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Old 06-06-2009, 01:45 PM   #107 (permalink)
jyanof
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Quote:
Originally Posted by arnolde View Post
jyanof: You might want to try reducing the 10k pullup resistor on pin 7 of the NE555 to 2.2k or 1k, that will increase the current that acts on the MOSFET gate and shorten the switchon phase. That should reduce some switching loss, then maybe you can increase the frequency again somewhat.

The lower your freq is, the more your caps and coil get stressed. (=you really need bigger ones at 20khz)
arnolde, I was using the NE555 to provide a signal for the mosfet driver. The driver and gate resistor took care of the rise and fall times of the mosfet.

i agree that the components are undersized at the lower frequency. If i can, I'm gonna shoot for higher frequency operation.
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