• posted

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

Rick

• posted

Rick,

See

" 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: