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28 Mar 2015

The most often requested video! In this tutorial Dave explains what Operational Amplifiers (OpAmps) are and how they work. The concepts of negative feedback, open loop gain, virtual grounds and opamp action. The comparator, the buffer, the inverting and non-inverting amplifiers, the differential amplifier, and the integrator circuit configurations are also explained.
Then a practical breadboard circuit to demonstrate a virtual ground and the effect of voltage rail limitations.

OpAmps Tutorial – What is an Operational Amplifier? - [Link]

26 Mar 2015


In semiconductor and electronics industry, a diode is a widely used discrete component. It is a significant element in many electronic circuits and applications ranging from low power signal circuits to power rectification. Based on the functions and ratings, there are different types of diodes. However, all semiconductor diodes contain a PN junction to perform their basic operation.

Diodes – Types and Applications - [Link]

11 Mar 2015


Sine wave oscillator using LM741, a project by A.M. Bhatt of EngineersGarage:

There are different kinds of Sine wave oscillators based on the components used or based on the output frequency that they generate
1. Based on components means if they produce oscillation using resistors (R) and capacitors (C) then they are called RC oscillators and if they use inductor (L) and capacitor (C) then they are termed as LC oscillators
2. Based on output frequency means if they generate frequency in audio range (20 Hz – 20 KHz) then they are Audio Frequency (AF) oscillators. If they generate frequency in low range (100 – 200 KHz) then they are called Low Frequency (LF) oscillators and last, if they generate frequency in high range (in MHz or GHz) then they are termed as High frequency (HF) or Radio Frequency (RF) oscillators.

I am presenting here two such sine-wave oscillators that uses RC components to generate oscillations and they can generate frequency in AF range as well as RF range. The two oscillators are
1. RC phase shift oscillator
2. Wien bridge oscillator


Sine wave oscillator using LM741 - [Link]

10 Mar 2015


Determine the values of the node voltages va and vb for the circuit shown in the figure. The first node equation: the voltage source voltage is related to the node voltages by vb- va = 12  =>  vb = va + 12. To write the second node equation, we must decide what to do about the voltage source current.  KCL can be applied to the problem to generate the 2nd node equation : va/6 + vb/3 = -2. In summary, the node equations are vb – va = 12 and va/6 + vb/3 = -2. Solving the node equations gives va = 12 V; and vb = 0V.

Supernodes - [Link]

6 Mar 2015


by Einar Abell @ edn.com:

This Design Idea gives two versions of an indicator light that changes from green to red as a battery discharges. There are many circuits that do this sort of thing, but all the ones I have seen are too complex and costly for my taste. This DI shows a method that uses an absolute minimum of low cost parts: a dual-color LED and four other parts.

Voltage indicator transitions between colours - [Link]

9 Feb 2015

Back to basics introduction to the differential amplifier, aka the diff-pair, long-tailed pair, emitter coupled pair, etc. The basic operation of the circuit is presented, along with a simple mechanical simulation. Also, how the addition of current sources and mirrors can be used to address some of the performance issues, and begin to form the rudimentary beginnings of an op amp. This is the follow-up video from “teaser” video published earlier.

Back to Basics: the differential amplifier, aka long-tailed pair, diff-pair - [Link]

12 Jan 2015


All about Op Amp stability app note from Linear Technology.

Well, it shouldn’t. We analog designers take great pains to make our amplifiers stable when we design them, but there are many situations that cause them to oscillate in the real world. Various types of loads can make them sing. Improperly designed feedback networks can cause instability. Insufficient supply bypassing can offend. Finally, inputs and outputs can oscillate by themselves as one-port systems. This article will address common causes of oscillation and their remedies.

App note: Does your op amp oscillate? - [Link]

6 Jan 2015


by Ilija Uzelac @ edn.com:

This Design Idea presents a simple, proven, reliable, and robust method for charging large capacitor banks, using a series connection of power MOSFETs to raise the breakdown voltage over that of an individual MOSFET.

When a power supply drives a large capacitive load, inrush current, if not limited, can reach tens or hundreds of amps for a high voltage power supply. In general, maximal ratings of a power supply could be transiently exceeded by many times, but this is generally acceptable when the transient lasts a few AC-line cycles. This is typical for load capacitances up to a couple of hundred microfarads, but for load capacitances in thousands of microfarads, an inrush current limiter is a must.

Series-connected MOSFETs increase voltage & power handling - [Link]

29 Dec 2014


An app note (PDF) from KEMET on coupling two high lifetime devices: LEDs and Supercapacitors.

Light emitting diodes, or LEDs, have come to prominence in recent years in conventional lighting applications including flash lights, street lamps, traffic lights and emergency lighting. Their advantages over incandescent and compact fluorescent light sources include greater robustness, higher energy efficiency and a longer lifetime. Due to the constantly falling prices of LEDs, they are also now becoming more economical in the long term than traditional light sources.
Supercapacitors are high lifetime, high power devices that store relatively little energy compared to a battery. The low power requirements of LEDs means that a reasonably sized supercapacitor power source can still provide several hours of lighting on a single charge, while the high lifetime and low-temperature performance advantage over batteries is maintained. The emergence of 3.0 V supercapacitor cells as well as hybrids only strengthens the case for their use in LED applications due to the higher amount of energy stored in these new supercapacitor types. Supercapacitors are also free of lead, mercury, and cadmium, which eases any environmental concerns that may arise over the course of their long term use and eventual disposal/recycling.


App note: LED lighting and supercapacitors - [Link]

17 Dec 2014

by Afrotechmods @ youtube.com

A beginner’s guide to different battery chemistries and how to choose the right battery for your project.

How to choose a battery: A battery chemistry tutorial - [Link]





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