The digital multimeter (DMM) is an essential tool in every electronic enthusiasts arsenal.

**SparkFun How to use a Multimeter –** [Link]

Dave explains why some designs have electrolytic capacitors connected in parallel. The answer is more in-depth than you might think.

9 reasons are given and explained, and then some thermal camera fun on the bench.

**EEVblog #742 – Why Electrolytic Capacitors Are Connected In Parallel –** [Link]

Using Part-Sim we can verify the response of this RL circuit, and our calculations for the initial, final, and the transition between those conditions. While analyzing this circuit’s response on paper and in Part-Sim, we must use the initial conditions (time and V) and component values. In Part-Sim setting up the switch is the hardest part; with the simulation requiring set up of a voltage controlled switch and AC source with a pulse to get the correct behavior in the circuit. Web based Part-Sim allows you to simulate and verify your calculations any time.

**Response of a 1st order RL circuit – **[Link]

The Chebyshev filter features a steep roll-off, but has ripple in the pass band, so it is not suited for audio signal use, where a flat response is ideal. The roll off is so fast that the common definition for cut-off frequency does not work for Chebyshev filters. For this type of filter the cutoff is defined as the frequency at which the response falls below the ripple band. This filter is good for removing harmonics and intermodulation in RF applications.

**1kHz Chebyshev Filter –** [Link]

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]

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]

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

[via]

**Sine wave oscillator using LM741 –** [Link]

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]

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]

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]