Reverse polarity protection 2 (CB22140E)

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

Continuity tester (CB9326E)
This circuit was obtained in an Electronics Now from the 90s. The circuit uses operational...
Physiotherapy Ultrasound (CB16841E)
This circuit operates at a frequency around 1 MHz, having been found in a technical documentation from...
Integrated Transmitter without Coil (CB14821E)
The TAA131 used in this circuit is not very easy to find today, but an equivalent low power audio...