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circuit design till 100MHz

Thanks to all.The power line is having 10A current at 50Hz. i know the
conductor on the line side of the transformer has to be sized for it.
i cannot use the air core as the signal i am trying to inject into the
line is very small magnitude. To have good coupling between the
primary and secondary i need strong field with air core. Am i right to
say so?
Talking more on the cores, last week i ran through many books on
magnetic cores. I came to conclusion that for high frequency the
existing cores are MnZn and NiZn cores. MnZn has high permeability and
its magnetic resonance is at somewhere in few hundreds of kHz. For
NiZn, the permeability is low and it is wideband than MnZn cores but
it still suffers from permeability roll down at few MHz. So if i take
the permeability at certain frequency and design the inductor or
transformer, at other frequency its not the same.
Please suggest any reference to read on. i am gonna get that book of
Randy and see it.
thanks.
 
M

MooseFET

Jan 1, 1970
0
Thanks to all.The power line is having 10A current at 50Hz.

That will require a moderately large wire. You may be able to use the
braid of a coax as the mains conductor. This is a good way to get
very tight coupling.

i know the
conductor on the line side of the transformer has to be sized for it.
i cannot use the air core as the signal i am trying to inject into the
line is very small magnitude. To have good coupling between the
primary and secondary i need strong field with air core. Am i right to
say so?

That isn't really true for narrow band applications. Making the
transformer resonate, can make it do a good job of coupling the power
without it having a high inductance.

Talking more on the cores, last week i ran through many books on
magnetic cores. I came to conclusion that for high frequency the
existing cores are MnZn and NiZn cores. MnZn has high permeability and
its magnetic resonance is at somewhere in few hundreds of kHz. For
NiZn, the permeability is low and it is wideband than MnZn cores but
it still suffers from permeability roll down at few MHz. So if i take
the permeability at certain frequency and design the inductor or
transformer, at other frequency its not the same.
Please suggest any reference to read on. i am gonna get that book of
Randy and see it.

http://www.fair-rite.com/ has some good information
 
That will require a moderately large wire. You may be able to use the
braid of a coax as the mains conductor. This is a good way to get
very tight coupling.

i know the


That isn't really true for narrow band applications. Making the
transformer resonate, can make it do a good job of coupling the power
without it having a high inductance.


Can u elaborate more on this please.
 
C

colin

Jan 1, 1970
0
Thanks to all.The power line is having 10A current at 50Hz. i know the
conductor on the line side of the transformer has to be sized for it.
i cannot use the air core as the signal i am trying to inject into the
line is very small magnitude. To have good coupling between the
primary and secondary i need strong field with air core. Am i right to
say so?
Talking more on the cores, last week i ran through many books on
magnetic cores. I came to conclusion that for high frequency the
existing cores are MnZn and NiZn cores. MnZn has high permeability and
its magnetic resonance is at somewhere in few hundreds of kHz. For
NiZn, the permeability is low and it is wideband than MnZn cores but
it still suffers from permeability roll down at few MHz. So if i take
the permeability at certain frequency and design the inductor or
transformer, at other frequency its not the same.
Please suggest any reference to read on. i am gonna get that book of
Randy and see it.
thanks.

http://www.micrometals.com/materials_index.html

the table at the bottom goes upto 1 ghz.
it doesnt matter if the coupling is poor as its easy to amplify the signal.
there are suitable amplifiers and transformers to drive broadband down std
telephone cables.

or do you need to receive it too ?

there are various sources of info on transmitting/receiving signals over
power lines.

Colin =^.^=
 
M

MooseFET

Jan 1, 1970
0
Can u elaborate more on this please.


Do you have a copy of LTSpice?

If not go to www.linear.com and download a copy of "switchercad3".

You have to always have a DC path to ground from all parts of your
circuit so you can't fully isolate the high voltage side.

Try making a couple of tuned circuits with 22pF capacitors and about
120nH inductors. Load one with 200 Ohms and drive the other with a
200 Ohm signal source.

Inserting a statement like

K1 L1 L2 0.25

you can set the coupling. With only a coupling of about 1/3 rd, you
will find that the power gets transfered nearly perfectly over a band
a few MHz wide around the 100MHz center.

A single turn of coax about 5 or 6 cm in diameter could be your
transformer. You need to make sure that it is mounted very stiffly so
it doesn't flex and hold it away from the nearest metal by more than
its diameter.

I suggest you get a chunk of coax and a couple of trimmers and give it
a try. A simple experiment would make it a lot clearer.
 
I do have the LTspice.

i appreciate if you can ellaborate more on the technique you are
suggesting about the coax. You can email me if uyou do not mind making
some sketches for explaining.you can email me at
[email protected]

About Randy's book, i find its more for RF designers.

thanks to all.
 
M

MooseFET

Jan 1, 1970
0
I do have the LTspice.

i appreciate if you can ellaborate more on the technique you are
suggesting about the coax. You can email me if uyou do not mind making
some sketches for explaining.you can email me at

Others may be reading so I'll keep it here.

Equipment:

1 15 OZ can of Pilgrim Joes Clam Chowder
1 Stiff card or thin plywood
25cm coax
1 Spool of tape
1 Sharpy brand marker
1 Tool kit
1 Tape measure
2 3cm #14 wires with stripped ends
2 Trimmers

Procedure:

1
Place the can in the center of the card.
2
Use the marker to outline the can.
3
Remove the can
4
Find the center of the coax and afix it to the card along the line.
5
Form the two ends of the coax evenly along the line
6
Find a point 1cm past where the two ends meet on each end.
7
Strip the coax jacket from the ends to the points found at step 7

8
Push the braid from the ends of the coax towards the middle to
loosen it
9
Cut the braid at 2 cm of length
10
Unwrap the braid so that it is on one side of the coax and twist
the strands together.
11
Strip and solder the #14 wires to the braids on the ends.
12
Wrap the exposed conductors in tape
13
Twist the #14 wires together to form a twisted pair
15
Solder the #14 wires to one trimmer.
16
Twist the coax centers together and trim at 5cm.
17
Stip the coax centers to expose 0.5cm of conductor
18
Use tape to hold the coax centers together
19
Attach the coax centers to the second trimmer
21
Apply large amounts of tape to holed the assembly on the card
while you experiment with it.
22
Connect the mains wire to the #14
23
Connect the applied signal to the centers.

Its a prime number of steps so it must be good.
 
i do have the LT spice. if you can further ellaborate this coax thing
it would be better. Picture speaks a thousand words. any sketches
would be better to understand. You can email me at
krishmaniacAThotmail.com.

I find the randy's book more for the RF designers.
thanks.
 
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