UCD 25 watts to 1200 watts using 2 mosfets

[CPX]

Schematic seems ok...but pin 1 at lm311 should be at -5v,it is a fixed frequency carier class D amplifier.
If you find it complicated you ay use a self oscilating topology.
Here is lorylaci's schematic(improved version on the original one in this thread)

An externally hosted image should be here but it was not working when we last tested it.

Modified level shift with pop free start and stop and with standby/protection control.

An externally hosted image should be here but it was not working when we last tested it.

 

[irvynejay]

hello to everyone i just want to ask if i use IRFB4227 do i have to change the gate resistors ?im currently using irfp250 with 27r gate resistor,,any advice

 

[CPX]

Yes,resistors in original schematic are to low.
Decrease gate rezistors la 16 ohm and dead time resistor in the level shifter to 80 ohm.

 

[irvynejay]

ok thanx ,,one more thing if i use ir2113with irfb4227 is there any changes on parts?
\

 

[stewin]

hi cpx where is the level shifter resistor situated in your schematic?

 

[CPX]

In the above schematic(the second), level shifter resistor is r4..it has 70 ohm..bur for irfb4321 i use 47 ohm and 15 ohm gate resistors,for irfb5615 i use 60 ohm and 27 r gate resistors...as a rule i chose the smalest values possible where shout through is only slightly visible on residual.

 

[stewin]

i am guessing it is r2 120R in the first diagram?
and what value if using irfp 250?

 

[CPX]

Yes r2 in first schematic..
I have not not tested irfp250 so i do not know.Try 80 ohm and go down from there since irfp250 is hard to drive..

 

[opor]

Hi,
I follow lorylaci's schematic(improved version on the original one in this thread) .Noise is improved . But sound is still too bright compare to other amps that I have build.

 

[opor]

Hi,
I follow lorylaci's schematic(improved version on the original one in this thread) .Noise is improved . But sound is still too bright compare to other amps that I have build.

With C17 is 150pF.

 

[CPX]

Define""to bright". In my experiments i found frequency response to be pretty liniar(+-1.5 db 20hz-20khz) with 8uH inductor and 300 khz switching...

 

[opor]

With C17 is 150pF.

I mean sound is harsh .

 

[CPX]

Define "sound is harsh".I do not understand such staments...i need measurable parameters.
Maybe you have to much distorsions...try to measure THD and IMD...

 

[andrewlebon]

mosfet

Manufacturer Part #:
FDA69N25
Manufacturer:
Fairchild Semiconductor
Description: MOSFET 250V N-Channel MOSFET

Silverlight Page 2,739, Mouser Enhanced Catalog
PDF Page 2,739, PDF Catalog Page
PDF Data Sheet
Images are for reference only
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Specifications
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My Notes

Manufacturer: Fairchild Semiconductor
Product Category: MOSFET
RoHS: RoHS Compliant Details
Transistor Polarity: N-Channel
Drain-Source Breakdown Voltage: 250 V
Gate-Source Breakdown Voltage: +/- 30 V
Continuous Drain Current: 69 A
Resistance Drain-Source RDS (on): 0.041 Ohms
Configuration: Single
Maximum Operating Temperature: + 150 C
Mounting Style: Through Hole
Package / Case: TO-3PN
Packaging: Tube
Fall Time: 220 ns
Minimum Operating Temperature: - 55 C
Power Dissipation: 480 W
Hi
greetings can this mosfet be used in ucd 1200 as IFB4227 hard to find here
warm regards
andrew lebon

 

[CPX]

andrewlebon:
It has a huge Reverse Recovery Charge(5700nC),you wll se very big comutation spikes and EMI.
You never reponded to my last PM..

 

[gerry_morales]

@stewin , opor
hi guys here is my new bridge class d

 

[irvynejay]

Good job Gerry go go go go pinoy

 

[gerry_morales]

ready to test

 

[rungrat_navy45]

hello gerry_morales
look good .
I am interested also...

 

[opor]

Hi, gerry_morales. Look nice. How about sound?
I am trying to modify mine because it seems too harsh compare to AB amp.I have not any measurement device but my ears.