If the 2 push buttons are used in more than one result, then a multi contact relay is needed for each, i.e. start and stop relay and up to 3 relays to store the result of the logic table.
If I get a chance I will take a crack also.
I am also interested in the 'official' answer?
Max.

 

Doesn't seem possible with the given limitations.
Must be something that we aren't being told.
3 control relays? cmon!

I found a way to make a two relay T flip flop work using the trial and smoke method.
Uses some illegal design but works well.
May have an error in drawing but the spaghetti works great.

Still believe it has to be the basis for memory in relay logic. I won't begin to try the riddle. Smarter people on here are stumped.

 

Think I have it figured it, but I can't really post it on here since my other classmates will certainly be googling this soon.

Private message me if you want my circuit.

And perhaps I wasn't specific in my explanation ( I apologize, obviously new to the field ).

The control relays we use have three normally closed, and three normally open contacts, if anyone thought there was a contact limit of three, I apologize.

 

I saw his circuit, looks good on paper. Very impressive. I was wrong. One more example of "The quickest way to find out how to do something is to say that it's impossible." But as I told him,

unless you show the solution in public, there's won't be any public shorts eating.

 

Thanks everyone! I'll be able to build and test/troubleshoot it on thursday, so if it turns out to be a bust I will admit it and come here crying again.

 

Looks good to me.

The only question I have is possible timing. On the first press if M is large and slow. Could cr pull in M2 before M/nc breaks?
I take that back. Cr is delayed by pull in time of M.

The instruction were misunderstood by me.
I noticed the need to be able to stop motors between sequences. What I did not know is that it was required to do so.

That takes away strantors requirement for timing.

I don't think I've posted a spoiler. If I have let me know and I'll delete.

 

I see a problem, but I am not sure if it is due to the unclear instructional labels?
Max.

 

I found a way to make a two relay T flip flop work using the trial and smoke method.
Uses some illegal design but works well.
May have an error in drawing but the spaghetti works great.

This type of a circuit work very good. I also build it in 2005 when I star working with PLC. But you cannot use it in PLC.
In PLC we use different diagram.

 

Surprising, don't know this kind of course is not popular for an EE.
I am taking a course about Programmable Logic Control this semester and I will ask some questions about it.

 

I'm not aware of any current EE curriculum that includes them -- though I am sure that there are going to be some, particularly in programs that lean more toward power and industrial control.

I've never had any formal education in ladder logic. My only significant exposure was the wiring diagrams for the hydraulic test stand I worked on in the Air Force and I had to figure out what everything meant on my own. Doing so was actually rather fun, but of course if the test stand didn't use something, then I got no exposure to it at all.

Well as an undergraduate, we used Norman Scott's book Analog and Digital Computer Technology, 1960. In the history of computers relays came before tubes, transistors, and integrated circuits.

 

Think I have it figured it, but I can't really post it on here since my other classmates will certainly be googling this soon.

....

Foul Ball!! This is like bait and switch!!

You get our help and then don't share the result! Sheeesh

What do you care if they do or don't copy your solution as long as you got it right. If they don't understand the solution it will be obvious on the next exam.

 

In the history of computers relays came before tubes, transistors, and integrated circuits.

And Boolean Arithmetic preceded computers by almost 100yrs.

You get our help and then don't share the result! Sheeesh

It is there if you PM him?
Max.

 

And Boolean Arithmetic preceded computers by almost 100yrs.

Sho 'nuf

It is there if you PM him?
Max.

I don't care about the solution for myself, but I do care about the idea of showing and sharing results in the open forum. I've had a bellyful of NDA's and proprietary secrets; I'm sick and tired of it and I'm not going to suffer it cheerfully anymore --- or Nevermore quoth the Raven!

 

Because the circuit counts for only a single grade, of over 30, and will not be test able. The entire point of the job is to muddle your way through it, and any classmate that asks for help from me assuredly would get it, but as customary here as far as I've seen, answers aren't simply handed out like treasure, but you're given a map.

 

I see a problem, but I am not sure if it is due to the unclear instructional labels?
Max.

Someone else also noted a problem regarding the sealing contacts for motor 1 and motor 2, not sure if that's what you're referring to.

Edit : Also, if it's any sign, both my professors said it would work.

 

I think it was the timing of the control relays?
I will have to pull it up again.
Max.

 

I will set up the PLC simulator and see what pops up.
It is not quite the same as relay logic due to the timing between hard wired relays and contactors, but it might show a weak spot.
Max.

 

Sho 'nuf




I don't care about the solution for myself, but I do care about the idea of showing and sharing results in the open forum. I've had a bellyful of NDA's and proprietary secrets; I'm sick and tired of it and I'm not going to suffer it cheerfully anymore --- or Nevermore quoth the Raven!

In fairness, it was stated that the reason for not posting the solution was because of the concern that other students working on the same homework were likely to find it. Thus, for the same reason that we discourage just posting solutions, they are holding back on posting this until after the assignment due date. Not an unreasonable thing to do.

 

Foul Ball!! This is like bait and switch!!

You get our help and then don't share the result! Sheeesh

Also, in all fairness, he did figure it out himself. Our (or at least my) help wasn't very helpful. I think he takes/deserves all credit for it. If it were me, I would post the solution, but it isn't, and I respect his IP.

 

I started plugging it into the simulator and realized right away a problem.
If M1 and M2 are the motor contactors, then there is nothing to retain them once the N.O.? start button is pushed and released?.
Max.