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Dumbwaiter Logic Circuit

Windhorse1960

Jan 11, 2018
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I'm electrifying an old dumbwaiter and going to utilize a power winch similar to what is used in a garage, with both up and down controls.
At this point I do not have the winch, but "presume" the wired switch to be 12v.; the winch itself is 110v and can lift up to 400#, however the max capacity will never exceed 150# given the size of the car body.

The project would be easy, except that the house has three floors, and we would like to call and send the dumbwaiter to each floor as necessary.
I had planned on the following:

* Each floor has a stop switch to indicated to control which floor the platform is on;
* Each floor's door has a safety switch on the door to prevent any movement if it is open;
* Each floor has an external series of switches to call to that floor or send to another floor.

Therefore the logic is as follows:

3rd Floor
Up to floor 3 (unless position switch already engaged)
Down to floor 2 (unless position switch already engaged)
Down to floor 1 (unless position switch already engaged)

2nd Floor
Up to floor 3 (unless position switch already engaged)
Up or Down to floor 2 (unless position switch already engaged)
Down to floor 1 (unless position switch already engaged)

1st Floor
Up to floor 3 (unless position switch already engaged)
Up to floor 2 (unless position switch already engaged)
Down to floor 1 (unless position switch already engaged)


Simple latching relays for everything would be easy, with the logic of the 2nd floor "Up or Down" being this: if the car was on the 1st floor and the center button was pushed to call it to the 2nd floor, no power would be sent to the winch "down" controller since the car was already on the 1st floor, thus engaging the bottom safety; the "latch" wouldn't take, and the "up" control would engage. Same scenario if the car was on the top floor..

Ancient as I am, I know this could be accomplished with old fashioned latching relays, however I'd like suggestions and schematics for other suggestions with stable and safe logic control.
Please, no Arduino plans... I try to adhere to the KISS principal.

Thanks in advance.
 

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BobK

Jan 5, 2010
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Sorry, but a microcontroller IS the KISS solution.

Bob
 

AnalogKid

Jun 10, 2015
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You said the winch motor is 110 V, but you didn't say AC or DC.
Is the winch motor reversible?

An Arduino output can directly drive a standard solid state relay. With all of the logic inside the Arduino, there are only two relays required, up and down.

ak
 

Minder

Apr 24, 2015
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There is a fair amount of logic involved, so if not wishing to use an Arduino, there is the possibility of using a SmartRelay, there are a few manuf. or even its bigger brother, a small PLC.
The outputs of which can drive the contactors needed etc.
I assume you will also need indicator status lights at each floor.
M.
 

Windhorse1960

Jan 11, 2018
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Here's the winch I'm proposing to use, and it looks like it's a 110v reversible motor per se from the gauge of the cable going to the remote control; the manufacture claims it's a "running startup capacitor magneto motor".

That being the case, I do not know at this point:
a) the voltage to the wired switch, or
b) the amperage to the wired switch
Presumably it's a straight-through connection, so a resistor or relay circuit might be necessary at that point of control, which is not an issue.

As to logic, most of this is straight forward as safety switches must be in place either way in order to prevent upward movement at the top (or vise versa), along with those at the doors so that the unit would not operate when they are open.
No status indicators will be necessary as it's just extra wiring and foof. You either call the car to your location by the buttons (your floor being the black button) or send it elsewhere (as indicated by the arrow buttons with numbers)

The question is all about using solid state versus old fashioned mechanical latching relays, and given the perimeters, the best circuit options.

Thanks all so far for the requested clarifications.
 

Minder

Apr 24, 2015
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Most control logic now is 24vac or dc, with DC being the more prevalent.
For all the interlocking you are using, I would hesitate to do it purely by relay and limit switch alone.
, Even a small system like this would benefit by some kind of logic controller.
If for no other reason that making hardwired changes and necessary mods etc.
I would use a reversing contactor for the motor, these have both electrical and mechanical interlocks,
The motor appears to be a standard 1ph induction motor and also probably has a brake which could also be picked up by the same contactor, if electric operated in nature..
M..
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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You also need to consider the speed of your dumb waiter.

Depending on any number of characteristics, if the motor is just turned on our off, the case may start and stop with a jerk. That may be fine for moving some items, but less so for others (souffles, for example). More importantly perhaps, this jerk will place large stresses on the mechanical components when the car is heavily loaded. You may want to consider some form of soft start and stop for the motor. Once you do this, your logic gets more complex because the car needs to know it is getting close to a stop so it can slow down rather than moving past the stop as it decelerates.
 

kellys_eye

Jun 25, 2010
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Each floor has an external series of switches to call to that floor or send to another floor.
Doesn't this introduce unnecessary complication? Surely a simple 'call' button for each floor would be sufficient given there 'must' be someone at the relevant floor to take receipt of the goods?

On a normal dumb waiter this is the case with the hatch being the interlock.

In this case you'd be looking at a standard 'lift call' system for which, I'm sure, there are simple relay logic diagrams available.
 
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