7 Segment Control with 74series digital logic

I haven’t play with digital logic all that much so forgive me if I miss some things.

For my power supply I want to add the ability to control it digitally from a computer let alone a custom 7 segment display. Now I really do not want to use a AVR for this so I’m trying to go a bit old school and use some 74 series logic to control the display.

I’m using a Anode type 7 segment with a 7446 encoder. To control the encoder I am using a 74192 4-bit up/down counter. With two push buttons for the up and down selections it will let me select from 0-9 and 9-0. However there is a crap load of bounce. I tried tossing on a 7404 Hex inverter to deplete the bounce but has no effect. I tried a schmitt-trigger setup and it works better but when I added the count up switch for some odd reason it skips the number 9. When the count hits 9 it quick pops up then moves to zero. Also when counting down it counts by 2s, this is very odd.

In all it was simple but still a bit touchy. Use a 10K resistor to pull up the signal with a cap going from the voltage side of the switch to ground. Works very well with tactile switches.


It may look a bit mess but I’m doing my best to get use to the program for creating the schematics.


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