Inductive interference from two EM coils (aka a transformer)

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SUMMARY

The discussion centers on the operation of transformers in electronic devices, specifically addressing the misconception about power consumption when devices are turned off. It is established that even when a device is unplugged or powered down, the transformer still presents a load to the power source, which can lead to power consumption. The source coil acts as an inductor, creating a magnetic field and generating heat, while the secondary coil induces current. Therefore, turning off a device does not eliminate power draw from the source, as the transformer continues to function in a passive state.

PREREQUISITES
  • Understanding of transformer operation and electromagnetic induction
  • Basic knowledge of AC and DC conversion processes
  • Familiarity with electrical resistance and inductance concepts
  • Awareness of power consumption metrics in electronic devices
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  • Research the principles of electromagnetic induction in transformers
  • Explore the differences between active and passive power consumption
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Electrical engineers, electronics hobbyists, and anyone interested in understanding power consumption in transformers and optimizing energy efficiency in electronic devices.

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I've been wondering about this for a long time.

The little black box that you plug into the wall so you can power your electronic devices contains a general run-of-the-mill transformer.

But if the power is completely shut off to the device: not draining any current waiting for a power button to be pressed, or even unplugged from the device end so the cord is left dangling; then shouldn't the power consumption from the source (the power company's electric meter) be the same as if it were drawing the maximum that this device possibly could?

The source coil in the transformer is a simple inductor. It provides a load (resistance from the coil) which is converted to (marginal) heat and a magnetic field. The other coil induces an electric current (and a bit more heat) from the alternating magnetic field.

Whether or not that other coil uses that induced current shouldn't affect the current drained from the source, right? I mean the entire circuit of the device could be replaced with a theoretical metal plate representing the resistance of the entire circtuit (reactance and impedance not applying after AC->DC conversion takes place). Now, I don't see how drain to source inductance can make any printed circuit or conglomerate of wires or whatever induce a voltage in the source and stop the source coil from being a straight (-) ---v^v^--- (+) circuit. (that's a resitor)So there's really no point in turning my laptop computer off, right?
 
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That doesn't help at all.
 

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