This circuit was found in the March 1992 issue of Radio Electronics magazine. The circuit has several adjustments and uses an operational amplifier. Note the supply voltage.
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...