This conventional filter circuit is from American documentation from the 1990s. The operational amplifier admits an equivalent and the power supply must be symmetrical.
In the figure we have an improved method of varying the voltage of a 7812 regulator. The circuit is...
This amplifier operates with a current amplifier for audio distribution lines. The power MOSFET can...
This circuit was found in Popular Electronics from 1992. The circuit has steps determined by...