Using the 555 and 4020, this timer was found in the July 1994 Radio Electronics magazine. The relay is voltage-dependent, and the transistor is general purpose.
Using the CMOS 4001 we found this circuit in the October 1974 Radio Electronics magazine. The...
One 4018 is used to divide the frequency of a digital signal by ten as shown here. The maximum...
This 90's project shows how to use an old cassette recorder to practice telegraphy. In position A of the...