Resistors calculator

DIAC

Like all diodes, Shockley diodes are unidirectional devices; that is, they only conduct current in one direction. If bidirectional (AC) operation is desired, two Shockley diodes may be joined in parallel facing different directions to form a new kind of thyristor, the DIAC: A DIAC operated with a DC voltage across it behaves exactly the [...]

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Square Wave Pulse Signal Generator

To overcome the challenge of creating necessary DC bias voltage for an amplifier’s input signal without resorting to the insertion of a battery in series with the AC signal source, we used a voltage divider connected across the DC power source. To make this work in conjunction with an AC input signal, we “coupled” the [...]

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The Transistor as a Switch

A transistor collector current is proportionally limited by its base current, it can be used as a sort of current controlled switch. A relatively small flow of electrons sent through the base of the transistor has the ability to exert control over a much larger flow of electrons through the collector. Suppose we had a [...]

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Organic Light Emitting Diodes

The increasing use of digital displays in calculators, watches, and all forms of instrumentation has contributed to the current extensive interest in structures that will emit light when properly biased. The two types in common use today to perform this function are the light-emitting diode (LED) and the liquid crystal display (LCD). Since the LED [...]

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Standing Waves

Whenever there is a mismatch of impedance between transmission line and load, reflections will occur. If the incident signal is a continuous AC waveform, these reflections will mix with more of the oncoming incident waveform to produce stationary waveforms called standing waves. The following illustration shows how a triangle-shaped incident waveform turns into a mirror [...]

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Series Motor

The arcing and sparking is mitigated by placing a compensating winding the stator in series with the armature positioned so that its magnetomotive force (mmf) cancels out the armature AC mmf. (Figure 14.1) A smaller motor air gap and fewer field turns reduces lagging reactance in series with the armature improving the power factor. All [...]

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Mutual Inductance and Force

A transformer is constructed of two coils placed so that the changing flux developed by one will link the other, as shown in Fig. 8.1. This will result in an induced voltage across each coil. To distinguish between the coils, we will apply the transformer convention that the coil to which the source is applied [...]

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Mesh Analysis

The Mesh Current Method is quite similar to the Branch Current method in that it uses simultaneous equations, Kirchhoff’s Voltage Law, and Ohm’s Law to determine unknown currents in a network. It differs from the Branch Current method in that it does not use Kirchhoff’s Current Law, and it is usually able to solve a [...]

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What is Network Analysis?

Generally speaking, network analysis is any structured technique used to mathematically analyze a circuit (a “network” of interconnected components). Quite often the technician or engineer will encounter circuits containing multiple sources of power or component configurations which defy simplification by series/parallel analysis techniques. In those cases, he or she will be forced to use other [...]

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