Found in an Electronics Now from the 90s, this circuit uses components that are still common. The LM3900 is a transconductance operational amplifier.
We found this circuit in an old documentation from the 70s. The text is the original one of the...
The circuit shown in figure is suggested by Maxim in an application note. The operational...
We found this amplifier in a 1990 documentation. The transistors are common, having been made...