Electronic

Logic Gates

A logic gate is a physical device that performs a logical operation on one or more logical inputs and produces only one logical output. The input is the signal or data that fed into a logic gate whereas the output is the result of processing the inputs by using the operation of the logic gate. … Read more

Transistor as an Automatic Switch

The Transistor as an Automatic Switch A transistor can be used as automatic switches. In the diagram above, the bulb is off when the collector current is off or very small. It is switched on when the collector current becomes large.  We have learned that in a transistor, the collector current is controlled by the … Read more

Transistor as a Current Amplifier

Transistor as an Amplifier The major application of a transistor is as a current amplifier. A transistor can be used to amplify (‘magnify’) current changes because a small change in base current produces a large change in collector current. A simple transistor amplifier circuit is shown in Figure 1 below. (Figure 1) The graph in … Read more

Current in Transistor

Current in a Transistor The current flows in the base, emitter and collector are called the base current (IB), the emitter current(IE) and the collector current(IC) respectively. The figure below shows the direction of the current in an npn transistor. In general, IE is related to IB and IC through the formula IE = IB … Read more

Connection of Transistor

Connection of Transistor The terminals of a transistor must be connected to the terminals of a cell correctly to avoid damaging the transistor. Transistor should be connected in such a way that the emitter-base circuit is forward bias the collector-base circuit is reverse bias. Example: Emitter-Base: Forward Bias Collector-Base: Reverse Bias Connection: CORRECT Example: Emitter-Base: … Read more

Transistors

Transistors A transistor is a double p-n junction semiconductor with three terminals,  the emitter (e),  the base (b)  the collector (c). Figure 1 below shows the illustration of a transistor. It looks like a combination of 2 p-n junction diodes. (Figure 1) In a transistor, the emitter emits charge carriers (free electrons or holes). The charge carriers … Read more

Capacitor Smoothing

Smoothing In the circuit above, the `one-way’ direct current flows in a series of surges with brief periods of zero current in between.  These surges can be partly smoothed out by connecting a large capacitor across the load. The capacitor charges up when current flows from the diode, then discharge through the load when the … Read more

Full Wave Rectification

Full-wave Rectification The figure above shows a circuit to produce full-wave rectification.  Using an ingenious arrangement of diodes, called a bridge rectifier, this reverses the negative half of each a.c. cycle, instead of just blocking it.  The result is that current always flows in the same direction through the load, no matter which way it … Read more

Diodes as Rectifiers

Half-wave Rectification Diodes are also known as rectifiers. They can be used to change a.c. into d.c., a process called rectification. A simple rectification circuit is shown in the figure below. The final waveform on the screen is the positive half only of the original a.c. waveform – hence the term ‘half-wave’ rectification. Half-wave rectification: … Read more