This circuit for cars with fans was found in Silicon Chips documentation from the 90s. It is used to activate the fan when the radiator water temperature rises.
This circuit provides a constant current of 1 mA, stabilized by an LED, which can be equivalent to that...
This receiver for the mid-wave band was found in a documentation from the 60's. The transistors are made...
This circuit converts a positive CMOS supply voltage to a negative one. We found it in a 90s...