Re: x10 blocking circuit trade-offs...

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Fri, 18 Nov 2005 21:49:58 GMT, "Rick Bolen \(HM\)" <rickbol@xxxxxxxxxxx>
wrote in message  <a0sff.1385$3o6.699947@xxxxxxxxxxxxxxxxxxxxxxxx>:

>hello all,
>
>I'm planning to build an x10 [120kHz] filter that I've modelled in PSpice.
>One design I found on the internet, and the other I derived by playing
>around with available L\C values out of my Mouser catalog.
>
>The design I derived has a wider notch bandwidth than the Inet design (at
>any given load_Z). The center frequency of both designs is 118kHz, but with
>my derived design I still get -15dB of signal attenuation at 120kHz at 1Kohm
>load impedance.
>
>Based on my modelling, the higher the load impedance, the more narrow the
>notch bandwidth... and if you're off of the target frequency, you may not
>achieve much signal attenuation at all!
>
>So my questions are:
>
>1) what is the range of impedance of a typical house leg circuit at 120kHz?
>10ohm? 1kohm? 10kohm? ???
>
>2) would L\C values of 0.01uF and 180uH present any obvious difficulties?
>
>X10 Blocker Circuit:
>
>                180uH           180uH
>  BLACK  ----+---))))))---+---))))))---+----  BLACK
>             |            |            |
>             |    | |     |     | |    |
>             -----| |-----+-----| |-----
>                  | |     |     | |
>                 0.01uF   |     0.01uf
>                        -----
>                        -----
>                          | 1uF
>                          |
>                        WHITE
>
>Thanks for any advice,
>
>Rick
>

Rick,

See http://www.ipcf.org/doc/Power_Line_As_Access_Medium_-_A_Survey.pdf

" Single - phase lines behave largely as inductive loads, impedance magnitudes
going up with frequency, in the range below 100Khz, variation being typically
from 1-2 ohms at 10 Khz to 10-20 ohms at 100 Khz. In this range, the impedance
is largely that of the DT which can be approximated by an inductance of about
25 mH shunting a series connection of 8 ohms resistance and 50 nF capacitance.
Other loads appearance as shunt impedances across this connection. Beyond 100
KHz, repeated series and parallel resonances are observed depending on the
loads, impedances often becoming as high as 100 ohms at 100 Mhz. The line
itself typically has a capacitance of 30-60 pF/m, inductance of 0.3-0.6 mH/m,
and resistance of 0.040 ohms/m, leading to a characteristics impedance of
75-150 ohms. Typical loads like TV, Heater etc have impedances much less than
the line impedance. "

Also  Filippo Giannetti's work. His original and subsequent sites appear to be
moved/down, but here's an alternate:

http://edxc.ifrance.com/edxc/plc.htm

"Line impedance. Experimental measurements reported in the technical literature
demonstrated that a typical power line exhibits a low value impedance. For
instance, the results reported in Ref. [1] indicate an impedance of about
0.1-100 [ohms] in the frequency range100 kHz-1 MHz, while the results reported
in Ref. [8] indicate an impedance of about 10 [ohms] in the frequency range10
kHz-100 kHz. "


Also many other good references in these two papers.


... Marc
Marc_F_Hult
www.ECOntrol.org