Temperature controller LM3911 (CB21281E)

This circuit is from a Popular Electronics from the 90's. The circuit provides an output for a control stage.

SCR Passage Alarm (CB13378E)
We found this circuit in an old documentation from the 70s. The sensor is an LDR that must be...
2 meters preamplifier (CB20274E)
This circuit with junction field effect transistors was found in documentation from the 1980s. The...
1.2 to 1.4 V Power-Supply (NI025E)
Common general purpose silicon diodes when direct biased provide a voltage fall of about 0.6 to...