Can pulsating DC current be transformed? Since pulsating DC current is changing, why doesn't it induce a changing magnetic flux in the transformer core? Is it able to induce a transformed current in the secondary coil?
 A: As long as the DC component does not saturate the core of the transformer, the (lower frequency) components of the waveform should be induced in the secondary.
Consider, for example, the output transformer of a single ended class A triode audio amplifier

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In this case, the primary current is 'pulsating' DC, i.e., the primary current varies with time but never goes through zero (never alternates) while the secondary current through the speaker has no DC component.
A: Yes surely, The pulsating DC is impure dc. Each pulse will be creating a change in magnetic flux in the transformer core.

If you see the normal ac diagram the wave from 0 to T, It is similar to your pulsating DC diagram, there is a change in flux in transformer in this case.
But it interesting to note that the transformer will give the increased or decreased voltage of the wave form that you input (step up transformer in this case).
In your case you will get stepped up voltage of the wave form that you supplied that is in your case the pulsating DC.
The transformer will work with any waveform which has a changing value with time. because changing value is necessary for change in flux.
A: I asked my physics teacher, and the reason very little current (if any) is induced is that hysteresis in the core means it will quickly become saturated if the direction of magnetic flux does not change, and hence the secondary coil will not experience change in flux.
A: Vibrators were used in 6v cars to power the HV dc of the tube radios.
https://www.radioremembered.org/vpwrsup.htm
A: We know that a variable magnetic field induces an emf which in turn induces a current( in secondary coil) however using a direct current in the primary coil will create a non-variable magnetic field (no change in flux) and so no emf will be induced in the secondary coil. This is why we need an alternating current and cannot use a direct current.
