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Old 3rd January 2004, 12:59 PM   #1
MaXiZ is offline MaXiZ  Italy
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Default Small SMPS problem

Hi to all i've just build another SMPS for my power amp project but i'venoticed that che voltage goes up slowly at the output after the caps and the current take from the circuit is very low.. why? maybe a low frequency set? Or maybe a transformer problem?
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Old 3rd January 2004, 02:23 PM   #2
subwo1 is offline subwo1  United States
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One reason could be that you have too many turns n the primary.
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Old 3rd January 2004, 06:31 PM   #3
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i've build just 4 turns...
Turn of 4 wire of 0.5mm of diameter
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Old 3rd January 2004, 07:21 PM   #4
subwo1 is offline subwo1  United States
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Another possibility would be if the pulse width is not getting close enough to 50% at full power output.
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Old 4th January 2004, 08:44 AM   #5
MaXiZ is offline MaXiZ  Italy
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and how can i solve it?
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Old 4th January 2004, 10:24 AM   #6
MaXiZ is offline MaXiZ  Italy
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mybe becouse i've used a 56ohm/4watt resistor instead of 56ohm/2watt resistor?
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Old 4th January 2004, 10:42 AM   #7
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Connect a Resistor of 10K at the output of each gate driver to ground and connect 5.6K resistors at the both outputs of modulator to +12V
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Old 4th January 2004, 10:53 AM   #8
ddog is offline ddog  Finland
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I can't be that you have used 4Watt resistors instead of 2Watt, power rating doesn't matter exept when you have too small power handling, then you will end up with lots of smoke
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Old 4th January 2004, 11:11 AM   #9
MaXiZ is offline MaXiZ  Italy
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Quote:
then you will end up with lots of smoke
???
Quote:
Connect a Resistor of 10K at the output of each gate driver to ground and connect 5.6K resistors at the both outputs of modulator to +12V
What's it's purpose?
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Old 4th January 2004, 11:26 AM   #10
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Resistor at gate act as ground balancing and resistors at outputs act as collector load reference
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