This configuration similar to many of this site was found in 1965 General Electric documentation. Modern equivalent transistors can be used. LEDs can be used.
This circuit is for cars with old contact breaker and a 6 V battery. The circuit is from a Radio...
This volume compressor uses unusual components today. The circuit was found in documentation from...
This Intersil circuit was found in a 1980s documentation. Operational are of the time, but current...