You won't need to guess if you describe in words the conditions you want to reset the counter.

Must:

QA-QC = L
QD = H

 

You seem to be practicing "design-by-happening", meaning that you try essentially random things will little to no idea what you should expect, but rather just hope that, eventually, something will just happen to do what you want.

dont worry i wont.. I now have an idea.. thank to him..

 

Must:

QA-QC = L
QD = H

Except that we're letting the count get to 9 before resetting the counter. If you look at the count sequence, you will see where you can simplify the reset logic.

 

ahhh i now know what should i change!! the A & D!! Cuz' B & C doesnt change


A 0 1 0 1 0 1 0 1 0 1
D 0 0 0 0 0 0 0 0 1 1

B 0 0 1 1 0 0 1 1 0 0
C 0 0 0 0 0 0 0 0 1 1

 

Don't forget to consider current limiting resistors for the display before you lay out your board.

 

Don't forget to consider current limiting resistors for the display before you lay out your board.

So i still need resistor? at the same place?

 

So i still need resistor? at the same place?

LS47 outputs will sink 24mA, but you can operate the display at a lower current. I'd try 10mA. One resistor per segment.

 

ahhh i now know what should i change!! the A & D!! Cuz' B & C doesnt change


A 0 1 0 1 0 1 0 1 0 1
D 0 0 0 0 0 0 0 0 1 1

B 0 0 1 1 0 0 1 1 0 0
C 0 0 0 0 0 0 0 0 1 1

B and C do change, but there are only 2 valid states (counts) with QD HIGH and the counter is being reset on the only one with QA also HIGH.

 

ahhh i now know what should i change!! the A & D!! Cuz' B & C doesnt change


A 0 1 0 1 0 1 0 1 0 1
D 0 0 0 0 0 0 0 0 1 1

B 0 0 1 1 0 0 1 1 0 0
C 0 0 0 0 0 0 0 0 1 1

If you got the gates as below, then you hit the JP...



Do you know to simplify the above circuit?

Allen

 

Me thinks "Elvis has left the building!"

 

But I am sure she'll come back with her next homework problem.

 

She worked harder than several others I tried to help with counter problems.

Normally I don't help with homework problems because the understanding from the student is low and the pace is too slow. Sometimes it makes me wonder if the teachers are part of the problem...

 

Back in the old days, when I was going to tech school for the US Navy, it was made clear to us that we needed to understand the BASICS before we could even begin to understand more complex circuits. The point was driven home when a substitute instructor came into class without knowing what we had already covered. The subject was "power supplies" and not knowing what we had covered, he started at the front of the lesson guide and asking if we had talked about each type. When he got to "Voltage Doubler" we announced that we hadn't had that yet. At that point, he closed the book, walked to the chalk board and started drawing, talking to himself, changing the drawing, talk to himself some more, repeat... Once he was satisfied with what he had drawn, he presented it to the class, explaining exactly how two diodes and two capacitors work together to have double the output voltage of a half wave rectifier. His final remark was something to the effect of, "Remember the basics. If you know them and understand them, you can combine them to do almost anything." That lesson has stuck with me since 1962 when we were lucky enough to have had a substitute teacher that day. He taught the most valuable lesson of all.

 

It troubles me to see so many students using simulators when they don't have a good enough understanding of the basics. I keep wondering who's at fault; colleges, teachers, students, ...?

These are very basic circuits that students should be able to do very quickly with pencil, paper, and what they've learned.

 

I think too many schools teach to the test, not teach so the student understands. In my past life (before retirement) I had been given the responsibility of conducting the technical interview for what we called NC Electricians. (now it is CNC) My boss had been after me for a long time to get back to school and get some kind of degree. It really didn't make any difference to the company as to what kind of degree, they just wanted a BS behind any supervisors name. Well, he got on my case once again, and I told him that I had looked into going back, but he had given me the additional task of conducting the interviews. He didn't understand how that would keep me from going back to school, so I had to explain it to him. He had me conducting technical interviews with folks that had a college degree in the subject, but couldn't tell me which of two different size capacitors connected in series would have a higher voltage across them when connected to an AC source. They couldn't think for themselves.

I told my boss that if that is what college does to you, I didn't want any part of it.

 

I told my boss that if that is what college does to you, I didn't want any part of it.

I must be about the same age as you. We're from a generation where a high school diploma along with some knowledge, intelligence, and initiative would allow you to do well. I'm not saying kids these days don't have those qualities; it's just that you need the degree to get your foot in the door. I pity the kids (and their parents) now who are going into debt to get an undergrad degree.

 

I finally did take the advice of my boss and go back to school. I got my double major BS a year after I retired. Neither major was in electronics.

 

She worked harder than several others I tried to help with counter problems.

Normally I don't help with homework problems because the understanding from the student is low and the pace is too slow. Sometimes it makes me wonder if the teachers are part of the problem...

Many, many times that are, indeed, part of the problem. But only part. It is a complex web of trends that is flushing the quality of graduates right down the drain -- in this and many other countries.

 

It is the fault of the teachers too.

I did not have good physics textbooks to learn from in high school. The textbooks are bad in my country. And I'm not saying that. It was even on the news once. How the textbooks are made gives me the impression that the author tries to impress other authors without thinking about the actual readers, the students. They are so bad that you do not understand those simple high school concepts and you start to think that maybe you are the stupid one.

Only when I came across the Giancoli textbook used by the students from MIT I was like: 'ooh, finally something that I can understand'.

In university the same story. How the theory was given by some teachers was too fact-related, too direct. Only when I came across the textbook written by Anant Agarwal, I started to understand more.

Maybe you guys had great teachers. And because you had great teachers you understood the material easy. And now you suppose that everyone understands it easy. And when you teach, you just state the facts, come with powerpoints, etc. But there is a difference between presenting facts and actually teaching.

Why are there so many teachers nowadays coming with powerpoint presentations and saying:'go search on google for more information'?

PS: at least that is what is happening in my country. I do not know what is the case in other countries.

 

There is definitely a trend toward pre-packaged curricula as more and more classroom material is made available by the publishers. In some ways this is good -- a lot of time and effort can be invested in creating good materials. The big downside is that it becomes pretty enticing for instructors to just download the provided material and then start reading from a script. It also increases the likelihood that instructors get courses dumped in their laps at the last minute since all of this stuff is pre-packaged and ready to go.

I much prefer using the whiteboard because it forces the lecture to go at roughly the pace that students can absorb the material and take notes.