This circuit has an automatic dynamic gain control in a range of 6 dB to 40 dB. We found it in documentation from the 90s. The bipolar transistor is a general purpose type.
The CK722 transistor used in this circuit is one of the first commercial types in the world. The...
This automatic dimmer for incandescent lamps was found in a European publication from the 1980s. The...
This traditional doubler configuration with the 555 can be found in other articles on the author’s site....