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strongheart
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I live in a 40+ year old apartment building.
Maybe the elevator is controlled with an MCU, but how could it be controlled without one? Can it? with simple logic gates? (of course it can)
When responding to a multitude of down calls, how can it know to go to the highest floor first?
When there are 2 or more elevators, how to design the logic that they both don't answer the same call?

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Inq
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Is this a question out of pure, academic curiosity or a potential project.  Elevators are so heavily regulated (even more than fire-martial) that you'd never be able to actually attach a hobbyist level MCU to it legally.  And even illegally, I wouldn't want it on my conscious the one time it failed.

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Ron
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Posted by: @strongheart

I live in a 40+ year old apartment building.
Maybe the elevator is controlled with an MCU, but how could it be controlled without one? Can it? with simple logic gates? (of course it can)
When responding to a multitude of down calls, how can it know to go to the highest floor first?
When there are 2 or more elevators, how to design the logic that they both don't answer the same call?

@strongheart I used to have a friend that was an elevator mechanic. He and I took electronics in HS but I was a better theorist than he soi he asked me to help him design an elevator controller. That was about 55-60 years ago. I don't remember using any solid state devices, just relays. The basic circuits were trivial, it was all the safety lockouts that were tricky. He ran into difficulties with regulations and red tape so I never got to complete the project but I am sure it would have worked.

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Ron
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@inq EXTREME reality model RR'ing! IIRC, was there not at least one 2 level roundhouse somewhere? Maybe in Switzerland?

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strongheart
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@inq Yes this is purely academic, and I think a very good logic problem-  and perhaps a historical expose of how technologies of earlier periods solved the mechanics.

 

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strongheart
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@zander So how without solid state curcuitry did an elevator respond to all the down button calls by going up to the highest floor first?
I have worked on 2 elevators, on just a chair lift, the other a 50 year old 4 story lift in an Asbury Park hotel.  One of the bakeolite levers was damaged and needed mending to repair.

 

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Ron
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@strongheart Konrad Zuse used telephone relays on his Z2, a forerunner to the world's first programmable computer the Z4. I worked on a roughly similar machine during a summer job at Westinghouse. They produced a device I will call a 'computer' that was used to control the cross Canada pipelines. IIRC they were Bell 103 relays. I also worked with other IBM machines that used relays for logic. So, yes it's possible to do basic logic with electro mechanical devices, in fact the Toronto Science Center used to have a relay based OR AND NEGATE demonstration board built with relays.

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Ron
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Posted by: @strongheart

@zander So how without solid state curcuitry did an elevator respond to all the down button calls by going up to the highest floor first?
I have worked on 2 elevators, on just a chair lift, the other a 50 year old 4 story lift in an Asbury Park hotel.  One of the bakeolite levers was damaged and needed mending to repair.

 

@strongheart Since I designed that about 55 years ago and I now have trouble remembering what I had for breakfast, I don't remember, but just off the top of my head, at each floor, close a limit switch then notice the down circuit is still hot so keep moving up. Basically the electro mechanical version of an AND circuit. By tripping the floor switch that leg of the AND is turned off (some sort of latching req'd) and the elevator carries on. The physical distance between the UP floor switch and the floor stop switch is a mechanical adjustment made to allow he brakes to stop the elevator in time. More sophisticate and expensive elevators stopped slowly but older cheaper stopped hard. Do you remember those? Going down was called doen collective, in other words each 'down' call was answered as you came to that floor. Today that is known as an OR.

It is considered poor judgement to traverse a chasm in 2 leaps.


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Inst-Tech
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Posted by: @strongheart

@zander So how without solid state curcuitry did an elevator respond to all the down button calls by going up to the highest floor first?
I have worked on 2 elevators, on just a chair lift, the other a 50 year old 4 story lift in an Asbury Park hotel.  One of the bakeolite levers was damaged and needed mending to repair.

 

HI @strongheart, indeed it is very possible to operate an elevator with just electro mechanical relays...back in the 1971, I built a 5 push button alarm system that had a hard wired combination for my home garage. Built an electronic siren and used a 35 watt juke box amplifier for the alarm..you could hear it all over the neighbor when it went off at noon every day to test the system and let everyone know it was 12 noon...lol

LouisR


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Inq
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Posted by: @strongheart

@inq Yes this is purely academic, and I think a very good logic problem-  and perhaps a historical expose of how technologies of earlier periods solved the mechanics.

 

I quite agree that it would be an interesting logic problem.  Since they used human operators at first, I'm betting they totally relied on the operator to be the computer and there was no mechanical/electrical devices for when to stop at a floor or even to align with the floor.

In your case of a ~40 year old one, I'd expect it's computer controlled even if it is using original computer.  But the point is well taken... what did they do between human operators and the first electronic computer?  Just using relays and trip switches... I would think would be a mechanical logic nightmare. 

Doing it these days... an encoder on the motor might be all that is really needed hardware wise.  It probably still has floor switches to validate, but the software logic would be pretty strait forward... not easy... just systematic and strait forward.  

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Ron
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@inq Your timeline is mostly correct.

1. Human only, operating a motor on/off button.

2. Human as computer, operate a button but final braking and positioning by mechanical switches. I remember those in local department store.

3. No humans, just relays. I serviced those and designed one.

4. Modern solid state computer like controls today.

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Inq
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Posted by: @inst-tech

...35 watt juke box amplifier for the alarm..you could hear it all over the neighbor when it went off at noon every day to test the system and let everyone know it was 12 noon...lol

How to make friends and influence people.  Your so bad!  🤣 

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Even usable on ESP-01S - Quickest Start Guide


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Inst-Tech
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Posted by: @inq
Posted by: @inst-tech

...35 watt juke box amplifier for the alarm..you could hear it all over the neighbor when it went off at noon every day to test the system and let everyone know it was 12 noon...lol

How to make friends and influence people.  Your so bad!  🤣 

Yep..I know it..but it was fun to aggravate the neighbor's back then..the real reason for the alarm was because we had had several day time break in's where they used a moving van to clean you out..the alarm going off every day at noon apparently help make the neighbors more aware of what was going on in the neighborhood.

Regards.,

LouisR

LouisR


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strongheart
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@inst-tech Back in the day when you could dial zero for an operator and ask her what time it was, one operator had a call sometime before Noon every day, usually 11:55 and he'd ask her what the exact time was. 
Well after about a year she finally asked, "You've been calling me every day just before noon, why do you do that?"
"I'm the fire chief and I need to know the exact time so I can blow the noon whistle."
"Oh wow, I set my watch by that whistle"

How can things fgo wrong here?

 

 

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Taking someone else, seriously, it's a federal offense.


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Ron
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@inst-tech I am always intrigued by my American friends who actually know people who have had their home's broken into. I live in Canada, and I don't know a single person this has happened to and other than one case (me) of a joy ride of a couple hours do not know of anyone who has had a car stolen. One of my former work associates from NJ had her car stolen 5 times in a couple months.

It is considered poor judgement to traverse a chasm in 2 leaps.


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