Bilateral current source 2 (CB20819E)

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

Light Activated Switch (CB3971E)
We find this circuit in a 1970 publication. Transistors can be replaced by current equivalents and LDR is...
Common collector stage (CB9062E)
Featuring low output impedance and high input impedance, this configuration was found in a 1980s...
Alarm with lock (CB8964E)
Found in a 1980s American documentation, this circuit can use a SCR and a general-purpose transistor....