Help with Project

[John R]

I am at a loss after reading online trying to teach myself so I figured ask the experts. I am working on a project in which I have a small water bowl that will empty by turning either 180 or 360 degrees and then returning back to the start point once per day. What I've read seems to say that I should use a step motor that is told how many steps to take, etc. My question is. I would like the easiest method to do this so to keep the project simplified. Can someone please help me I would greatly appreciate it.

 

[MikeMl]

Is the goal to slowly empty the bowl? If you are trying to deliver a measured amount of water every hour, for example, then this is not the way I would do it...

 

[John R]

The bowl will be attached to a rod attached to the motor and just needs to turn to empty. Speed doesn't matter. I will use a solenoid to release timed water back into the bowl.

 

[MikeMl]

1. Do you want to turn the bowl so that it sits in its nominal water-retaining attitude for 23+h per day, and then suddenly it flips over, spilling the water?

2. Or do you want to slowly, continuously rotate the bowl so that it gradually dribbles water over its rim, taking 24h to make a rotation?

3. Or do you want to rotate it slowly so that it takes 23+h to get inverted (180degrees of rotation), and the suddenly flip it back upright (the remaining 180degrees of rotation) in a few seconds?

 

[spec]

I am at a loss after reading online trying to teach myself so I figured ask the experts. I am working on a project in which I have a small water bowl that will empty by turning either 180 or 360 degrees and then returning back to the start point once per day. What I've read seems to say that I should use a step motor that is told how many steps to take, etc. My question is. I would like the easiest method to do this so to keep the project simplified. Can someone please help me I would greatly appreciate it.

Hy John,

Welcome to ETO. I see from your profile that you are from the United States- care to tell us which state and put it in your identity window on the left. This information is not only interesting but often helps us to give a more targeted answer, because we will know your mains supply, the parts you are likely to be able to purchase, and take into account any safety standards that apply to your local. The information also lets us know your time zone which is handy for posts and conversations.

The simplest and cheapest solution I could come up with to meet your requirement, is to use a normal motor geared right down, rather than a stepper motor, and configure a limit switch that goes open circuit when the bowl is in the vertical position. Then power the motor via the limit switch.

Then all you need to do, when you want to empty the bowl, is momentarily apply power to the motor and the bowl will rotate through one complete 360 degree revolution coming back to rest in the vertical position when the limit switch will open again and remove power from the motor. In the process the bowl will be emptied. The system will then be ready for the next empty bowl command pulse.

You could generate the empty bowl command pulse every 24 hours by a conventional timer.

As you are in the United States, parts for this project will be available from many sources and will be especially cheap from eBay.com.

If you favor this approach but don't have the experience to design it, just say, and I am pretty sure we can help out.

spec

 

[Les Jones]

Hi John,
Have a look at this thread . It is dealing with controlling the rotation of a motor so it does one revolution. ((I.E. 360 Deg.) It could also be modified to rotate 180 Deg. each time.

Les.

 

[John R]

Ok thanks. Im from Louisiana.
I only need the bowl to turn once per day otherwise it needs to be in its upright position to hold water until that time.
I like the limit switch idea as it seems the easiest however can you help me with the parts list?

 

[spec]

Ok thanks. Im from Louisiana.
I only need the bowl to turn once per day otherwise it needs to be in its upright position to hold water until that time.
I like the limit switch idea as it seems the easiest however can you help me with the parts list?

Hy John,

Louisiana looks good.

Sure we can help, but just a few questions:

(1) What supply will you use: mains or battery. Please give details.
(2) Can you give dimensions of the bowl and weight of the bowl both empty and with the maximum amount of water in it. The volume of water would do instead of the weight. A picture of the bowl, with a ruler close to the bowl, would be informative.
(3) What skills/experience/facilities do you have.

spec

 

[John R]

I would like to electricity from the house vs battery. 110 volt wall sockets. Of course the power adapter would need to match the motor.
The bowl is Round - 5 inch across and 2 inch depth - bowl empty is 4oz empty and 12oz with water
I can solder, I understand electrical basics - pos, negative, ground
I am handy so can figure things out and can fabricate what needs to be done to attach to the motor. The main focus is getting the motor and the needed supplies to get the motor to turn and land in the upright home location each time. It will only turn once per day and doesn't need to move fast or real slow. I guess a nice steady turn would work.

 

[John R]

Hi Les that coke dispenser is really cool. I get the just of what it's doing. The key for me is to have it to where I could have a digital timer active the motor instead of the switch so that it will operate whether I'm home or not. IE on vacation. This whole project is for my macaws to have water but their water bowl must be refreshed daily so hence the project.

 

[spec]

I would like to electricity from the house vs battery. 110 volt wall sockets. Of course the power adapter would need to match the motor.
The bowl is Round - 5 inch across and 2 inch depth - bowl empty is 4oz empty and 12oz with water
I can solder, I understand electrical basics - pos, negative, ground
I am handy so can figure things out and can fabricate what needs to be done to attach to the motor. The main focus is getting the motor and the needed supplies to get the motor to turn and land in the upright home location each time. It will only turn once per day and doesn't need to move fast or real slow. I guess a nice steady turn would work.

