Which Core Material for an SMPS.

[si2030]

The answers have been really helpful, and informative, and, as a consequence, beg further questions.... thank you for you patience on this.

Another question regarding cores.

I have an old TV flyback minus the turns and air gap so just the core. Using two of these, in an "E" formation (next to each other), could you conceivably use it as an SMPS core... I know they operate as a flyback at, I think, a frequency of ~25kHz so the frequency seems correct for an SMPS... are there any show stoppers with this?

One side is square and the other leg is round... if you put two together I suspect you would use the square leg side with another core to ("E" format) and wind on the turns on this square leg)... will having the other leg being round have a detrimental impact on the system?

 

[Ubergeek63]

The answers have been really helpful and informative and of course the these answers always seem to through up new questions as a consequence.... thank you for you patience on this.

Another question regarding cores.

I have an old TV flyback minus the turns and air gap so just the core. Using two of these, in an "E" formation (next to each other), could you conceivably use it as an SMPS core... I know they operate as a flyback at, I think, a frequency of ~25kHz so the frequency seems correct for an SMPS... are there any show stoppers with this?

One side is square and the other leg is round... if you put two together I suspect you would use the square leg side with another core to ("E" format) and wind on the turns on this square leg)... will having the other leg being round have a detrimental impact on the system?

you cant, but you dont need to you have a gapped TOROIDAL core. as a flyback it MUST have a gap. It is in the form of nonmagnetic material in the core mix.

Dan

 

[si2030]

So the ferrite material in a TV core is unsuitable - is that upshot...? I realise that you can remove the gap easily.

So knowing that the air gap can be removed altogether. For operation as an, off line high frequency transformer SMPS and not a flyback, can this topology be operated by this type of core (obviously ungapped)?

 

[ronsimpson]

So the ferrite material in a TV core is unsuitable - is that upshot...? I realise that you can remove the gap easily.

So knowing that the air gap can be removed altogether. For operation as an, off line high frequency transformer SMPS and not a flyback, can this topology be operated by this type of core (obviously ungapped)?

I wind TV blyback transformeres. The core is fine for a SMPS. You can use layers of tape to hold the gap. I have sheets of plastic of different thicknesses. The TV transformer had the bobbin on the round leg. You can wind on any leg. For a forward SMPS (not flyback) I would remove the gap. The TV core is probably a CC or UU and will work fine. You can, for 2x more power, put two together to make EE. You don't have to make a EE. If you need 2x more power then you can parallel two UU cores to make a larger UU core. This is not common.

 

[si2030]

I apparently have to spread some reputation around before giving it to you again... at least I tried.

Really good answer and again the confusion has been reduced... Thanks Ron

 

[Ubergeek63]

I apparently have to spread some reputation around before giving it to you again... at least I tried.

Really good answer and again the confusion has been reduced... Thanks Ron

sorry ... i thought i said the flyback core was fine...... a tv flyback is *technically* an SMPS