Scale able class D 1250W UCD style and Non-UCD style - PCB Ready. Tested.
- Thread starter norazmi
- Start date
hi guys it seems like i have to swallow my words. this amp works fine i think with only low voltage .
>>>>i used irfp250 also changed to the wonderful irfb4227 but they all got hot at high voltage.
the high voltage i am talking about is +/- 60vlts 1 amps.
with both i tried adjusting the c 9 up to 15nf but it only reduced the heat but it did not eliminate it. the famous irfb4227 got more hot x-( x-( than the irfp250 . in both cases i used two pairs of each. below is the pcb and schema
http://www.diysmps.com/forums/showt...PCB-Ready.-Tested.&p=6425&viewfull=1#post6425
>>>>i used irfp250 also changed to the wonderful irfb4227 but they all got hot at high voltage.
the high voltage i am talking about is +/- 60vlts 1 amps.
with both i tried adjusting the c 9 up to 15nf but it only reduced the heat but it did not eliminate it. the famous irfb4227 got more hot x-( x-( than the irfp250 . in both cases i used two pairs of each. below is the pcb and schema
http://www.diysmps.com/forums/showt...PCB-Ready.-Tested.&p=6425&viewfull=1#post6425
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not yet i am also making it. but pls think of what might be causing the output heating at high voltages.
High freq may cause heating, but you reduce it with 15n, also wrong gate resistor... You use totem pole BJT's with two pairs, try without it, only one pair, maybe problem is with it.. Chack voltage at TL074, it have to be 5.1V beacuse I think that voltage have something with triangle wave form, chack aux +12V.. I really dont understand what is the problem... I started to build this amp and my transformer is +-70, it means I will have problem too..
Did you try UCD feedback?
Maybe we have to wait Azmi to help us
Did you try UCD feedback?
Maybe we have to wait Azmi to help us
I spend whole day to make this amp to work on +-70V, but nothing.... I think this amp simply cant work on high voltages... On +-70V heat is to high, distorsion is very big and you can hear swiching freq in speaker... For this we need osciloscope to determinete source of problem...
On +-50V amplifier is stabile and sound is very good, but I have problem with heat, but I use 2.2n in feedback, I'll try tomorow 4.7n to reduce heat
On +-50V amplifier is stabile and sound is very good, but I have problem with heat, but I use 2.2n in feedback, I'll try tomorow 4.7n to reduce heat
To Michelle:
Yes but how can I know which freq is with 10n (original is 820p)?
Why amp distrord on +-70, distrosion and sound is like amp cant to start oscilation, like on/off tones?
To Stewin
Yes, I tested with +-95V and IRFB4227, works fine...
I really dont understand..
Yes but how can I know which freq is with 10n (original is 820p)?
Why amp distrord on +-70, distrosion and sound is like amp cant to start oscilation, like on/off tones?
To Stewin
Yes, I tested with +-95V and IRFB4227, works fine...
I really dont understand..
In the midtime I found out that my amp on +-50V with IRFP250N, 33R gate resistor and output filter 20uH+1uF distord with 4.7nF cap in feedback, but when I put 6.8nF music is perfect...
Michel and Stewin, can you answer on my question, what is swich freq. with 6.8nF and what is whit 10nF in feedback? TNX
Michel and Stewin, can you answer on my question, what is swich freq. with 6.8nF and what is whit 10nF in feedback? TNX
is the amp tested. and
dzony please post the schema what impedance did you use and did the out put fets get hot
Basic non ucd schematich... +-50V, IRFP250N,gate resistor 33ohm, 20uH, 1uH
Get hot after 10 minutas heatsink is small an with fan 3x3 cm heatsink is cold.
Output coil is hot (T106-2)
In feedback wih 2.2nF coil is cold but amp distord, probably slow fets, with 4.7n, coil is warm but distorsion is little bit smaller, and 6.8n amp is without distorsion but coil is hot, about 60 deegress C.
Thats why I asked what freq is with 820p, what is with 6.8n and what is with 10n!? Stewin, can you answer on it..
Because its full range sound, probably freq is above 120KHz. Am I right?
Get hot after 10 minutas heatsink is small an with fan 3x3 cm heatsink is cold.
Output coil is hot (T106-2)
In feedback wih 2.2nF coil is cold but amp distord, probably slow fets, with 4.7n, coil is warm but distorsion is little bit smaller, and 6.8n amp is without distorsion but coil is hot, about 60 deegress C.
Thats why I asked what freq is with 820p, what is with 6.8n and what is with 10n!? Stewin, can you answer on it..
Because its full range sound, probably freq is above 120KHz. Am I right?
i now want to try irs amps irs1500 because it can do +/- 90vlts comfortably without stress but when i find solution i will surely post results
http://www.diyaudio.com/forums/class-d/166214-ucd-25-watts-1200-watts-using-2-mosfets-240.html