The circuit shown is from Motorola's 1990 Linear Databook. Components are not currently common. An equivalent can be used for the transistor.
This circuit of a 1991 PE Hobbyst Handbook allows the brightness of the incandescent lamp to be...
This circuit is from the old RCA transistors manual of 1964. The transistor can be the BC558 and...
Originally this circuit is from an English magazine, but I found it in Argentina's Radio Chassis...