First Electrical Engineering Lab, Need Help!

MrAl

Joined Jun 17, 2014
8,390
Its hard for me to follow everything you're saying with my knowledge but you explained it well, I thought that showing variables as switches was the way you were supposed to on the simulator but I changed it to just a text box. Let me know what you think now, thanks!

Edit: I can draw up gate diagrams using the basic gates pretty well by using the order of precedence even with moderately hard equations like in my lab. Im also pretty good with the truth tables. However, the main problem I'm having is understanding how it works with the chips, power, ground, switches, led, resistors (hands on stuff) ect as I have not had ANY experience with even basic wiring or any of that stuff. I guess the logic behind it is what confuses me right now like in the post above I didn't know that you needed resistors or what exactly they do and where to place them. It is only my first week of getting into this stuff but I want to try and get ahead and you guys are helping me out so thanks!

(I'm getting an analog and digital design trainer with the 7400, 7402, 7404, 7408, and 7432 chips with wires this week so I can start learning how to apply it hands on.. Id love to get suggestions on what else I should get to help out as well)

Hi,

Yes that looks very good

That takes you through the first step...going from equation to symbolic logic. Once you get that for any circuit, then you can move on to the actual implementation which can take many forms such as CMOS, TTL, LSTTL, ALSTTL. FTTL. HCMOS, HCTTL, ECL, too many to mention them all. In each of these cases you could use the same symbolic logic drawing, but there will be differences for inputs if you use switches, and power supply differences, and differences if any clock inputs are switched. So your first step is to convert the equation to logic symbols, then start to think about the logic family that best suites the design task. You can then start to fill in the details of what other parts you might need like pull up or pull down resistors, and then start to figure out the actual physical wiring scheme which may require some thought about how long a given copper trace can be. So going from the symbol diagram to physical layout requires a different thought process.

Hunter Neumann

Joined Aug 24, 2015
53
You've come a long way in a couple of days!

So I'm happy with these two diagrams to turn in but I want to make sure I diagrammed them right. The cadet training system that I am modeling the diagram after has switches so should I change my diagram to have them instead of just power? Just trying to get it as accurate as possible (the picture of the board is there) Would love to see what if anything you would change about what I have. Thanks

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GopherT

Joined Nov 23, 2012
8,012
So I'm happy with these two diagrams to turn in but I want to make sure I diagramed it right. The cadet training system that I am modeling the diagram after has switches so should I change my diagram to have them instead of just power? Just trying to get it as accurate as possible (the picture of the board is there) Would love to see what if anything you would change about what I have. Thanks

The decision on switch vs. direct connection to power/ground will be up to you and your professor (what does he expect). I have never taken an electronics class so that is all you or whoever is willing to help.

Hunter Neumann

Joined Aug 24, 2015
53
The decision on switch vs. direct connection to power/ground will be up to you and your professor (what does he expect). I have never taken an electronics class so that is all you or whoever is willing to help.
True, so if I did add switches would it just be the spst connected to power with a 1k resistor connected to each?

GopherT

Joined Nov 23, 2012
8,012
True, so if I did add switches would it just be the spst connected to power with a 1k resistor connected to each?
Default is (1) in this case - when switch is open.

Or, default is (0) in this case - when switch is open.

Hunter Neumann

Joined Aug 24, 2015
53
Default is (1) in this case - when switch is open.

View attachment 91165

Or, default is (0) in this case - when switch is open.

Hate to keep bothering you about this stuff as I'm sure its really trivial, but if you wouldn't mind I added the switches and would like your input. Do you think this represents it well? The reason I want to put them in is because we had switches on our training device. I do realize that you can't know specifically what our professor would want but I'm pretty sure based at looking at other students hand drawn diagrams he would take just about anything that was close lol. I think this more accurately represents it because you can only turn the whole device on or off therefore the different variables would either all have 0v or all have 5v and you can only represent this by connecting a switch to each one. Thanks!

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GopherT

Joined Nov 23, 2012
8,012
Hate to keep bothering you about this stuff as I'm sure its really trivial, but if you wouldn't mind I added the switches and would like your input. Do you think this represents it well? The reason I want to put them in is because we had switches on our training device. I do realize that you can't know specifically what our professor would want but I'm pretty sure based at looking at other students hand drawn diagrams he would take just about anything that was close lol. I think this more accurately represents it because you can only turn the whole device on or off therefore the different variables would either all have 0v or all have 5v and you can only represent this by connecting a switch to each one. Thanks!
1) The 5 volt sources you use for the inputs are the symbols for batteries. There is a ground on the negative terminal and you take the 5v from the positive to make the (logic 1) 5V input. It would be better to redraw as you will use a positive rail from your simulator instead of a battery for each x, y and z point.

2) Finally, notice (on your current drawing), that the input is not connected to 5V and it is not connected to 0V (ground) when the switch is open. Also notice that you have no resistor - as in the two drawings I showed you in the previous post.

Hunter Neumann

Joined Aug 24, 2015
53
1) The 5 volt sources you use for the inputs are the symbols for batteries. There is a ground on the negative terminal and you take the 5v from the positive to make the (logic 1) 5V input. It would be better to redraw as you will use a positive rail from your simulator instead of a battery for each x, y and z point.

2) Finally, notice (on your current drawing), that the input is not connected to 5V and it is not connected to 0V (ground) when the switch is open. Also notice that you have no resistor - as in the two drawings I showed you in the previous post.
Is this a better diagram? anything I did wrong or could do better? I just kind of winged it off of what I think you meant. Thanks for the help!

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GopherT

Joined Nov 23, 2012
8,012
Is this a better diagram? anything I did wrong or could do better? I just kind of winged it off of what I think you meant. Thanks for the help!
You've got it my friend.

Make sure it works as expected and move forward.

Hunter Neumann

Joined Aug 24, 2015
53
You've got it my friend.

Make sure it works as expected and move forward.
Great! so last question for this lab. Do you think these are A worthy diagrams to turn in instead of that crappy hand written stuff I turned in before?

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GopherT

Joined Nov 23, 2012
8,012
Yes, with the caveat that he may squak because the software is not consistant in the way it shows wire crossings. Sometimes a gap of the under wire when anothe crosses over the top and sometimes not. But, it always shows a dot when there is a connection. So you might want to make a key to indicate the dot indicates connection. Your preference.

Cheers.

Hunter Neumann

Joined Aug 24, 2015
53
Yes, with the caveat that he may squak because the software is not consistant in the way it shows wire crossings. Sometimes a gap of the under wire when anothe crosses over the top and sometimes not. But, it always shows a dot when there is a connection. So you might want to make a key to indicate the dot indicates connection. Your preference.

Cheers.
yes that is a good point, Ill make a key. Thanks again!

Hunter Neumann

Joined Aug 24, 2015
53
Final inputs for anyone interested in how they turned out!

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JoeJester

Joined Apr 26, 2005
4,390
I would neaten the schematic diagram up a bit, to easily explain the formula you posted ...

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