This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is 1000 M ohm.
This TTL module can be used in counter and many of them can be cascaded to counts up to 99, 999,...
This circuit was obtained in an American publication of 1977. The circuit generates rectangular...
Epson SG 8018 Epson Crystal Programmable Oscillators Available from Mouser Electronics, these...