Author: John Mulindi
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Basic Facts about 4-20 mA current loop in Process Instrumentation
The 4-20 mA current loop, like the one shown in the diagram below is a typical way of transmitting sensor information in most of industrial process monitoring applications. A sensor in this case is a device used to measure the physical parameters such as liquid flow rates, temperature, pressure, speed, and so on. The 4-20…
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What are Supercapacitors?
Supercapacitors (double-layer or ultracapacitors) are devices that store extremely large amounts of charge (from 0.022 F to 55 F) much more than a normal capacitor. Their level of energy storage approaches around 1/10 that of a low-density battery. But, unlike a battery, the power output can be 10 times greater (a handy feature in high-current…
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Digital Voltmeters: Basic Features, Operation & Applications
The digital voltmeter (DVM) displays measurement of ac or dc voltages as discrete numbers instead of a pointer deflection on a continuous scale as in analog instruments. A digital voltmeter basically consists of an analog-to-digital converter, a set of seven-segment numerical displays and the necessary BCD-to-seven-segment drivers. A digital voltmeter is a versatile and accurate…
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Equipment Grounding vs. System Grounding
Grounding or earthing an electrical system is the process of connecting all metalwork/frame of electrical equipment i.e. the non-current carrying part or some electrical component of the system such as the neutral point in a star-connected system, one conductor of the secondary of a transformer, and so forth to the main body of earth. An…
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Sweep Frequency Generator: Function, Features & Applications
Function & Features of a Sweep Frequency Generator A special type of signal generator which generates a sinusoidal output whose frequency is automatically varied or swept between two chosen frequencies is referred to as sweep frequency generator. One complete cycle of the frequency variation is termed as a sweep. The rate at which the frequency…
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Switchgear Terminology & IEC Standards
Switchgear generally refers to the switching devices and their combinations, with the related control, measuring, protective and regulating equipment. The switchgear equipment basic purpose is switching and interrupting currents either under normal or abnormal operating conditions. Modern power systems, power lines and other apparatus operate at high voltages and carry large currents. When a short…
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Electron/Vacuum Tubes vs. Semiconductor Devices
Electronic circuitry has undergone tremendous changes since the advancement of a triode, a type of electron tube that consists of three elements namely filament, grid and plate. In a triode, the amount of current from the cathode to the plate (i.e. controlled current is a function of both the grid to cathode voltage (the controlling…
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Fault Protection & Diagnostics in Power ICs using Temperature Sensors
Fault conditions sensing for example, the detection of a short circuit is an integral part of many smart power integrated circuits (ICs)/power ICs. The ability to get temperature sensors in the semiconductor process provides protection and diagnostics as part of the features of these devices. The main function of the power IC is to provide…
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Voltage-Controlled Attenuator: Function, Features & Application
Function of a Voltage-Controlled Attenuator The function of a voltage-controlled attenuator is to produce an output signal vo(t) that is a variable fraction of the ac input signal vin(t). The process of reduction of the amplitude of a signal is called attenuation. Features of a Voltage-Controlled Attenuator Let’s consider a circuit of a voltage-controlled attenuator…
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Microwave Active Devices: Types, Features & Operation
Generally microwave devices can be categorized as either passive components or active components. We have already talked about microwave passive components in this other article. This article focuses on microwave active devices. They may be classified into two types: low-power solid-state devices and high-power vacuum tube devices. Communications involving the gigahertz bandwidths cannot employ conventional…