• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

passive components affected by magnetic fields?


2006-08-08 9:13 pm

I did search the forum and I apologize if I didn't find an answer to the following:

I'm just deciding on parts placement a power supply chassis. I have a few chokes, e-lamination transformers and a toroid. I'm fine with how to orient the laminations on the e-transformers and chokes.

Can anyone tell me if any resistors/caps will be affected by their proximity to the magnetic fields generated by the iron? I gather toroids do not generate much of a magnetic field and are less of a concern. Thanks for your help.
I say no problems, assuming it's a dedicated supply chassis and all resistors and capacitors are power supply related. It's more important to build a good single point ground system. I've never heard of power supply parts picking up their own noises. Of course that doesn't preclude some far-out or bizarre situation. But in general there isn't much to be concerned with.



2006-09-30 5:45 am
Good board design always takes into account the mutual coupling, both inductive and capacative, between leads, tracks, and components. This is generally due to the potential for high-frequency noise coupling through the circuit.

In the case of a 60Hz power supply the risk is certainly minimal.

It is conceivable that a very strong magnetic field could couple into the circuitry, but good design would preclude this. Keep the power supply as remote as possible.

As for the transformer field coupling into the power supply components, this could easily be filtered out as all ripple will be hopefully filtered.

A power supply does have the potential to oscillate and couple high frequency oscillations into the surrounding circuitry. There are often good conversations about how strapping the wrong capacitors across the rails will make things worse. Studying is the best solution. Ground loops are a good subject to study also. Mark