| Electronics > Projects, Designs, and Technical Stuff |
| "over current" use of a Pulse transformer - ( or an alternative ) |
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| mrpackethead:
--- Quote from: Zero999 on December 22, 2018, 02:36:49 pm ---No, because the current doesn't flow from both sides of the tap simultaneously. It alternately flows from each side to the tap. --- End quote --- The 'power' component is nominally 52V DC ( or GND ) , and its applied at the same time to to both sides, and it flows out the CT. Its DC?? The signal component is of course is effectively AC, but the magntitude of that is very small in comparision to the power. |
| mrpackethead:
--- Quote from: ogden on December 22, 2018, 07:55:29 pm ---No matter how nice looking is mentioned TDK small footprint pulse transformer, whole idea of more powerful transformer - it's bigger. Two parallel transformers will not pass IEEE 802.3, thus such cannot be used in other than DIY/hobby short cable runs. I do not see any other solution than using more powerful, 1000mA transformer such as ETH1-460L_ --- End quote --- Why would it not pass? The real question is what the limiting factor of this part is. Its it thermal, or is it something else. ( core saturation ). I will have to find out. |
| Zero999:
--- Quote from: mrpackethead on December 23, 2018, 08:35:28 am --- --- Quote from: Zero999 on December 22, 2018, 02:36:49 pm ---No, because the current doesn't flow from both sides of the tap simultaneously. It alternately flows from each side to the tap. --- End quote --- The 'power' component is nominally 52V DC ( or GND ) , and its applied at the same time to to both sides, and it flows out the CT. Its DC?? The signal component is of course is effectively AC, but the magntitude of that is very small in comparision to the power. --- End quote --- If you're talking about the power flowing through both sides of the CT simultaneously, then of course you're right: the flux will cancel, not no net magnetic field induced in the core, both it sounds like a strange, non-standard setup, rather than how the transformer is supposed to be used. Post a schematic. |
| T3sl4co1l:
Mrpackethead has been deeply involved in PoE applications (I don't know how obvious this is from the OP or his posting history), and as far as I know this is a standard application, for which there are such transformers as linked above, as standard off-the-shelf components. :) Yeah, differential data passes by, common mode power is drawn through the CT. Everything is transformer-isolated so there should be no balance issues outside of insulation/conductor failures. Nice name change..? :o Tim |
| mrpackethead:
--- Quote from: Zero999 on December 23, 2018, 10:17:17 am --- If you're talking about the power flowing through both sides of the CT simultaneously, then of course you're right: the flux will cancel, not no net magnetic field induced in the core, both it sounds like a strange, non-standard setup, rather than how the transformer is supposed to be used. Post a schematic. --- End quote --- This is a very standard Power over ethernet set up. I'd suggest 10's if not 100's of millions of ports of POE has been done. Generic schematic is set up. |
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