Charger protection relay (CB26312E)

This circuit was obtained from an Elektor magazine from the 90s. The circuit is to protect batteries while charging.

Notch Filter (CB12169E)
This filter that rejects determines frequency (notch) was found in a Popular Electronics of 1993....
400 MHz RF isolation amplifier (CB8639E)
This circuit operates with frequencies from 0.5 to 400 MHz. We find it in a 90’s NASA...
Transistor dummy load (CB22476E)
This circuit for adjusting sources simulating a load was found in a publication from 1993. The...