This circuit from the 80's makes use of two transconductance operationals of the time. Modern equivalents can be used. The circuit does not need to be powered by a symmetrical source.
June 2017 - Mouser Electronics has a broad line of Cree products for use in horticulture, such as...
Based on common operational amplifiers, this circuit was found in Texas Instruments documentation. The power...
This is an old circuit with a feature that most modern oscilloscopes have. We found it in a Radio...