Make a Voltage-Controlled Oscillator with Just One Opamp

It is instructive, easy and even fun to play around with the free circuit simulator LTSpice every once in a while. In this video you will first learn how to analyse and understand a simple opamp-based square wave oscillator taken from an “old” datasheet before changing it into a voltage-controlled oscillator (VCO). Building the circuit on a breadboard shows that it really works. The simulations are of course available for downloading to get your own experiments up and running quickly.

A simple voltage-controlled oscillator (VCO) built with just one operational amplifier and a few passive components.

The final instalment of the short series on opamp basics explores some of the more unusual features of operational amplifiers. Another topic is opamps with power outputs.

Even an IC that has clocked up some fifty years on the market is not necessarily hopelessly obsolete. A case in point is that several semiconductor companies are still making the LM386 power operational amplifier, and even now are bringing out new and improved versions.

Many active crossover filters have been published over the years and almost without exception they contain many, and often expensive, components. The filter presented here is a rare and favourable exception as comparatively few components are required of the ‘normal’ type i.e. not accurate to the nth degree and made from unobtainium™.

Operational amplifiers are ubiquitous in electronics, being used in a wide range of applications in all sorts of configurations. There are numerous device families and types available, each with their own strengths and weaknesses. So here we will take a closer look at the details.

High precision op amps enable system designers to create circuits that condition signals (amplify, filter, and buffer) while maintaining the precision of the original signal. When information is contained in very small variations of the signal, it is critical that op amps in the signal path perform their operation while contributing very little DC and AC error. The precision of the total system depends on maintaining the precision of the signal path.

New in the Electronics Design Library is Volume 2 of FOCUS ON: Bob Pease on Analog. With very few exceptions Bob Pease is remembered fondly all over the globe for his analog design expertise as well as his sense of humor. Our esteemed competitors Electronics Design (magazine) shared and spread his wit and knowledge with the electronics community for years with his special column “Pease Porridge.”

When choosing an operational amplifier for an application you already know you will be looking at criteria such as supply rail, slew rate, drift, output voltage swing, gain bandwidth, residual current, noise, etc., your final choice will often be a compromise. It goes without saying we will only be considering small signals so when the application calls for high output voltage and current drive something special is required...

2 sided FR4 PCB that implements a configurable op-amp circuit for single SOT23-5 amplifiers and 0805 passive components and 0.1inch grid pins.