TheMG: that's an attached garage, plugs are 15m cables away from the breaker panel and the other PLC is 5m in the opposite direction. I just changed the configuration to connect the PLC on the plug tha tis the closest from the breaker panel and used a 5m RJ45 cable to the PC - we'll see if it works that way because I can't change the computer place nor the bench's, it's bolted on the wall. (I don't know if I'm clear enough, have to enhance my english skills)
T3sl4co1l:
No, because the GDT will stay on after the pulse, until a fuse blows (or it absorbs too much energy and explodes..).
From what I learned on wikipedia :
a GDT once triggered will continue to conduct at a voltage less than the high voltage that initially ionized the gas; this behavior is called negative resistance. Additional auxiliary circuitry may be needed in DC (and some AC) applications to suppress follow-on current, to prevent it from destroying the GDT after the initiating spike has dissipated.
So for small voltage circuits, GDTs have to be used with other circuitry to reset it after it triggered ? One can't use it alone like a MOV ?
The bridge is a neat idea. Beware that it may not withstand MOV sized transients; or if it does, it'll be pretty big anyway, i.e., not a bad capacitor itself, at least near the AC line peaks. It could also make it worse, because the variable capacitance acts to parametrically modulate the communication waveform at 100/120Hz.
I didn't got it... What kind of bridge ?
The MOVs may not be necessary at all. Depends on your electrical environment, what equipment is plugged in nearby, and what kind of survival, over a period of years, you expect from it.
In the garage, not much: water tank, a radio, a long power cord for the vacuum cleaner. That's it. The thing is I live in Provence (south of France) when from March to June, when there are lightnings, there are huge loads of lightnings !
(I have 1 or 2 electrical equipments that blows their power board or MOVs or fuses each year !)
Kleinstein:
One could replace the over-voltage protection with a version that also includes filtering by inductors, not just an X cap.
There may be other parts (e.g dimmer, fluorescent lights, fans, ...) in the house that do to much filtering and thus have a negative influence on PLC. Another problem could be if the signal has to go from one GFI circuit to an other. Also a neighbor using PLC as well might interfere.
I forgot that: every ligths in the house are LEDs (IKEA, Philips, not chinese one with crappy PSUs inside ! For those ones, I don't turn them on, I take them apart !)
LAN over powerline is broken by design anyway: to much other units with simple filtering can stop it from working. Also emissions are sometimes to high (above legal limits) - so in principle you might be liable for interference with other radio communications.
True. But I don't want to flood the house with 10W wifi repeaters nor 40m long RJ45 cables running on every walls (already done that at work, done with it !)