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Logic Outputs Problem in 7493 IC

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_q12x_

_q12x_

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Hello from Romania.
I have all the counting ccts, for every number. This is counting to 16 and its the last one this 7493 can count.
I encounter a new and very weird problem. All the [Q] (QA,QB,QC,QD) outputs of the 7493 are not so good at outputting. At least to my components I tested so far.
[ElectriciansForums.net] Logic Outputs Problem in 7493 IC

I simulated more possibilities and all failed. I thought maybe the simulator is not that good. But when I tried the BJT in reality, it still didnt work. I really want to believe it will work with opamps in reality, but if it will not work, it means the simulator is right.
I didnt try with mosfets in the simulator yet, they were just prepared there. I didnt test them in cct.
THe problem is the (-) that 'comes out' after these buffering devices. When they are on (-) on their output.
[ElectriciansForums.net] Logic Outputs Problem in 7493 IC

I actually solved the problem using a tri-state buffer. They are the only component that are solving this issue.
Ive also get 10 pcs from aliespress. I start to value them now, when I actually need them. But they will arrive after 2 or so months from now.
- I want to find a solution (IF POSSIBLE) without them, or at least until they arrive.
[ElectriciansForums.net] Logic Outputs Problem in 7493 IC

This cct I already make and it is working fine (in the simulator) is to output a decimal number for all the 16 binary counts.
Pretty much when is 0100 it will lit the 4th LED. When is 1000 the 8th LED and so on, from 1 to 16 (including 0).
You can see in the screenshot already.
I work on this cct and numerous problems for .... about 10 or more days. Very hard to do it alone !!! But I did it. so far.

I even have an easier output method than this very complicated cct I already built.
- Simply to display in binary. Like these 4 LogicProbe from Proteus simulator that I am always take for granted.
So we can do these first !
[ElectriciansForums.net] Logic Outputs Problem in 7493 IC

To make a simple binary counter [LED display], I will still need some sort of buffer, like the ones I specified already.
I wait for your response. This is a very complicated cct and a big problem for me.
Thank you and hope I will get some interesting answers! (mister @marconi , my Logical friend?haha)
And also Happy New Year 2023 to everyone that are reading my posts !
 
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Yes, I had a (wiring) problem on #5 and I figure it out. All messed up. Thank god it wasnt a logic problem. And after I seen that #5 is working, I get courage and filled the full length of the breadboard , to #8 and all worked just fine. I didnt make it to 16 since I dont have that many CLEAN diodes (legs). So I get another courage, round 2, and Im starting and HOPING that these cardboard ccts will do their job. I plan to make it until 8, like I did it on breadboard, and then put that in front and after it, on the breadboard to make it to 16 and this way make a FULL count of all 16 of them. Im also making a movie about it... from pieces filmed in time, as I progress.
Thanks for the interest. It looks nice, right? Hehe. But is a ton of work. Hope I will make it today... Mmmm
 
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marconi said:
the decoder box on page 2 does not show any detail but you have worked out what is involved.
Click to expand...
I dont understand what you mean by that... You mean that I figured out how to connect these 4inputs to get my 16 modes ?
I actually searched and didnt find a BCD for 4 bits(binary) to output 16 modes (decimal). I didnt searched well enough I guess, because here you are with it. Very good that you show it to me !
Are they even bigger that this? with 32 outputs maybe? or 64? That will be cool to see ! Haha.
 
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An Update on the Progress:
[ElectriciansForums.net] Logic Outputs Problem in 7493 IC

Slowly but surely...
You can see the board # number - fix in the middle of it.
I plan to make a mini-BUS wiring for these 4 ... probably... and actually put them to work in the cct on the breadboard...
We'll see. Im so bored of them... already, at the 4th one....
[ElectriciansForums.net] Logic Outputs Problem in 7493 IC
 
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_q12x_ said:
I dont understand what you mean by that... You mean that I figured out how to connect these 4inputs to get my 16 modes ?
I actually searched and didnt find a BCD for 4 bits(binary) to output 16 modes (decimal). I didnt searched well enough I guess, because here you are with it. Very good that you show it to me !
Are they even bigger that this? with 32 outputs maybe? or 64? That will be cool to see ! Haha.
Click to expand...
One can use two 4 bit to 16 line decoders to make a 5 bit to 32 line decoder by using the enable (EN) logic inputs on the decoders to select which decoder outputs to use depending on the state of the 5th bit. I cannot find an image for 5 bit to 32 line but the idea is expressed well enough by this attached image which shows the use of two 3 bit to 8 line decoders making a 4 bit to 16 line decoder. You can see how the 4th bit is connected a NOT gate and then one decoder connected to its output and the other decoder connected to its input - thus only one decoder is enabled at any time depending on the logic state of the 5th most significant bit. When the 5th bit is zero the decoded output is one of 0 to 7 and when the 5th bit is one the decoded output is one of 8 to 15. I leave to you to draw out how to use two 4 to 16 decoders to produce 32 outputs, and then how to use four 4 to 16 decoders to produce 64 outputs.
 

