So i wanted to create a counter that counts from 59 down to 0 using 4510 IC component, so i created simulation in Proteus software.
This is what i came up with:
This circuit works perfectly fine when there's no feedback from outputs of lower 4510 to it's PE input. As you can see, feedback circuits consist of one 4 input NOR gate and one OR gate which is supposed to enable PE input whenever i press button connected to OR gate input or, when combination of four zeros appears at the output of 4519 IC.
However, it happens so that, instead of reseting at zero state at the output, it resets when i have combination 0100 at the lower and 0000 at the upper 4510 IC, so it resets in the moment when i am supposed to go from 0100 (4) to 0011 (3) so i believe that the problem is with delay periods of logic gates or something (i am not quite sure if this is the case), and i don't know how do i need to enhance this circuit in order to make it work properly, as it is supposed to. Any help appreciated!