Bilateral current source 2 (CB20819E)

We found this circuit in an American publication from the 1980s. Equivalent modern operational amplifiers can be used.

1 kHz Low Pass Filter LM3900 (CB14188E)
The circuit shown below is from the National Semiconductor's 1994 Linear Applications Handbook. The...
Metronome with the CA3130 (CB12478E)
This metronome was found in a 1979 publication, but it can be assembled more easily with the BC548...
Symmetrical 5 V power supply (CB24712E)
This circuit for a maximum current of 1 A is the most common version that uses the 78 and 7905...