Found in a 1964 Electronic Design this transistor limits signal amplitude to a load. The output is limited to 0.2 V using germanium diodes.
Found in American documentation from the 90s, this configuration detects the direction of rotation...
Circuits similar to this can be found in this section. This is from 1967 General Electric...
This circuit uses two transistors and can be powered by just two small batteries. The frequency is given...