i keep blowing fets

Discussion in 'General Electronics Chat' started by lokeycmos, Mar 7, 2011.

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  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    ok, i read the rules before posting this. im not clear if this goes against rule 2. if it is kindly let me know. im experienced with this and know what can happen.i have built many flyback drivers.

    this is a mains powered flyback driver. im in the states so i made a couple changes. im substituting a 1 ohm 10 watt for the 5 ohm 10watt in the power supply. im using half the turns on the flyback primary. i also added an RC snubber across the transformer(5ohm 5watt and 10pf cap). ive been through 2 pairs of mosfets, they keep burning up and shorting. this causes the ic to fail and also burns up the power resistor on the supply. the last pair were 500v 14 amp fets. these also failed.

    im really hoping someone can offer some ideas or suggestions to get this going. ive been working on this on and off for several weeks. Thank you!!
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Wow, that is about as dangerous as anything we've seen. Tying the 15 volt ground to the AC rectifier eliminates the galvanic isolation of the transformer. There are lethal voltages everywhere.

    This is entirely too lethal to discuss.
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