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APM & Electronics 101

205.162.100.130

Posted by Steve Eddy on June 17, 2000 at 13:10:58

APM wrote:

Let me ask you a stupid question... If the ac plug is plugged into the wall outlet and the wall outlet is wired with hot and neutral in and out lines and let me state again the ac plug is plugged into the wall outlet, how is it possible that the ac plug cant interact with the current flow going through the wall outlet. Last I checked those little blades inside the outlet were actually live. Do you see the kicker on how the ac current flows through the ac plug. I could understand your theory if we never plugged it into the wall.

There is no "in and out" that has current flowing through the blades of the outlet without there being some complete circuit between the hot and neutral blades. Perhaps you're a bit confused (putting it mildly) by the four screw terminals (not counting the safety ground terminal) on an AC outlet. They use four terminals to make it easier to wire up the AC outlet if the outlet is to be placed somewhere in the middle of the circuit rather than at its terminus. But the outlet might just as well have two screw terminals forcing you to double up the wiring on each one unless it is the terminus.

Here's a scan of one side (the neutral side, since the screws are silver instead of brass colored) of a common AC outlet:

Please take note of the "jumper" between the two screws (it's normally bent over 90 degrees and not so readily apparent so I flattened it out for this image). When you have such an AC outlet wired in the middle of the circuit, you might consider one screw terminal to be the "in" and the other screw terminal to be the "out."

However, when there is current flowing through the AC line to another downstream outlet, all the current flowing "in" and "out" of this outlet is flowing through the "jumper." Unless the blades are completing a circuit by having some sort of load tied across the hot and neutral blades, there will be no current flowing through the blades.

No current through the blades, no magnetic field in the blades. There will be a magnetic field in the AC lines and there will be a magnetic field in the jumper since that is what the current is flowing through, but current flowing through the jumper does not cause current to flow in the blades.

Now when you mention the wire is wrapped around the ferrite you do mean looped through the ferrite where the magnetic field is because this is how we lower the frequency range of the ferrite by the number of loops and spacing in the wire.

Yes, I mean looped through the ferrite. But as far as the zip cord is concerned, it doesn't matter since there's really no current flowing through the zip cord anyway since it's an open circuit.

In order to establish a magnetic field that is where your wrong. The insertion of the ac plug alone with the attached ferrite is the magnetic field. By using the wall outlet to channel the ac current (never breaking the original circuit) and inserting the magnetic field created by the ferrite via the ac plug you are able to choke both the hot and neutral lines. What you need to realize is there is no open circuit here. Your assuming that the ac current needs to go through the magnet to complete the circuit. And what I'm telling you it is by going through the magnetic field built up in the ac plug.

*sigh* You're not channeling any AC current anywhere but where it's already flowing, which is through the AC line and (depending where the outlet is wired into the AC line) the jumper. There is no current flowing through the blade. It's only flowing through the AC line and the "jumper." And even then there won't be any current flowing through that unless there's something downstream (toward the terminus of the line) of the AC outlet that's actually drawing current. If your AC outlet is at the terminus of the circuit and the only thing plugged into it is your "tweak" then there won't even be any current flowing through the AC line and the jumper.

The fact remains that unless you have current flowing through your zip cord, it will produce no magnetic field around it. Since your zip cord is basically an open circuit except at high RF frequencies, there's nowhere for current to flow into it or out of it. Regardless of any ferrite it may be wrapped around.

Once again here is the basic schematic of your "tweak":

All you have to do is show how current is made to flow between points A and B in the schematic. Forget your obfuscating tirades and simply concentrate on this one little (but crucial) problem. Since current only flows through a closed loop, you have to show that point A somehow meets up with point B.

se

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