The circuit shown is from old English documentation and can be made with BC548 transistors for low power ones. The 2N3055 must be mounted on a heat radiator.
This circuit was found in an American documentation from the 80's. The components are from that...
The circuit shown is from the Texas Instruments optoelectronics manual. It is intended for audio...
This circuit drive an LED with constant current determined by the values of the resistors of 10...