This automatic brightness control that uses an LDR as a sensor, was found in American documentation from the 1980s. Resistors in series with LEDs depend on the desired current.
This unity gain circuit was found in the February 1995 Electronics Now magazine. The frequency is 10 kHz,...
Found in a 1967 Electronic Design, this transistorized circuit compresses and then expands a pulse....
This TTL pulse stretcher or stretcher was found in a 90's EDN. The time constant R x C1 determines...