Recent content by tech99

How would the individual lines in the comb be modulated with different data streams? As you may know, the technique is used for digital TV and mobile phones. By splitting a high speed data stream into many parallel ones, the system becomes much more robust and insensitive to echo distortion...

I presume the charges are accelerating and so would seem to radiate in the directions 45 degrees to the axes and zero along the axes.

Any new invention is going to be really painful to launch, with competing interests trying to strangle the idea at birth. Ridiculous rules and regulations pop up from nowhere. Such was the case with Sebastian Ferranti, an Englishman who (according to Wiki) invented the alternator and had the...

With present day standards, the International Electrotechnical Commission and the UK IET define 50V AC and 120V DC as the upper limit for electric shock. There is also another UK standard where 110V AC centre tapped to earth may be used, as on building sites. So 73V is not regarded as safe...

It looks to me that each sphere is radiating into a sky which is slightly obstructed. So the combined radiation measured at a great distance will initially be less than the sum of the two free space powers. But when the two objects reach equilibrium the power measured at a great distance will be...

I also remember and using 2-way adapters for bayonet fittings, so you could have a light bulb and a power take off. No earth pin of course.

I remember that in the 1940s in the UK, we had power points, but very few. The bayonet light fitting was often used for electric irons. After WW2 the electrical systems were modernised with the introduction of ring circuits and the special safety plug we still have today.

I think so. I believe the wave has the same propagation constants and Zo as the TEM wave, so you don't notice it. It is of small magnitude in a coaxial cable but is important for widely spaced conductors.

As far as I can see, I think you do get an electron "wave of compression" travelling along a transmission line in addition to the TEM wave. The longitudinal E-field is developed across the inductance-per-unit-length of the line. This applies to any conductor when the applied voltage varies.

I would endorse the reply #5 from DaveE. Piezo devices have very high resistance but some capacitance. There is no disadvantage in wiring them is series and working into a high impedance amplifier. But be careful about cable capacitance, as this will form a potential divider with the piezo...

So far as I can see, and I may be incorrect here, when the switch is closed there is oscillation, which is gradually damped out by resistive and radiation losses. The energy we extract by the oscillation was contained within a radius of half a wavelength of the oscillation. If you discharge a...

I assume the wire is the same gauge, copper, enamelled? If so I strongly suspect the material of the core as the problem.

It is easy to try quenching the core if making an electromagnet. I have found it works on nails used by pupils as cores for making magnets. The untreated steel retains its magnetism and the quenched steel does not.

I have often turned nails into "soft iron", by heating and quenching them, for pupils making magnets. This makes the core lose its magnetism when the current stops.

Thank you. I think the annealing process makes the steel magnetically "soft", so it does not retain magnetism.