Need help on car SMPS

DFI · 15th June 2004, 06:24 PM

Can anyone plz help me by telling me if the attached schematic is going to work ?

Thanks.

Tensop · 16th June 2004, 04:10 AM

jesus.

emre · 16th June 2004, 05:59 AM

Hi DFI,

It is not possible to tell if the SMPS is going to work or not by just checking the schematic, the PCB layout is quite critical too. So, I guess the only way to tell if this is going to work is to build the circuit and test it!

If you want to check the basic circuit (i.e. switching characteristics, loop stability) , I can recommend you to use Spice for circuit analysis( like LTspice, make a search on google).

Regards,

Emre

DFI · 16th June 2004, 01:10 PM

Thanks emre for the tip.

DFI · 16th June 2004, 05:43 PM

One more question. Knowing that the MOSFETs are IRF 1405, how much power can I achieve from this power supply ??

Tensop · 17th June 2004, 11:29 AM

the limits wont be in the mosfets. more likely the toroidal transformer and/or (if used) output inductors

sss · 17th June 2004, 01:07 PM

DFI :

man u are crazy

u are using 10 pairs of irf1405 ??? those are rated at 169A each

3 pairs will be enough for 500W smps
u cant just add million paralelled transistors to get more power , u gotta use 2 or more transformers if u really want to make a 2000KW + amp , is this what u are trying to do ???

plus :
i didnt check all the schematic but u allready got a serious problem !!
this is not the right way to connect the base transistors to the power mosfets !!!
R10 to R18 should be connected to the emmiters of Q9 and Q10 and not to each other !!
and Q9, Q10 , Q31 , Q32 should have emmiter resistors .

i guess there are more things wrong with this schematic , u better look at other circuits to see how its done

cheers

SkinnyBoy · 17th June 2004, 01:50 PM

parts will cost more than buying an amp premade....

sss · 17th June 2004, 02:15 PM

Quote:

Originally posted by SkinnyBoy
parts will cost more than buying an amp premade....

if u are doing it the wrong way.......

DFI · 17th June 2004, 02:18 PM

thanks sss for the reply. can you draw a little schematic on how to connect those resistors pls so I can understand better? I would appreciate your help.

Tensop, I am planning on using two toroids R 80/40/15 which you can find at http://www.kaschke.de/english/frames...ringkerne.html

SkinnyBo, that is not the problem. Maybe where you live the assembled amplifiers are much cheaper, but here in Romania they are very expensive. For example, a 300W RMS amp is no less than $200, and the parts here cost me about $300 and I get to have a much more powerful amp than I can buy with those money.

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16th June 2004, 04:10 AM	#2
Tensop diyAudio Member Join Date: Jul 2003 Location: Chapel St.	jesus.

16th June 2004, 05:59 AM	#3
emre diyAudio Member Join Date: Jun 2004 Location: Ankara	Hi DFI, It is not possible to tell if the SMPS is going to work or not by just checking the schematic, the PCB layout is quite critical too. So, I guess the only way to tell if this is going to work is to build the circuit and test it! If you want to check the basic circuit (i.e. switching characteristics, loop stability) , I can recommend you to use Spice for circuit analysis( like LTspice, make a search on google). Regards, Emre

16th June 2004, 01:10 PM	#4
DFI diyAudio Member Join Date: May 2004 Location: Brasov	Thanks emre for the tip.

16th June 2004, 05:43 PM	#5
DFI diyAudio Member Join Date: May 2004 Location: Brasov	One more question. Knowing that the MOSFETs are IRF 1405, how much power can I achieve from this power supply ??

17th June 2004, 11:29 AM	#6
Tensop diyAudio Member Join Date: Jul 2003 Location: Chapel St.	the limits wont be in the mosfets. more likely the toroidal transformer and/or (if used) output inductors

17th June 2004, 01:07 PM	#7
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	DFI : man u are crazy u are using 10 pairs of irf1405 ??? those are rated at 169A each 3 pairs will be enough for 500W smps u cant just add million paralelled transistors to get more power , u gotta use 2 or more transformers if u really want to make a 2000KW + amp , is this what u are trying to do ??? plus : i didnt check all the schematic but u allready got a serious problem !! this is not the right way to connect the base transistors to the power mosfets !!! R10 to R18 should be connected to the emmiters of Q9 and Q10 and not to each other !! and Q9, Q10 , Q31 , Q32 should have emmiter resistors . i guess there are more things wrong with this schematic , u better look at other circuits to see how its done cheers

17th June 2004, 01:50 PM	#8
SkinnyBoy Banned Join Date: Nov 2002 Location: Adelaide, Australia	parts will cost more than buying an amp premade....

17th June 2004, 02:18 PM	#10
DFI diyAudio Member Join Date: May 2004 Location: Brasov	thanks sss for the reply. can you draw a little schematic on how to connect those resistors pls so I can understand better? I would appreciate your help. Tensop, I am planning on using two toroids R 80/40/15 which you can find at http://www.kaschke.de/english/frames...ringkerne.html SkinnyBo, that is not the problem. Maybe where you live the assembled amplifiers are much cheaper, but here in Romania they are very expensive. For example, a 300W RMS amp is no less than $200, and the parts here cost me about $300 and I get to have a much more powerful amp than I can buy with those money.