Logic Outputs Problem in 7493 IC

[Moley]

Sorry to jump in. This thread has been bringing back lots of memories of messing around with logic chips over 40 years ago. I've forgotten most of it now but it was fun at the time. My first design was a keypad operated car imobiliser for my Astra GTE.
Did you know there are companies in China such as JLCPCB that will produce PCBs for next to nothing if you can supply a Gerber design file. That would make your life so much easier. For example, 20off 100 x 50mm single sided boards are £9.52 plus delivery. Uk delivery is from £5.60. I know it takes away the fun(!) but it would make your life a lot easier.

 

[pc1966]

Unrelated directly to this thread but maybe of some interest is this transistor data book from 1964, more fo the hundreds of pages of information on how they work and circuit ideas:

https://worldradiohistory.com/BOOKSHELF-ARH/GE-Books/GE-Transistor-Manual-1964.pdf

I guess most of the devices are long-obsolete, but I do see the 1N4148 diode listed at one point which is still around, and I have used a 2N709 transistor many decades ago...

 

[marconi]

pc1966 - the sort of reading material I was weaned on. I have to say, that like many engineers, I was glad when 'electronic functionality' did not have to be designed and built from scratch each time, and instead one could take ics with reliable and repeatable functionality and combine them together to do things.

I love following q12 as he works through his projects, confronts problems head on, analyses them to come up with a fix and then as every good engineer should be able to do actually makes a design himself and tests it to confirm it does indeed work.

 

[_q12x_]

Oh, WOW, VISITORS ! Haha. Im glad to see you guys here.
I read everything you write. I was 100% preocupied with the very problematic construction I am into now, if you remember I complained it didnt work for some very elusive reason and indeed it was VERY strange ! The mistery come only from diodes. I guess, they are special ones... the hell... but I figure it out.
I made a movie about the entire thing, I am also showing the 'stage' when it was giving the error and what kind of error it was, and then in the end of the movie, the working version that is now final. WOW, what a day, I literally worked all day long on it, with almost no breaks. Usually I work with breaks. But amazingly, I didnt get so many and mostly work-work-work. And Im very glad I did. Now I got the working thing. Please watch the video (after I will upload it) and tell me your thoughts what possibly can be the reason for failure. Also I have the first module 1234, that is also having these diodes in that special place- I mention in the video where it is and showing everything clearly what is what there. But that was the thing that puzzled me enormously, why it worked fine with 1234 and here on 5678 didnt. Although I only used them in 56. The 78 were with more (possibly) modern diodes than those sphere ones. Very weird stuff. I like it ! Haha. I am specially pleased that I could used these scrapped components and re-purpose them into something new and practical. Hopefully it will be practical, we'll see. Haha.
Thanks everyone for the kind words and comments. Always a pleasure.
I will post the video soon enough.
PS. Also I bet that @marconi will like very much how I solved the problem ! I like it too, although is not easy, but it is WAY more clear and visible to work with this new board setup/configuration.

 

[_q12x_]

Stripboard - Wikipedia - https://en.wikipedia.org/wiki/Stripboard
what about using stripboard/veroboard or making up your own version of it?

I have both versions. Also from you that you send me, I still have it, un-violated, virgin and shiny. And also I have custom copper board that I made LOOOOOOOooooong time ago. Still have them, also never used them. My idea 100% on them. Only a small one that I used it to death. But after that, I never touch it.
I know exactly what you say... but what Im doing here is partly prototyping(my own customized way of boards), partly finish product(as small as I can possibly make it), partly experimenting(because weird scrapped components). I have to choose what is ---convenient--- to me. Not everything that flies is also good (is a saying in my place).
But I like your way of thinking, you start to get more closer on my direction of thinking and doing things.
A deserved 10+ from me for your direction of thinking. Haha.

 

[_q12x_]

-Voila, enjoy:

 

[Moley]

I've just watched the video and there's one thing I can't work out - you are either a genius or totally insane

 

[_q12x_]

I've just watched the video and there's one thing I can't work out - you are either a genius or totally insane

Both ! An insane genius - Muahahaha. But thanks ! I'll take the compliment. And thanks for watching my video.
What did YOU like from it? mister @Moley

 

[Moley]

I like the passion that you seem to put in to this project of yours. It also brings back memories of 4xxx series chips that I used to play around with. I wish I had kept some of my old projects but that was in the early '80s. If I had kept everything I had worked on over the years my house would be full.

 

[_q12x_]

I just buy 10pcs of your suggested CD4514 (4 to 16 Line Decoder/Demultiplexer)
And I give it a quick simulation and is doing the thing alright.
A bit expensive for my very poor pocket ... but is good to have interesting chips around.