...The key for me is to have it to where I could have a digital timer active the motor instead of the switch so that it will operate whether I'm home or not. IE on vacation. This whole project is for my macaws to have water but their water bowl must be refreshed daily so hence the project.

Hy John,

Thks for the info- very helpful. Macaws any pictures?

spec

 

[spec]

I propose a mains 110V to 12V power supply which is turned on by a standard timer. The 12V is then connected to a 12V DC motor and limit switch. This is the safest approach as no high voltages would be involved in the area of the birds. The limit switch timing needs a bit of electronics but nothing too complex. I will give it some thought as will other members no doubt.

spec

 

[spec]

Hy again John,

Have you thought about a completely mechanical approach. Presumably you have some running water to refill the bowl so why not get the weight of the water in the bowl to provide the power. The principle being that when the bowl reaches a predefined weight it simply tips over and empties itself. Once the water has gone the bowel then returns to the upright position and refills. Alternatively, a small ballcock and valve could be configured to empty the bowl.

spec

 

[KeepItSimpleStupid]

Why turn the bowl? Can you just empty it? Valve on the "drain"?

Turning may help get rid of debris in the bowl, so that option is fine.

I would envision a low voltage 24 VAC synchronous motor (Hurst motors). 24 VAC for safety. These motors usually require a capacitor that's supplied. See: https://www.hurst-motors.com/permanentmagnetacsynchronous.html the surplus market may work for you.

What you basically need is a disk with a depression along the edge in the up-right position where a roller micro switch resides.

The roller micro is designed to run the motor when it's not in the circular notch. The synchronous motor will generally stop instantly unlike other motors.
Thought needs to go into powering stuff. Low voltage for safety for the limit switch makes sense.

To make the bowl dump, you just have to short out the micro with a timer for a short amount of time.

If you can live with more than a minute to turn the bowl the project gets simpler, I think. Because timers with minute resolutions may be more common.

I doubt you need much torque, but that can be measured with a cantilever and weight or a spring scale and cantilever.

"smart relays" (Basically mini Programmable logic controllers)

here **broken link removed** is just one brand of a low cost controller. It can do the time, rotate and fill for you.

 

[spec]

First thoughts: Scheme #1 (mains PSU & timer. 12V DC motor) Issue 05 2016_04_28

(1) Motor (12V DC geared down): https://www.robotshop.com/en/cytron-12v-12rpm-166oz-in-spur-gearmotor.html
(2) Power supply (wall wart switch mode 110V to 12V DC): https://www.robotshop.com/en/12vdc-3a-wall-adapter-power-supply.html
(3) Timer (mains 110V): https://www.ebay.com/itm/CN101A-AC-...imer-Time-Switch-Relay-16A-Amps-/171937345408
(4) Limit switch: https://www.robotshop.com/en/micro-switch-5a-250v.html#reviewBox
(5) Connector, barrel (to mate with PSU connector): To Be Defined
(6) Braking diode (Schottky 1A min 24V min): To Be Defined

The minimum time for the timer output contacts to be made is one minute. This means that the bowl would rotate for one minute before coming to rest in the vertical position.

spec

 

[Les Jones]

Hi John R,
Here is one solution that should work.

The 12 volts power supply would be fed from the plug in timer which would be set to come on for a couple of minutes (Depending on the speed of the motor.) each day. This is how it works. When the 12 volts is applied to the circuit the transistor turns on when it reaches about 10 volts. This cause a positive pulse to be applied to the gate of the SCR via the 4k7 resistor and the 1 uF capacitor. The SCR will latch on starting the motor. When the motor has moved so that the notch in the cam causes the micro switch to close the motor current is then supplied by the micro switch. This will cause the SCR to unlatch. (As it is shorted out.) The motor now continues to rotate until the notch in the cam causes the micro switch to open which stops the motor. Nothing then happens until the 12 volts has been removed and reapplied. NOTE The resistor between the collector of the transistor and 0 volts should be about 100 K. (It has almost 24 hours to ensure the capacitor is discharged. ) There are many alternative ways of achieving the same thing.

Les.

 

[alec_t]

A car wiper motor (although more powerful than really needed) would provide most of the mehanical parts, the correct action, and just need a short trigger pulse daily.

 

[KeepItSimpleStupid]

Adding to post #15, a monostable timer such as **broken link removed** in mode P-1, eliminates the 1 minute issue. The timer would be activated for x seconds by the minute timer.

12 VDC motors may over-run, so the relay activating them may need to be configured as a brake when off. Simple. The motor windings are shorted when the relay is off.

 

[spec]

12 VDC motors may over-run, so the relay activating them may need to be configured as a brake when off. Simple. The motor windings are shorted when the relay is off.

I did think of that Keep, but then there would be no way of turning the motor on.
In general, geared down motors don't tend to overrun too much and small motors don't tend to brake well by placing a short across them. I have proposed a braking diode though.

As a 3 Amp PSU is specified and the motor only takes around 1 amp worst case, say, you could put a 5.6 Ohm resistor across the motor to act as a brake if necessary.

spec

 

[John R]

First here's a few pictures of my girls that I am doing the bowl for. Bella and Ruby.