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Posts Tagged ‘op-amp’

DIY ECG with 1 op-amp

Monday, August 8th, 2016

A DIY ECG made from single op-amp (LM741) and 5 resistors by Scott Harden: I made surprisingly good ECG from a single op-amp and 5 resistors! An ECG (electrocardiograph, sometimes called EKG) is a graph of the electrical potential your heart produces as it beats. Seven years ago I posted...

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Posted in DIY | 1 Comment »

Single OpAmp window comparators

Thursday, December 31st, 2015

In this video Craig shows how to build a window comparator with a single Op-Amp: A recent question on the Electrical Engineering Stack Exchange site got me thinking about some interesting window comparator circuits. Here’s how to detect three different input voltage levels with just one op-amp! More info at Analog...

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Posted in how-to | No Comments »

DIY model train controller project

Tuesday, October 6th, 2015

Ron Hoffman over at Gadgetronicx has written up an article on his DIY model train controller project: Model trains are fun toys which every one of us used to play with in our childhood. Many sophisticated and attractive model trains are available in the market now a days yet the basic principle...

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App note: Does your op amp oscillate?

Sunday, January 11th, 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....

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Posted in app notes | 1 Comment »

Visualizing comparator and Op Amp hysteresis

Monday, December 1st, 2014

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...

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Posted in testing | 2 Comments »

An op-amp based Electret Condenser Microphone Preamp for microcontrollers

Tuesday, November 18th, 2014

Davide Gironi writes: This is an op-amp Electret Condenser Microphone Preamp board design for the use with microcontrollers ADC. For the NPN version of this board, an for more information about microcontroller ADC and microphone input, please refer to this page The proposed circuit is just a revision of a pretty...

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Posted in hacks | No Comments »

Op-Amp based linear regulators

Tuesday, August 12th, 2014

Warren Young of Tangentsoft writes: Experienced audio DIYers are familiar with monolithic linear regulators like the 78xx series and the LM317. Here’s a simplified block diagram of a standard linear regulator, from National Semiconductor’s Application Note 1148 Let’s see... We have an op-amp, a couple of transistors, a voltage reference, and...

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Posted in components, DIY | No Comments »

A single-supply Op-Amp circuit collection

Saturday, July 12th, 2014

An application note from Texas Instruments, A single-supply Op-Amp circuit collection (PDF!): There have been many excellent collections of op-amp circuits in the past, but all of them focus exclusively on split-supply circuits. Many times, the designer who has to operate a circuit from a single supply does not know how...

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Posted in app notes | 2 Comments »

App note: Biasing and decoupling op amps in single supply applications

Sunday, December 1st, 2013

Op amps needs dual supply in order to get a full output swing from its input fed signal, here's a good app note from Analog Devices on powering op amps using only a single supply. Battery-powered op amp applications such as those found in automotive and marine equipment have only...

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Stability 101: Loop gain in operational amplifiers

Saturday, March 9th, 2013

[embed]http://www.youtube.com/watch?v=oOsltCa7qBo[/embed] This video by Analog Devices’ Matt Duff discusses the key term, loop gain, in determining whether an operational amplifier circuit is stable.

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Posted in app notes | 2 Comments »

Noise of a Non-inverting Operational Amplifier Circuit

Saturday, February 23rd, 2013

[embed]http://www.youtube.com/watch?v=W0vfALQ_n54[/embed] This video discusses the total noise of a non-inverting Operational Amplifier (Op Amp) circuit by Analog Devices' Matt Duff.

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SPICEing Op Amp Stability

Wednesday, January 2nd, 2013

Drone writes: Here is a nice little app-note that describes a quick test for op-amp stability using SPICE. (Actually the technique might be useful on the bench as well.) The approach involves applying a step directly to the op-amp input pin and observing the step response. The Author points out...

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Posted in app notes | 1 Comment »

App note: Driving capacitive loads with op amps

Saturday, April 28th, 2012

How to drive capacitive loads with op amps. Operational  amplifiers that drive large capacitive loads can have problems like oscillation and peaking. This article describes how to anticipate and limit theses problems: Other problems include: reduced bandwidth, lower output slew rate, and higher power consumption. This application note explains why...

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App note: Op-amp based DIY linear voltage regulators

Saturday, April 21st, 2012

This is not really an app note, but more of a tutorial on DIY op-amp based linear regulators. The article describes the basics of op-amp regulator, and includes schematics and in-depth explanations of how the various circuits work. This article follows the history of a popular series of DIY linear...

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Posted in app notes | No Comments »

App note: An applications guide for operational amplifiers

Saturday, February 4th, 2012

Here is a application guide from Texas Instruments is an overview of operational amplifier-related circuits, theory, and formulas. Inverting amplifiers, buffers, analog adders, filters, and many more are covered. The general utility of the operational amplifier is derived from the fact that it is intended for use in a feedback...

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Posted in app notes | 3 Comments »

App note: Op-amp/comparator module for dsPIC

Sunday, January 1st, 2012

Some dsPIC33E and PIC24E microcontrollers have an comparator module that can function as an op-amp [PDF]. The module can be used as a simple non-inverting amplifier by adding two external resistors, no external op-amp chip needed. The output can be read internally by the ADC module, or routed externally to...

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Posted in app notes | 9 Comments »

Simple USB DIY Li-ion battery charger circuit

Wednesday, October 5th, 2011

arup shared his USB DIY Li-ion battery charger circuit in the project log forum. The circuit uses both op-amps of an LM358 to control the charging of a single cell lithium ion battery. Charging automatically stops when the battery is full, and it is possible to charge batteries that have gone...

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Posted in Lithium Ion, project logs | 14 Comments »

TS1001 low power, low voltage op-amp review

Thursday, July 28th, 2011

We have been experimenting with the Touchstone semi TS1001 ultra-low power, low voltage op-amp demo board, and the results are in. For our tests, the board inverting op-amp circuit was powered by a solar cell from a calculator with two 0.5v zener in series. The total supply was about 950mV,...

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Posted in Chips, part review | 3 Comments »

Touchstone TS1001 op-amp demo board unboxing

Wednesday, July 6th, 2011

Touchstone Semi sent a demo board for the record-breaking, low power, low voltage TS1001 op-amp. We covered their design competition earlier. The demo board has a complete support circuit so the parts are ready to evaluate.  It's populated with two TS1001 op-amps, in inverting and non-inverting configurations. Attention component manufacturers:...

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Posted in dev boards, parts | 13 Comments »

Touchstone Semi Coolest Op Amp design competition

Tuesday, May 31st, 2011

Touchtone Semiconductor is a startup company whose products include an op amp known as the TS1001, which they say is the only such component to operate on 0.8 V and 0.6uA. They've announced a Coolest Op Amp design competition for developers who incorporate the TS1001 into their designs. See the...

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Posted in parts | 1 Comment »

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