1n5822 above each MOSFET to eliminate any current going through the body diode when the MOSFET is turned off. But... when it is turned on, virtually all of the current flowing through primary (of the tesla coil) will flow through two of the 1n5822 diodes. How then can these circuits get away with using a 40V diode on a 240V+ circuit?

freeskier89 said:

How then can these circuits get away with using a 40V diode on a 240V+ circuit?

Click to expand...

Because there will never be any reversed voltage higher than a few volts going to such diode. You have missed the purposes of external diodes in parallel.
The current will flow through the external diodes MUR1660CT instead.

Thanks! I totally blew by that it was the reverse voltage that needed the higher rating. For some reason I always thought that the 40V rating was for the forward voltage going through the diode, instead of the reverse. Silly me.