This tutorial discusses some general rules of thumb that make it easy to understand and analyze the operation of most opamp circuits. It presents some ideal properties of opamps, and discusses how negative feedback generally causes the input voltage difference to be equal to zero (input voltages are made equal by the action of negative feedback). In other words, the output will do whatever it can to make the input voltages equal. Applying this simple fact makes it easy to analyze most opamp circuits.
Basics of Opamp circuits – a tutorial on how to understand most opamp circuits - [Link]
The LT6015 is a single Over-the-Top operational amplifier with outstanding precision over a 0V to 76V input common-mode voltage range. It incorporates multiple built in fault tolerant features, resulting in no-compromise performance over wide operating supply and temperature ranges. Over-the-Top inputs provide true operation well beyond the V rail. The LT6015 functions normally with its inputs up to 76V above V-, independent of whether V+ is 3V or 50V. Input offset voltage is 80μV max, input bias current is 5nA and low frequency noise is 0.5μVP-P, making the LT6015 suitable for a wide range of precision industrial, automotive and instrumentation applications. Fault protection modes guard against negative transients, reverse battery and other conditions. The LT6015 is available in a 5-lead SOT-23 package and is fully specified over -40°C to 85°C, -40°C to 125°C, and -55°C to 150°C temperature ranges.
LT6015 – 3.2MHz, 0.8V/μs Low Power, Over-The-Top Precision Op Amps - [Link]
This article describes how to use infra-red (IR) sensor with Arduino or with a simple OPAMP comparator. Lee Zhi Xian writes:
What is infra-red (IR)? Infra-red is an electromagnetic wave who wavelength is between 0.75 microns to 1000 microns (1 micron = 1µm). Since infra-red is out of visible light range, we can’t really see IR with naked eye. However, there is a method to “see” IR which will be shown later on. Some of the infra-red applications includes night vision, hyperspectral imaging, and communications. We also use IR daily in our TV remote or any device remote.
IR transmitter and receiver can be obtained at low price. Their shape is looks exactly the same as LED. To distinguish between transmitter and receiver, the transmitter always come in clear LED while receiver is black in colour. Other than that, there is also receiver that is used to pick up specific frequency IR, 38kHz. For your information, 38kHz frequency IR is commonly used in remote control.
How to use infra-red (IR) sensor with Arduino - [Link]
Active analog filters can be found in almost every electronic circuit. Audio systems use filters for frequency-band limiting and equalization. Designers of communication systems use filters for tuning specific frequencies and eliminating others. To attenuate high-frequency signals, every data acquisition system has either an anti-aliasing (low-pass) filter before the analog-to-digital converter (ADC) or an anti-imaging (low-pass) filter after the digital-to-analog converter (DAC). This analog filtering can also remove higher-frequency noise superimposed on the signal before it reaches the ADC or after it leaves the DAC. If an input signal to an ADC is beyond half of the converter’s sampling frequency, the magnitude of that signal is converted reliably; but the frequency is modified as it aliases back into the digital output.
Designing active analog filters in minutes - [Link]
All about opamp input bias currents. Dave goes through the theory, and then does some practical measurements and tweaking.
Opamp Input Bias Current - [Link]
Designing and measuring basic and precision opamp peak detector circuits.
Peak Detector Circuit - [Link]
Bruce Trump writes:
Slewing behavior of op amps is often misunderstood. It’s a meaty topic so let’s sort it out.
The input circuitry of an op amp circuit generally has a very small voltage between the inputs—ideally zero, right? But a sudden change in the input signal temporarily drives the feedback loop out of balance creating a differential error voltage between the op amp inputs. This causes the output to race off to correct the error. The larger the error, the faster it goes… that is until the differential input voltage is large enough to drive the op amp into slewing.
Slew Rate – the op amp speed limit - [Link]
Have you ever wanted to take a standard voltage op-amp and turn it into a high voltage output circuit? Here is a technique that requires some shunt regulators to power the chip and some current limiting transistor circuitry for the output. This example should work upto +/- 120V.
Make an Op-Amp High-Voltage Output Circuit - [Link]
This is a great video of Alan Wolke talking about op-amp power supply options. He explains the differences when using op-amps on a single supply, a split (or bipolar) supply and virtual ground.
This video discusses the power supply considerations for op amps. It talks about split or dual power supply and single supply operation, and why the op amp often doesn’t care which you use! It shows how traditional op amps designed for split supply operation can be used in single supply applications. The most important consideration generally is taking care of where the input and output voltages are with respect to the supply rails. The input voltage and output voltage range specifications are examined in a datasheet. The operation of a op amp in a single supply application is examined on an oscilloscope. This operation is compared to a modern rail-to-rail op amp in the same circuit.
Op Amp Power Supplies: Split, Single, and Virtual Ground Designs - [Link]
Kerry Wong shows how to make an adapter circuit for measuring very low voltages with a multimeter.
A typical 3 ½ or 4 ½ multimeter can measure voltage in the low mV range and current in the low mA range. Voltage measurement in the µV range and current measurement in the nA range are typically only available in the more expensive lab bench multimeters. In this post, I will show you a simple adapter circuit that can be used for precision voltage measurement down to the µV range. Using this circuit along with the current adapter circuit I discussed earlier you will be able to perform most of the low level measurements with a 3 ½ meter.
Precision Voltage Adapter For Low Voltage Measurement - [Link]