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One-hot - Wikipedia - https://en.wikipedia.org/wiki/One-hot

As you are experimenting with n bit patterns/sequences I thought you would like to learn the names of those for binary, unary and one-hot. See the table top right of the wiki link above which illustrates them. Your project is a 16 bit one-hot generator.
 
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I have to receive this chip but later in the mail.
to arrive: 4028 CD4028BM x10 BCD-to-decimal Decoder
[Can you check for me, if it is possible to cascade multiple of them? Thanks.]
I re-checked and I have NO BCD in all my arsenal of chips. These are the first ones for me.
Also Im looking to your 4514 4- to 16-Line Decoder/Demultiplexer.. maybe is good to get some as well.
I call them BCD but maybe they work the same as Demultiplexers? Im not sure here. It sounds it might be.
If its the same thing, then I have already
74138-74LS138 x10 1-OF-8 DECODER/DEMULTIPLEXER (10pcs)
And thanks for looking into my video !
 
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The 4028 can be cascaded. See Figures 13 and 15 in this link:

https://www.ti.com/lit/ds/symlink/cd4028b.pdf?ts=1673700179941&ref_url=https%3A%2F%2Fwww.ti.com%2Fproduct%2FCD4028B

The 4028 is a 3 bit binary to 8 line one-hot or 4 bit binary coded decimal ( 0 to 9 in 4 bit binary ie 0000 to 1001) to 10 line one-hot device.

The 4514 can also be cascaded. The nice thing is that this one is a 4 bit binary (ie 0000 to 1111) to 16 line one-hot device. It can do bcd to 10 line one-hot.

See: https://www.ti.com/lit/ds/symlink/cd54hc4514.pdf?ts=1673772594066&ref_url=https%3A%2F%2Fwww.google.com%2F

The 74LS138 is a 3 bit binary to 8 line one-hot device. Since there are only 3 input bits (0 to 7) it can only select one of 8 output lines and thus does not do conversion of binary coded decimal (BCD) into 10 line one-hot. You need a 4 bit binary coded decimal word to do 0 to 9. The 138 can be cascaded.

See: https://www.ti.com/lit/ds/symlink/sn74ls138.pdf
 
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marconi said:
Since there are only 3 input bits (0 to 7) it can only select one of 8 output lines and thus does not do conversion of binary coded decimal (BCD) into 10 line one-hot. You need a 4 bit binary coded decimal word to do 0 to 9.
Click to expand...
Yes, so my real question with 74138 was if (any) DECODER/DEMULTIPLEXER IC can be used as BCD. And viceversa, any BCD as a DECODER/DEMULTIPLEXER. For you these things are trivial but they are very new to me. I really dont see the similarities/diferences between these 2 types. Very interesting.... thanks. I will have to pay more attention to my 74138 and see what you've seen/explained.
Also thanks for checking the cascade IC's for me.
I am currently hitting some very hard wall of errors with my boards I make. 1-from the scrappy components, 2-from very intricate connections, even if they are 4 to make, but when 1 goes to 3, in words sounds ok and easy, but there with those tiny wires, aaah, is hard. 3-not very, but too small spaces between the rails and the leg of the diode must hit 'in the zone' and not too much left or right. Get me? So there are even much more details like these, I will not enumerate all, but they are making this entire component extremly hard to make. I had to unsolder over 10 times the same board(s) and search and repair what was buggy and still I didnt figure it out. I did figure out 1 board, 1 diode that is functioning ok alone when measured but not in the cct, very strange. After I replace it, all got to normal working. But until I discovered the -------, took me 1 day. And the fun part, now when I put the second board on the rail, everything goes to hell again...aaaaah. I was VERY lucky with the 1234 module. No errors whatsoever. This one Im working right now is 5678. Im thinking to change tactics and make everything even bigger, to be able to repair and test and check and solder in the same time. Like I did on the breadboard. Well see. Very challenging. But I will make it work, one way or another. I dont like it BIG, but if this is what it wants to be...
 
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A coder/decoder or multiplexer/demultiplexer can do BCD to 10 lines one hot or vice versa provided that 4 bits are used for the binary input/output. Three bit words only covers the numbers 0 to 7 and therefore cannot cover the decimal numbering system which uses 0 to 9.

I am glad you are having fun! The effort required makes the success more satisfying (perhaps).
 
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