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Why no free wheel diode on FET in this circuit?

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boylesg

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Can anyone explain why the designer has not used a free wheel diode on the FET in this circuit?


Even if the FET could withstand the reverse voltage why wouldn't you use a free wheel diode so that the current can flow in both directions through the coil and maximize power?
MOSFETDriver.gif
 

Apparently the designer WANTS a big voltage spike on the primary (and thus, also on the secondary). That's why there's the comment about no output diodes.
 

barry said:
Apparently the designer WANTS a big voltage spike on the primary (and thus, also on the secondary). That's why there's the comment about no output diodes.
Click to expand...

As I understand it, the designer is referring to the output diodes on a tv flyback transformer that he is using as the transformer in the schematic. They have output diodes on the HV secondary and these need to be removed or by passed, which involves grinding away the potting epoxy to expose them.
 

Well then, I guess he's just not worried about the inductive spike. Or he made a mistake.
 

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