Transformers are powerful electrical components which enable the conversion of a sinusoidal voltage into another sinusoidal voltage of the same frequency, but with a different amplitude.

The physical principle of induction, which is the basis of the transformer, does not work with direct current (DC).

A chopper is analogous to a transformer, but it does work with direct current.  A voltage, V, is reduced (stepped down) or increased (stepped up) to a different level of direct current.

We call this a DC-DC converter, as opposed to the transformer, which converts from alternating current (AC) to a different alternating current (AC-AC).

The chopper  underlies  switching power supplies  and the speed controllers for direct current machines.

Transformers are powerful electrical components which enable the conversion of a sinusoidal voltage into another sinusoidal voltage of the same frequency, but with a different amplitude.

The physical principle of induction, which is the basis of the transformer, does not work with direct current (DC).

A chopper is analogous to a transformer, but it does work with direct current.  A voltage, V, is reduced (stepped down) or increased (stepped up) to a different level of direct current.

We call this a DC-DC converter, as opposed to the transformer, which converts from alternating current (AC) to a different alternating current (AC-AC).

The chopper  underlies  switching power supplies  and the speed controllers for direct current machines.

A dipole is an electrical conductor with two poles (also called terminals). An electric circuit is an association of dipoles connected to one another by conducting wires.

In order for a current to flow in the circuit, one of the dipoles must be a source of current (generator) and the circuit must be closed.

• Two dipoles are in series when they share only a single terminal and, between  shared terminals, there is no branching toward another dipole.
• Two dipoles are in parallel (or in a branched circuit) if their two pairs of terminals are shared.

A sinusoidal magnitude is characterized  by an equation of the type :

V(t)=A sin(2πft+φ)

• A: Amplitude of the signal. V(t) will have the same units as A.
• 2πft+φ: the argument or phase of the function expressed in radians
• f: frequency of the signal expressed in Hertz. One sometimes manipulates the pulsation, ω=2πf, the units of which are rad.s^-1.
• Φ is the phase at the origin (time zero) expressed in radians

The Fresnel Representation, with vectors that are also called "phasors", is a means of representing a sinusoidal function  by just taking the amplitude and the phase of origin into account. This representation is very useful in optics or in electronics, for summing, taking the derivatives of and integrating sinusoidal functions of the same frequency, but of different amplitudes and phases.

An electrical circuit consists of :

• At least two components (also called dipoles because they have two poles) one of which is the generator (also referred to as the source).
• Conducting wires that connect the components to form a closed loop that enables current to flow.

Numerous forms of transpoort operate using electrical energy. Regardless of the dipole used, an electric motor is connected to the generator (not shown in the photos) by two conducting wires.

The electric power available at the terminals of a dipole is equal to the product of the current (I, in amperes, or "amps") and the voltage (E, for "electromotive force", in volts).

Remark: The colors chosen are not the conventional ones. The voltage and the current  could be direct or alternating.

The modulation of a signal is essential if one wishes to transmit it over long distances.  Modulation  also provides a means for simultaneous transmission of several signals, using the same transmission channel (Hertzian, cable ...).

Amplitude Modulation (AM) is the simplest and the oldest of modulation methods, primarily because the stage of demodulation, at the receiver, is simple to carry out.  A modulator, followed by a filter, is sufficient to obtain an amplitude modulated signal, but it should be pointed out that this type of modulation generates numerous distortions and so frequency modulation (FM)   is now the preferred modulation method.

The digitization of an analogue signal is carried out by taking several samples and translating them into binary code.  The series of codes thus obtained are then regrouped in a digital file. The advantage of such digitization lies in the ability of such file formats to undergo processing  by a computer.  In order to obtain a digitization that corresponds to the original analogue signal one must gain precision. To do this, it is sufficient to increase the sampling frequency and decrease the pace of quantization.

It is because demodulation of an amplitude modulated (AM) signal is so simple that this type of modulation has existed for so long. The fabrication of a simple envelope detection circuit  like that shown in this simulation is very simple and not costly.

Nonetheless, the rectification provided by a commutation diode produces some distortion, and this type of circuit is no longer used in high quality receivers.

Logic gates are at the basis of digital circuits. They carry out the basic functions of Boolean Algebra using digits in binary code.

This original theory, developed by George Boole in the 1830's, is at the heart of all current computer systems, which can function only with digital inputs, in binary code.

Combinational  Logic  only deals with logical functions in which the output depends solely  on the inputs.  This differs from Sequential Logic, in which the outputs also depend on inputs, but also on previous outputs ("memory" effect).

This animation only permits simulations using Combinational Logic functions.