I have been thinking about Electronics constantly since 2016. I had a box where I would keep all the nice I suctors and Transformers I salvaged. I literally had a box dedicated to them BECAUSE I had no idea how to use them but I knew they were prohibitively expensive to purchase new. So whenever I found one in an old sidewalk come up from a 1980s beta max or from a Cathode Ray Tube I would throw it in the box assuming I would figure them out one day.

But that day never came. I knew Faradays law, Lenz Law, Maxwell’s Equations, Ampere’s Force Law, Gauss’s law…I knew that motors required flyback Diodes to dissapate the back EMF generated upon suddenly stopping. I knew that magnetism was involved somehow with the performance of Transformers, I even eventually figured out that the Laminated Iron Core of non continuous interwoven Layers prevented losses from occuring due to the formation if Circular Eddy Currents.

What I did not know was that the wave propogation of EM waves (or for simplicity let’s just say light) that lights waves were propegating through a vacuum because when at zero volts AC (when the rate of change in current is largest as it crosses zero) the magnetic flux, of change n agnetic force, was at it’s largest. I did not know that like back EMF resisting changes in current through self-indutance, that there is a demagnetizing field within the ferromagnetic material that causes the magnetism to decrease in the medium. I did not know that the magnetic field was due to the changing force due to magnetism at the poles of the magnet, that is to say, Maxwell’s Equation for the Divergence if the Magnetic field is zero because the field is the magnets way of demagnetizing itself outside of the material because within the material their is a net magnetism that generates a North and South Pole.

I did not know that this results in Magnetic Hysteresis which contributes perhaps the most considerable effect to wave propegation as magnetism is not the aggregate flow of charged particles with very low mass, magnetism is not bound by mass or gravity.

I did not know that recorded magnetic data is not stored as discretely sampled values like computer memory is but is stored via it’s rate of change, hence why hard drives are rotating disks while RAM has no moving parts, yet must be always supplied with a voltage to retain data.

I did not know how to use an inductor, I did not know what calculations are necessary, I did not know how reactive inductance and reactive capacitance related to impedance, I did not know that magnetism is a result of iron having a 3D valence shell with 6 electrons, two are paired in opposing spin while the other four are not paired and naturally tend to form a Body Centered Cubic Crystal Lattice that aligns the unpaired electrons along the cubes four edges (if viewed as a cube these are the four edges that are vertical. Only iron has this ferromagnetic property because the cubic Crystal having one atom at it’s core is the only electron formation that creates the phenomena of filling higher energy layers before filling the valence shell.

There is so much more, so much more, but a tape deck will require you to spend maybe $20 to buy two broken ones you can Frankenstein into one working unit. It will be the inly time you will have the opportunity to work with inductors and magnetism in a non academic way (that is, I had only knew about magnetism through research, and we all know that doing it with your hands provides 1000x better information). Your only opportunity these days would be EMI concerns when designing PCB, but even the guys doing that started out just winging it and didn’t know the reason why the two large inductors in an audio speaker passive crossover system are orthogonal with regards to each other, the voice coil, and the large torroidal impedance Transformer for driving the speaker.

Here, Maxwell’s Equations are the reason electricity is even a thing.

Equation one states that an electric field will form when there is a difference in voltage between two points. Even though they are not connected. This can only be due to the chang magnetic Field of Faraday’s law but there is no conductor, so the demagnetizing force within the charge is creating an equal magnetizing force outside the charge, but the magnetizing force never changes because the force demagnetizing nit is the same force creating it, the energy is conserved because the Divergence of. Magnetic Field is Zero which is Equation Two of Maxwell’s Equations.

Number three is Faraday’s law with Lenz law, perhaps the most important Equation ever created in regards to it’s effect on society as it allowed us to produce electricity, and it remains the inly way we can do it (spinning a coil within a perpendicular magnetic field.) An electric field with a magnitude proportional to the rate of change in magnetic flux is generated in opposition to the current thag is generating the magnetic field lines surrounding the coil itself yet perpendicular to one another in each case.

Equation 4 is Ampere’s law relating how magnetic field forms from the current through a conductor and the electric field between two charges separated by some permiable dielectric are diffuse only because they have a continuous magnetic force.

H is Magnetic Force around a straight wire and us equal to 0.1*I/the radius of the field lines at that distance the wire. When coiled the equation is H=..4πNIA/L as the 1d wire forms a 3d Cylinder made of concentric 2D coils which is integrated into that form as L is length, A is 2D Area and π provides the 4th order need when integrating a 3D Volume. Imagine those distance variables we’re all represented by x, you would have H=.4*x^4*I, the derivative would be H=.4/4x^3 which is represented by radius for two directions and the 3rd direction is the direction of current flow. In the 4th order integral N is a function of how tightly wound a coil if length L is, which is related to the Area A, resulting in the inner magnetic force having a near uniform linearity.