Current indicator (CB22132E)

In this circuit the voltage across the LED is limited by the diodes. The maximum current also depends on the resistor.

Instrumentation Amplifier (CB14497E)
There are several manufacturers of the integrated circuit used and it also admits equivalents. The circuit...
DC Regulated DC Converter (CB6099E)
This circuit was found in Siliconix documentation from the 1980s. Equivalent operational...
Power supply with solar panel (CB21022E)
This circuit was found in a Maxim documentation from the 90s. It is valid for the lower income types...