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ground wire guage

readymix said:
On a shielded cable, like co-ax, the eddy currents would develope on the shield and are shunted to ground. Thus not interfering with the signal on the center conductor.

Beyond that you could send signals on a tri-ax twisted pair cable in out of phase pairs. Thus virtually no signal loss. Then add in a few optical isolators and you get near perfect signal transmission........Then you need to deal with the eddys that would remain in the ground plane.

How many people did I loose on that one:eek1:
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I follow, up to optical isolators; do you mean glass?
Here's a trick to bleed the current from the shield, connect only one end. Thats tricky in application because you have to create a labrinth, without contact, at the open end.
 
Not just glass. Like an LED and a reciever. It acts like a 1:1 trasformer for the electrical isolation form one side of a circuit to the other.

I have heard of just connecting on side of hte shield in a spark plug wire application. But I do know for a fact that it does not work on freqs around 60-90Mhz, and in area of 8-10Ghz.
 
readymix said:
Not just glass. Like an LED and a reciever. It acts like a 1:1 trasformer for the electrical isolation form one side of a circuit to the other.

I have heard of just connecting on side of hte shield in a spark plug wire application. But I do know for a fact that it does not work on freqs around 60-90Mhz, and in area of 8-10Ghz.
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If anyone else is following along, speak out, otherwise we'll take this offline. We gonna get technical.:D
 
readymix said:
Not just glass. Like an LED and a reciever. It acts like a 1:1 trasformer for the electrical isolation form one side of a circuit to the other.

I have heard of just connecting on side of hte shield in a spark plug wire application. But I do know for a fact that it does not work on freqs around 60-90Mhz, and in area of 8-10Ghz.
Click to expand...
Hmmm, glass, LED, transformer; thats features for optimizing gain, yes? I'm coming from power and EMI fields. For the spark plug wire example, the shield just terminates with only silicone insulation at the boot, big EMI leak from the core, yes? To get the most shielding, the metallic external shield needs to terminate inside, but not electrically bond to a metallic shell, with as tight as labrinth as possible. I was not able to test a sample of this configuration.
Which is the primary frequency of the ignition, the Mhz or Ghz?
Actually, probably the best way to shield plugs would be to run the sleeve all the way the cyl head, and deal with the open end at the dizzy.
 
roadnotca said:
Hmmm, glass, LED, transformer; thats features for optimizing gain, yes? I'm coming from power and EMI fields. For the spark plug wire example, the shield just terminates with only silicone insulation at the boot, big EMI leak from the core, yes? To get the most shielding, the metallic external shield needs to terminate inside, but not electrically bond to a metallic shell, with as tight as labrinth as possible. I was not able to test a sample of this configuration.
Which is the primary frequency of the ignition, the Mhz or Ghz?
Actually, probably the best way to shield plugs would be to run the sleeve all the way the cyl head, and deal with the open end at the dizzy.
Click to expand...
Nothing to do with gain really, Just transferring a signal between two things while keeping them completly isolated form each other. Mainly used for logic circuits but have been designed for other apps.

On a spark plug wire, if not properly designed there is a huge amount of EMI coming from it. All the HiPo wires that advertise very low resistance are the worst. A good set of resistor core wires and plugs will emit the least amount of EMI/RFI. Then the shielding could be an afterthought.

The freq range for an ignition system is between 15-150Hz. The same rate at which the plugs fire. That is why it interferes with signals in the AM band.....you can hear it on your AM/FM radio. With freqs as low as that, the shielding would be fairly effective even without a tight weave. The gapscould be pretty large and still be effective against most of the EMI/RFI.
Higher freqs require smaller gaps to act on the signal. It all has to do with the 1/4 wavelength theory.

Now.... at a freq as low as 16Hz the open end of a spark plug wire shielding is much smaller than the wavelength, this would allow even the open end of the shielding to act as "electrically" closed.
Along the same lines, having an open end on a 9Ghz line would require a much tighter weave to work.

Just look at your microwave oven....How come the RF energy does not cook the food that is sitting on the shelf. Glass does NOT stop RF.
The metal screen on the oven’s door reflects the microwaves. It does this because the holes are much smaller than the wavelength.
 
readymix said:
Nothing to do with gain really, Just transferring a signal between two things while keeping them completly isolated form each other. Mainly used for logic circuits but have been designed for other apps.

On a spark plug wire, if not properly designed there is a huge amount of EMI coming from it. All the HiPo wires that advertise very low resistance are the worst. A good set of resistor core wires and plugs will emit the least amount of EMI/RFI. Then the shielding could be an afterthought.

The freq range for an ignition system is between 15-150Hz. The same rate at which the plugs fire. That is why it interferes with signals in the AM band.....you can hear it on your AM/FM radio. With freqs as low as that, the shielding would be fairly effective even without a tight weave. The gapscould be pretty large and still be effective against most of the EMI/RFI.
Higher freqs require smaller gaps to act on the signal. It all has to do with the 1/4 wavelength theory.

Now.... at a freq as low as 16Hz the open end of a spark plug wire shielding is much smaller than the wavelength, this would allow even the open end of the shielding to act as "electrically" closed.
Along the same lines, having an open end on a 9Ghz line would require a much tighter weave to work.

Just look at your microwave oven....How come the RF energy does not cook the food that is sitting on the shelf. Glass does NOT stop RF.
The metal screen on the oven’s door reflects the microwaves. It does this because the holes are much smaller than the wavelength.
Click to expand...
Exactly, I'm used to shielding for stuff out to like 80Ghz, IE, gaps <.010.
opfor2, readymix is doing the good job of relating it back to everyday applications, food is a good one.:haha:
 
roadnotca said:
Here's a trick to bleed the current from the shield, connect only one end. Thats tricky in application because you have to create a labrinth, without contact, at the open end
Click to expand...
This is pretty common practice with shielded wire in aircraft applications.
 
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