| EWorkshop1708 |
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? |
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| Eva |
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. |
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| sivan_and |
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 |
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| EWorkshop1708 |
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. |
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| Eva |
| MOSFETs are superior for 12V switching applications. Don't even try if you don't have any specific low-voltage switching bipolar transistor. |
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