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Remove hum (50/60 Hz) of mains supply transformers in audio circuits to zero by moving them (demo)



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Please read the textbox. Here I show about how to mount a mains transformer (110 V AC/230 V, 50/60 Hertz) for a sensitive audio circuit.
Aim is to push down the electromagnetic stray field (read 50 Hz or 60 Hz induced into a Hi Fi circuit or a not Hi Fi circuit) to the absolute minimum level.

This video shows how to do that.

By moving the mains transformer (50 Hertz/60 Hertz type with a steel/iron/laminated core) to the position where the electromagnetic stray field has its absolute minimum influence on (say) a sensitive audio pre-amplifier on a circuit board.

Hum of the transformer is related to the position of the laminated steel core, say opposite to the audio pre amps.

Even with very properly shielded audio (pre) amplifiers this can happen: hum at 50 Hertz or 60 Hertz, especially when the volume controls are on the “zero” level.

Especially in this situation the stray hum out of the mains transformer that supplies it all can pop up.

That is in fact very strange: all volume controls down and still hum, why?
Is this a serious problem?

Yes and no. It depends.

Yes: when you are working in the real Hi Fi range and want to have audio amplifiers that are completely (read: absolutely) silent on all the volume control settings.

No: when you want to have an audio amplifier where this slight hum falls back (more ore less completely diminishes) when your volume control is on (say) 1/10 of its level, going up.

In that case the signal to noise level (= the ratio) goes up substantially so that you don’t hear that hum any longer.

It “falls away”, compared to the audio level output of (say) a tuner, pickup, MP3 player, CD player, whatever other source with a (say) output on line level, that is (say) 0,8 V – 1 V AC (audio) out, connected to the (a) pre amp. or end amp.

Important: about stray inductance: keep it (stray inductance) out of a mains transformer, keep that transformer (50 Hertz/60Hertz) as far away as possible to take away all electromagnetic influences on (say) electromagnetic deflection plates in a cathode ray tube, made for electromagnetic or electrostatic deflection.

In the past 1980's -1990's I made both circuits, E.M. deflection and electrostatic deflection Cathode ray tube circuits.

In both cases the mains transformer position (230 V/50 Hertz) supplying the circuit was very critical; they had to be be mounted far away from the CRT tube. So far from the base socket and/or (it was tested out).

I had to use to some peculiar positions of the mains trainsformer supplying it all (50 Hertz/230 V in my case) to make that the EM stray field did not distort the dot on the oscilloscope screen, making it egg-form or even distorting it to to a small “line” (line width was approx. 1 mm).

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I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube. Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 20 January 2022.
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Audio
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