Solid state relay (CB8518E)

This circuit was found in a 90s Popular Electronics. Both the coupler and the MOSFET can be of any type.

15 V x 1 A power supply with Shutdown LM340 (CB14264E)
We found this configuration in the Linear Applications Handbook of the National Semiconductor of...
AC Amplifier TL081 (CB15544E)
This circuit is an application for an operational amplifier with field effect transistors from...
Automatic Activating Alarm (CB4778E)
This circuit was found in an old Radio Electronics, but can still be assembled as the components are...