I am building a 12 hour clock the seconds and minutes work fine but when i switch from 7490 to 74190 going into 7447 in 7 seg. the from the same 74190 to7410 and 7476 i am having all kinds of problems
If you give us a schematic we may be able to help. It sound like you have the basics down, which is excellent, but without a major hint we can't really help.
How to upload an attachment:
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Schematics should be .gif or .png format, pictures should be .jpg. .jpg formats will fuzz out schematics, and should not be used for that purpose.
I have a series of templates I use to draw schematics that is free for downloading.