Reverse polarity protection 2 (CB22140E)

This circuit has an improvement over the previous one as it also has an LED indicator for correct polarity.

Shaver adapter (CB9953E)
This circuit allows 220 / 240V shavers to be used in the 110V network. The diodes can be general...
Visual dialing indicator (CB9296E)
Used with telephones at the time, this circuit was found in Popular Electronics from the 90s. The...
Fast Logarithmic Converter (CB5104E)
This circuit was obtained from an American 80's documentation. It can be implemented with modern...