We found this code key or coded keyboard in a publication from the 90s. The circuit uses components that are still common today and is powered by a 12 V voltage according to the relay used.
This circuit was found in a 90s Integrated Circuits Data Book. It interfaces a data line with a...
The basis of this project is an integrated 566 (not to be confused with a 556 which is a double...
Found in Motorola documentation from the 1980s, this circuit employs an integrated device from...