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Class D Switching Power Amplifiers and Power D/A conversion |
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#1 |
diyAudio Member
Join Date: Dec 2010
Location: INDIA
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i tried some of the design posted in this forum but aint make no good.....ended up with burning a huge stock of mosfets with no succes....signals are shown on the gate point before connecting mosfets and they disppear after connecting them.....and if worked then it would be for a while....can any one suggest in a simple manner why the hell this happens...
warm regards |
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#2 |
Account disabled at member's request
Join Date: May 2012
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they tend to oscillate easily. You need to keep very short lead lengths. Have decoupling cap at the fet - not at the power supply. And a gate resistor of a few hundrd Ohms close to the gate lead. These are the typical things to do to prevent oscillations which destroy the fet. if you have a 100Mhz scope, you could see possible oscillation at full power happen.
Other common problem is misidentifying the leads - which is gate, drain and source. double - triple check. |
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#3 | |
diyAudio Member
Join Date: Dec 2010
Location: INDIA
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Quote:
how exactly do u say to place those resistor and capacitors |
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#4 |
diyAudio Member
Join Date: Jul 2008
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Are you sure they are genuine parts?
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#5 |
diyAudio Member
Join Date: Dec 2010
Location: INDIA
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#6 |
diyAudio Member
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
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An interesting point when playing fet's, is NEVER, NEVER, NEVER let the gate pin floating
![]() ![]() This sometime happens in SMPS manipulated by unexperienced people. Good luck!.
__________________
Osvaldo F. Zappacosta. Electronic Engineer UTN FRA from 2001. Argentine Ham Radio LW1DSE since 1987. |
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#7 |
diyAudio Member
Join Date: Dec 2010
Location: INDIA
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ok i,ll do that next time when i'll try some of that actions...but is there any prob caused by the frequencies which switch the gates???????/
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#8 |
diyAudio Member
Join Date: Apr 2008
Location: Carlisle, England
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You might be getting cross conduction. Do you switch the fets off quickly with a diode and charge the gate up through a resistor ? You will need a fast diode and something like a 10r gate resistor.
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#9 | |
diyAudio Member
Join Date: Apr 2010
Location: the tropics with 97% humidity
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it would be easier to everyone to help with your problem if you could attach as much pictures as possible. pictures of your pcb, pictures of your mosfet, ir2110, soldering and the signal trace at some important point.
the best post that i've came across explaining how to troubleshoot a class d design is as below: Quote:
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Thread | Thread Starter | Forum | Replies | Last Post |
problem with mosfets | rafelo | Solid State | 8 | 12th June 2007 01:05 PM |
HELP! B+ voltage problem/burning power resistor | chalieroundeye | Tubes / Valves | 1 | 6th September 2005 04:36 AM |
burning mosfets | Diogo | Solid State | 14 | 7th October 2002 12:51 PM |
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