Equivalent transistors can be used in this circuit for automotive applications in the 1980s. The frequency is given by the capacitor and the current of the lamp depends on the LM195 transistor.
This application is from a circuit manual from the 90s and only works with incandescent lamps. The triac...
This circuit was found in an American magazine in 1978. It activates a relay when the speed of a...
This circuit is from 1976 documentation, but it can be assembled with more modern transistors like...