I found this schematic from this site
telephone number display circuit diagram
And it seems to have just what I need: a keypad display without using microcontrollers. Now I need only the keypad display. My basic idea is to remove the whole CM8870PI and the logic gates near it, put push button switches representing digits 0-9, and then use a 74- BCD encoder, and hook it to the ABCD and that's it. I just need to clarify some questions regarding the conversion process
1) Will my idea work?
2) Does pin 15 of the CM8870PI hold some value? If it does, can I convert it?
3) I can't see IC11 and IC12. What is the author talking about?
4) Are there any 74xx equivalents for CD4017BE, CD4508 and CD4511? I think 7447 can replace CD4511, but I'm not sure
There are still many other questions that I might ask, but this just for now. Any help would be appreciated. Thanks
telephone number display circuit diagram
And it seems to have just what I need: a keypad display without using microcontrollers. Now I need only the keypad display. My basic idea is to remove the whole CM8870PI and the logic gates near it, put push button switches representing digits 0-9, and then use a 74- BCD encoder, and hook it to the ABCD and that's it. I just need to clarify some questions regarding the conversion process
1) Will my idea work?
2) Does pin 15 of the CM8870PI hold some value? If it does, can I convert it?
3) I can't see IC11 and IC12. What is the author talking about?
4) Are there any 74xx equivalents for CD4017BE, CD4508 and CD4511? I think 7447 can replace CD4511, but I'm not sure
There are still many other questions that I might ask, but this just for now. Any help would be appreciated. Thanks