This circuit uses a General Electric coupler from the time of the publication in the 1980s. Equivalent SCR can be used.
We found this interesting timer circuit or CMOS timer in a 1988 publication. The circuit is still...
This circuit found in Radio Electronics can be used in games to produce a random pulse train. The...
We found this amplifier with high input impedance and low capacitance, using FET, in a...