UCD 25 watts to 1200 watts using 2 mosfets

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stewin

Member
Joined 2007
high guys i've sought of reduced the noise in my amp by adding 1nf between pin 2 and 3 of lm 311 and i want to try using the below scheme for the input of lm311pls advice :D also i've managed to bridge the amp ( very power full) i used just the ir2110 pins lin & hin but i've not included the feed back on the other channel but works fine, voltage 56v -0- 56v irf540 warms a little. any ideas i would appreciate . steve
 

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S

stewin

Member
Joined 2007
S

stewin

Member
Joined 2007
hi guys just curios . i haven't used a dual side pcb. but by adding 5.6k resistor before input cap. and using 4.7nf grounding with pin 3 of lm311 i've managed to sort of eliminate the noise . just wondering if i have reduced or altered the amps switching frequency and if i,ve reduced the switching frequency what frequency am i using thanks in advance stewin .
 
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ionutzxpo

Member
Joined 2009
hi stewin the carrier frequency is influenced by the output cap and inductor by reduction to 680nF you cand get 300Khz i plan to use 1uF and 30uH inductor followed by a 10 ohm/3W-100nF/100V in series filter

i think by adding that 5,6k you reduced a little the gain (i think not sure)

regards,
Ionut
 
S

stewin

Member
Joined 2007
hi guys i'm sought of having problems with my out inductor the amp is fine even in bridge mode .but the inductors are heating and the fets in a small sized sink are warm causing me to worry . there are no meters to measure inductance or ferrite core dealers available here , so i just wound 40 turns ,1.2mm wire on the normal yellow and white stripped 27mm troidal found in pc smps .
i am not sure on the inductance because no induc meter available these sides . just wondering if i could use the E core found in old pc smps instead of using the troidal one pls help and thanks in advance guys.
 
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Andrew Eckhardt

Member
Joined 2005
That core is likely to be from Micrometals. You can get the specs on the core at their site, as well as their design software, which includes data for better material types in this application. The ferrite core is probably epoxied together any there is a pretty slim chance you can get it apart with something useful left over.
 
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ionutzxpo

Member
Joined 2009
i use T130-2 from micrometals and 217 cm off 1.5mm wire all stay cool sund just great but i have a little problem now for my signal source i use MP3 media player and no audible noise is comming from spekers but if i connect the amp to computer i get some high frecv noise in spekers not to loud but becomes audible any sugestions?

thanks
 
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Tekko

Banned
Joined 2004
The yellow with white rim cores found in pc psu's are T1xx-26 from micrometals and no it is not suitable for class d, so theres your inductor heating problem.

Download this softie: Mini ring core calculator its a great tool for calculating the number of tirns for a given inductance, then type in your operating frequency and voltage and it calculates the heating of the core and the flux levels.

For my amp, im gonna take the T130-3 inductors off of a car amp i have as well as the fets: HUF75337p along with decoupling caps.
 
andrewlebon

andrewlebon

R.I.P.
Joined 2008
hi lycanik
greetings i made your pcb wanted to ask you feedback resistor 22k parallel with 330pf but you have used 22k plus 100pf is it ok?

thanking you
andrew lebon
 

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