Tag: Analogue electronics
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Zener Diode and Emitter-Follower/Series Voltage Regulators
Almost all electronic devices and circuits need a dc source of power for their operation. While batteries and dry cells can be used as a form of dc power supply, their voltages are usually low and they require frequent replacement; additionally they are costly compared to regular dc power supplies. The domestic ac supply can…
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Gunn Diode – Features, Operation & Applications
Features of a Gunn Diode A gunn diode is made up of only N-type semiconductor which is typically sandwiched between two metal conductors. The central section is usually lightly doped N– surrounded by heavily doped N+ layers. The central section is N-gallium arsenide whereas the two outer sections undergo epitaxial growth from GaAs with increased…
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Voltage Doubler Circuit Operation
A voltage multiplier is a specialized rectifier circuit capable of producing dc output voltage which is theoretically an integer times the AC peak input, for instance, it is possible to get 200 VDC from a 100 Vpeak AC source using a voltage doubler, 300 VDC using a voltage tripler or 400 VDC using a voltage…
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Clamper Circuits – Features & Applications
A clamper circuit or dc restorer is used to clamp a peak of a waveform to a specific DC level compared with a capacitive coupled signal which swings about its average DC level (normally 0 V). If the diode is removed from the clamper, it defaults to a simple coupling capacitor – that is, no…
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Clipper Circuits – Features & Applications
A clipper also referred to as a limiter is a circuit which removes the peak of a waveform. A clipper consists of diodes, resistors and sometimes DC sources to clip or limit the output to a certain level. The input-output characteristics of clipper circuits are typically similar to those of the forward-biased and reverse-biased diode…
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PIN Diode – Features & Applications
PIN diode is characterized by fast low capacitance switching. A PIN diode is fabricated in a similar fashion to a silicon switching diode with an intrinsic region added between the PN junction layers. This generates a thicker depletion region, the insulating layer at the junction of a reverse biased diode. This results in lower capacitance…
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Diode & Filter Applications in Amplitude Modulation (AM) Detection Circuits
The operation of a typical AM audio frequency signal is illustrated in the Figure 1.0 where vin is the modulated signal that is shown Figure 1.1. A typical amplitude modulated signal that is fed into the detector circuit: The diode removes the lower envelope and the upper envelope is illustrated below: The capacitor C2 and…
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Unijunction Transistor Features and Operation
The unijunction transistor (UJT) is a three terminal, single-junction device which exhibits negative resistance and switching characteristics totally unlike those of conventional bipolar transistors. The UJT consists of a bar of n-type having ohmic contacts designated Base 1 (B1) and Base 2 (B2) on either side of a single PN junction designated the emitter. An…
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The Varactor Diode
The varactor also termed to as varicap, is a diode that behaves like a variable capacitor, with the PN junction working like the dielectric and plates of a common capacitor. Because of this, the symbol of the varactor is as shown below: A varactor diode employs a PN junction in reverse bias and has a…
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DC Motor Power Op-amp Speed Controller
Let’s consider the functional diagram below: The D/A converter outputs a voltage directly related to the potentiometer position. However, the D/A converter’s output current is limited and not enough to drive a motor. A power operational amplifier (op-amp) circuit, configured as a noninverting amplifier can drive the motor at the higher currents required. In effect,…