This circuit was found in documentation from the 90s. The operational amplifier admits an equivalent. The circuit has frequency ranges up to 5kHz determined by R1.
Found in a 1980s publication, this circuit uses an operational amplifier from that time. The...
This circuit was published in an Italian magazine Radio Elettronica in February 1976. The...
This constant current circuit was found in the October 1993 Electronics Now magazine. The current can...