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.
This SCR circuit activates a buzzer when triggered. The circuit is from a Popular Electronics from...
This circuit is used for incandescent lamps and other resistive loads up to 3A using the TIC206. This...
This circuit is from 1995 documentation, but can be easily assembled today, as the components used are...