NOR gate with the 7400 (CB22406E)

The configuration below shows how to use the 7400 as a NOR function. The circuit is TTL and must be powered with 5V.

Modem and fax protector (CB8191E)
This circuit is from an old Electroics Now. Its purpose is to protect the fax and modem lines of...
Timer up to 25 Hours (CB4661E)
We found this circuit in a 1994 publication. It makes use of a divider for 16 384 CMOS type 4060. By...
Freeze Alarm (CB14454E)
The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for...