Some months ago I started a project with a friend, but unfortunately we bit more than we could chew and now we 're over our heads.
The project consists of 30 or so 74XX(X) IC's (don't ask me why I chose 74 series, it wasn't my choice and was a prerequisite) and a 555.
We designed the whole circuit in Multisim, ran simulations, everything worked fine. So I ordered the dual layer PCB and soldered the components on it.
From that point, all hell broke loose. Erratic behaviour, different results from the same starting point, and so on. I even tried to remove the 555 and use and external manual clock, but the 555 circuitry (caps and resistors) kept on alternating the clock level even if I din't push the manual clock button.
One thing that I thought about (and hurts me to realise it now) is that I haven't used ANY (oh god, why?) debouncing capacitor. How serious a crime is this? Does it explain this kind of behaviour?
I could post a schematic in multisim file form or in an image (a large one though), but I doubt it will be of any help. If someone has a loooot of free time to try to understand what I have built, I would be happy to post a copy.
Thanks in advance!
The project consists of 30 or so 74XX(X) IC's (don't ask me why I chose 74 series, it wasn't my choice and was a prerequisite) and a 555.
We designed the whole circuit in Multisim, ran simulations, everything worked fine. So I ordered the dual layer PCB and soldered the components on it.
From that point, all hell broke loose. Erratic behaviour, different results from the same starting point, and so on. I even tried to remove the 555 and use and external manual clock, but the 555 circuitry (caps and resistors) kept on alternating the clock level even if I din't push the manual clock button.
One thing that I thought about (and hurts me to realise it now) is that I haven't used ANY (oh god, why?) debouncing capacitor. How serious a crime is this? Does it explain this kind of behaviour?
I could post a schematic in multisim file form or in an image (a large one though), but I doubt it will be of any help. If someone has a loooot of free time to try to understand what I have built, I would be happy to post a copy.
Thanks in advance!