This current boosting circuit uses an op-amp and 3 transistors. The current depends on Q1. The circuit is from the 1995 Encyclopedia of Electronic Circuits Volume 5.
The basis of this project is a three-position lever switch or similar. When the switch is in the...
This physical line servo control uses components that are not currently common. The circuit is from...
This circuit was found in a Popular Electronics from the 90's. The power transistors must be...