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 a Radio Electronics. The circuit can be seen elsewhere on this site. The...
Found in old American documentation, this filter has a 8 dB per octave attenuation. The formulas for...
The circuit presented is from the Linear Applications Handbook of the National Semiconductor of...