Found in an Electronics Now from the 90s, this circuit uses components that are still common. The LM3900 is a transconductance operational amplifier.
November 2016 - Mouser Electronics is selling the entry circuit for Analog Devices AD8232 and...
This circuit makes use of an unusual Analog Devices component today. The circuit is from a 90's...
This circuit was obtained in an old Elektor and can be adapted to use white power LEDs. The...