I've taken apart quite a few computer PSU, and I want to make use of the EI Ferrite power transformer in them for a SMPS project. My largest transformer came from a 550W ATX PSU.
I know in a normal computer PSU, 120V is dropped to 12V and 5V by use of different Center Tapped windings on that transformer, switched at a really HF. They are wound similar to Car Amp SMPS toroids, using multiple paralleled turns of wire for each winding.
I was thinking of using the transformer backwards, driving one of the secondaries as a primary with switched 12V push pull and use the HV primary as a secondary.
Also a few of the transformers I have even have the HV primary center tapped (or have 2 seperate primaries) even though the CT was not used in the computer power supply, I could make use of is when driving an amp. I was thinking of getting +/- 50V or so.
I was also thinking that a 120V power inverter could be made from these as well.
Any thoughts?
I know in a normal computer PSU, 120V is dropped to 12V and 5V by use of different Center Tapped windings on that transformer, switched at a really HF. They are wound similar to Car Amp SMPS toroids, using multiple paralleled turns of wire for each winding.
I was thinking of using the transformer backwards, driving one of the secondaries as a primary with switched 12V push pull and use the HV primary as a secondary.
Also a few of the transformers I have even have the HV primary center tapped (or have 2 seperate primaries) even though the CT was not used in the computer power supply, I could make use of is when driving an amp. I was thinking of getting +/- 50V or so.
I was also thinking that a 120V power inverter could be made from these as well.
Any thoughts?
Taking into account the turn ratios that I've seen, you are probably going to get +-35V to +-50V right with the center tapped secondaries, however, note that nor the secondaries neither the primaries are very symmetrical, so this approach should be used with care in any push-pull arrangement.
If I remember properly, usual turn ratios are 20+20:7+7+3+3. This means two 20 turn primaries connected in series and two 7 turn secondaries for +12V output that are tapped at 3 turns in order to get +5V and +3.3V outputs. Modern higher power units will probably employ more primary turns in order to increase turn ratio and decrease the required primary current level for a given output power, just at the expense of a higher minimum operating voltage.
If I remember properly, usual turn ratios are 20+20:7+7+3+3. This means two 20 turn primaries connected in series and two 7 turn secondaries for +12V output that are tapped at 3 turns in order to get +5V and +3.3V outputs. Modern higher power units will probably employ more primary turns in order to increase turn ratio and decrease the required primary current level for a given output power, just at the expense of a higher minimum operating voltage.
It will work no problem..i remember using the same AT pcb of SMPS..removing high volt transistor drivers with mosfets..had to add a pair of pull down transistors for each arm..by modifying the circuit around drive transistors..
GOODLUCK..post all the developments will be watching this topic...
Sivanand
GOODLUCK..post all the developments will be watching this topic...
Sivanand
Well, I'm going to be trying that soon.
I'm just trying to figure out if I should use large bipolars, or go to MOSFET to drive the transformer windings...........
I have lots of high power bipolars, but few MOSFETs. I'll try to go bpolar if I can, but if I *have* to use MOSFETS instead, then I will.
I'm just trying to figure out if I should use large bipolars, or go to MOSFET to drive the transformer windings...........
I have lots of high power bipolars, but few MOSFETs. I'll try to go bpolar if I can, but if I *have* to use MOSFETS instead, then I will.
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