Easy SMPS for everyone :)

[panos123]

ok..
i winder a core from cfl lamp..
3x4 turns with 0.2 mm enameled coper wire...
the ferite is too small..
it's only 5mm...:"::

 

[vorezky04]

But is it work?

 

[panos123]

no...
it doesn't work....
i have 51 volt at the outpout(the voltage is corect) but when i conect a 3amp load the voltage drops to 10 volts....
47 ohm feedback resistor is too hot.....
i have use 2watt resistor...
my outpout coil is an ei33 transformer with 28 turns ...
and i aded a 2.7 ohm resistor at the bases of the transistors...(13007)
what causes this problem?

 

[Acca]

I just follow Acca.
That is the best choice how build prototype.. Easy for modification if any mistake. :adoration:

@Acca, i will increase primer BDT to 8 Turns. Can we are increase frequency to 50Khz? If can, where need modification?

You can't.Only you can try another core,maybe it will go to 50khz.

 

[Acca]

acca can i use the small black ferite from a pc psu for base driver?

You can try.... If something get wrong,you will hear it,freq will be low if core is not adequate...

 

[Acca]

No, because the black ferrite from a PC is Filter with high permeability.

CFL BDT has high perm. too....

 

[Acca]

no...
it doesn't work....
i have 51 volt at the outpout(the voltage is corect) but when i conect a 3amp load the voltage drops to 10 volts....
47 ohm feedback resistor is too hot.....
i have use 2watt resistor...
my outpout coil is an ei33 transformer with 28 turns ...
and i aded a 2.7 ohm resistor at the bases of the transistors...(13007)
what causes this problem?

Too small feedback.
Increase primary BDT to 8 turns.
Decrease feedback resistor to 22 to 33R,use 5W one.

 

[Acca]

.
i have use 2watt resistor...
my outpout coil is an ei33 transformer with 28 turns ...

I say to use 2W ones
Don't forget gap on E33 or it will saturate (but this is not reason of your problem,only you can blow transistors)

 

[panos123]

i don't have any gap at e33 outpout inductor...
1mm gap ok?
this coil is only for testing reasons...
if everythig work ok i will use the yelow cores from ps psu...

 

[panos123]

i winded 8 turns but the problem still exist...
i used 5watt 22ohm resistor but it's too hot again....
this is my secondary...
is there any problem at the sec?

 

[Acca]

Simply your rectifier is problem.
Your inductor should have gap about 1-1,5mm and it will not saturate.
In Half bridge,you MUST use both of half periods of wave.Use bridge or center taped rectifier and you will get needed power.
Use 47R resistor and 8t. primary.

For ALL:
Use 8turns primary in BDT,works better at high power.

 

[kanon]

hi..

version to mosfets need gap.


can use this toroid for gdt

http://www.ebay.com/itm/400721351880?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

 

[Acca]

Gap is not needed in fet version,tested.

 

[kanon]

thanks.

can use this toroid for gds

http://www.ebay.com/itm/400721351880?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

 

[Acca]

Get smaller one,I use 10mm ferrite toroid high permeability and works wery good,freq. is about 50-60khz.You can use cores from RF chokes (EE or toroid or any type),tested and work very nice,both half and full bridge.You can try your core,FET version accept almost all cores
But maybe sw. freq. will be small,I don't know,there is too small data for this core.
And this is only for fet version.

 

[panos123]

i tried 6 amper 600 volt brige rectifier but it gets hot even if i don't have any load conected...
now thinks are beter..
but i have problem with feedback...
47ohm resistor get's very hot after few seconds and i measur with the multimeter 6 volt at the feedback coil...
i think it;t too low...

 

[Acca]

You can't use classic bridge rectifier,it's not designed for 20+ kHz.You must use fast diodes (BY-not all,FR,UF,BA series)
47R you can use 5W.It should get hot,it dissipate about 1,7W and voltage at bases is ok,and you should measure it with analog multimeter.

 

[panos123]

ok thank you acca...i will try tomorow with fr107 diodes...

 

[Acca]

Yes if you plan to use max 0,8A current at output.Use diode with higher current,BY500,FR302,HER605,FR604,....
It's 1A,remember....

 

[panos123]

i have some u20c20c diodes from pc psu..
they are rated at 200 volt 20 amper each...
but they are double diodes(they have 3 legs)....
can you give a shematic to show me how can i use them to rectify my smps?