This CMOS circuit was found in a Popular Electronics from the 80's. The circuit consists of a counter that has its output activated when the selected key combination is pressed.
We found this antenna amplifier or Booster circuit in an Electronics Now from the 90s. The circuit...
In the figure we have 3 oscillators with logic gates that can be triggered by external logic...
This amplifier, common in 1986, uses a hybrid integrated circuit that can offer some difficulty to obtain...