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.
We found this circuit in a Popular Electronics of the 90s. The circuit still uses light bulbs, but...
This circuit is from Linear Technology 2005 documentation. The circuit is based on company...
The integrated circuit used in this power supply is no longer very common in power supplies today....