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12 Jan 2015

an_linear_an148

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

DI5473f1

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_kemet_LED_and_supercap

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.

[via]

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]


17 Dec 2014

point-contact-transistor-290

by Jessica MacNeil @ edn.com:

What began as research to improve telephone service became one of the most important inventions in electronics history.

In 1945, AT&T’s research division, Bell Labs, began working on technology to replace vacuum tubes and make long-distance telephone service more reliable. William Shockley organized a solid-state physics group to research semiconductor replacements for vacuum tubes and electromechanical switches.

1st successful test of the transistor, December 16, 1947 - [Link]

2 Dec 2014

setup-600x450

Kerry Wong writes:

Hysteresis can be added to a comparator circuit to improve its stability, especially when the input signal is noisy. In this post, we will examine the hysteresis characteristics of some common comparator and Op Amps using an oscilloscope.
Perhaps the most intuitive way to visualize the hysteresis in a circuit is to plot the input signal (x axis) against the output signal (y axis). So, if we sweep the input voltage we should be able to see the characteristics of the transitioning of the output voltage due to hysteresis.

Visualizing comparator and Op Amp hysteresis - [Link]

22 Nov 2014

by w2aew @ youtube.com:

Today’s “Back to Basics” tutorial topic – why flyback or snubber diodes are used around relay coils when switched or controlled by low power electronics. We’ll talk about how and why dangerously high voltages can be generated from the collapse of the stored magnetic energy in the coil when they’re switched off, and how the diode can protect the low power electronics from being damaged by these high voltages. Some voltage and current measurements are made on an actual circuit to see the real-world effects.

Why diodes are used around relay coils - [Link]

24 Oct 2014

BH Figure 1cx600

 

by Barry Harvey @ edn.com:

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.

Does your op amp oscillate? - [Link]

29 Sep 2014

ap_NXP_an10853

A good beginner app note (PDF) from NXP on protecting ICs from ESD.

Integrated circuits are sensitive to electrostatic discharge (a sudden and short-time flow of currents) and electromagnetic fields (at which they can be source or victim of both of it). This application note shall be understood as an introductive basic description of what electrostatic discharge is, how sensitive devices can be protected against electrostatic discharges, what electromagnetic compatibility means and how electromagnetic sensitivity can be tested.

[via]

App note: ESD and EMC sensitivity of IC - [Link]

22 Sep 2014

by w2aew @ yoututbe.com

Op amp gain-BW product and slew rate limiting are defined, discussed and demonstrated on the bench. This discussion applies to the majority of general purpose op amps on the market – as most op amps are internally compensated with a single dominant pole. High speed op amps, unconditionally stable op amps, non-unity gain stable op amps, high power opamps, etc. may not follow these characteristics because they are often compensated differently in their design. An LM358N is used for the example circuit. Other popular op amps like the LM741, etc. will behave in a similar way. Sometimes the slew rate limit of a device will be the dominant factor in determining the bandwidth, and other times the gain-bandwidth product will determine the resulting frequency response. The video demonstrates why this happens.

Basics of Op Amp Gain Bandwidth Product and Slew Rate Limit - [Link]



 
 
 

 

 

 

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