Help with Project

[spec]

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

They are great characters, macaws. Thks for posting pics.

spec

 

[John R]

First thanks for so much help. Now. I'm dizzy. You guys know your stuff WAAAYYY beyond my tiny brain. The amount of time it takes to get the bowl around doesn't really matter. The key is dumping the food that the birds like to soak so that I can limit the amount of bacteria growth and simply to keep the water as fresh possible. These birds have 3 to 4 foot wing spans but can die pretty easily if not maintained properly.
I used an eheim auto fish feeder, modified it, attached the bowl to it, and it worked exactly how I envisioned. Problem is the motor is designed to dump small pellet food and not a bowl of water so the motor won't last long at all. Secondly it's battery powered and I would really rather electrical simply because it's more reassuring that the bowl will have power vs batteries dying if I'm out of town.
I opened up the Eheim and it has a switch that gets pressed which tells the motor to stop. The shaft is round but one area is flat. This flat spot hits the switch and makes is stop. I think someone mentioned this style but the language got me dizzy and I'm not sure if I can build something like that?

 

[John R]

Les it was your version that seems to mimic the auto food feeder but is this something that is difficult to build? I don't care anything about cost to get this project completed. Definitely no hit against anyone else's idea. I may be partial to Les's simply because I know a tad bit of what he's talking about because of the feeder I tried.

 

[John R]

Spec #15 - that switch is exactly what's in the feeder. I like that you gave me a product list and places to find this stuff as that's difficult for me if I don't really get the language. Just getting home from work so going through each option hoping I can manage to build one. Thanks!!

 

[Les Jones]

Hi John,
The motor that spec gave the link for in post #15 (Or a similar one to suit the batteries that you plan to use.) will only need a disk mounting on the shaft with a notch cut in the edge. The micro switch would be mounted so it was actuated by rubbing on the disk. (You can get micro switches with a roller on the end of the actuating lever which would make it work better.) When the notch came round to the micro switch position the lever would drop into the notch and de activate the micro switch. Now some questions. What kind of battery are you thinking of using to power the unit . (For example car battery, 12 volts SLA alarm backup battery, Lithium cell / battery or an number of AA cells.) How long will it need to power the unit for ? My original suggestion was based on the idea of using a mains plug in timer. (These are cheap to buy in the UK.) I can't think of any cheap battery powered timers at the moment. There may be central heating timers that are battery powered. (We have a programmer that is battery powered but it is quite expensive as it contains a thermostat as well as the timer.) Some other thoughts. What system are you planning to use to re fill the bowl ? You could possibly use a garden watering timer for this purpose. If wasting some water did not matter then the start of the water flow could trigger the bowl rotating.

Les.

 

[John R]

Les I don't want to use a battery. I would rather use mains from the home. Sorry if I confused you. The refill of water will be plumbed straight from a Reverse Osmosis water system I have for my reef tank. I will use a timer and a solenoid valve to release water at a specific time after the bowl is emptied. I have this type of refill working on my reef tank and it's a proven option. My question going back to the micro switch. If the indention tells the motor to stop, then how can I tell it to start again or basically tell it to ignore the micro switch?

 

[KeepItSimpleStupid]

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

I don't quite understand what your trying to say. Not unusual.

Earlier I mentions lots of stuff goes into the selection and surplus parts isn;t a bad way to go for a one of especially if you buy two for the repair aspect.

I computerized a model gantry crane for a model railroad. It used 6 V geared motors. So, you can use an SPDT relay, just arrange it, so the motor is shorted when the relay is not energized. The motor acts as a generator into a short. For small motors, this works fine.

You missed the point. e.g. Common to Motor (+) , NC to ground, NO to +12, motor (-) to ground.

relay off: NC contact grounds motor
relay on: NO contact is now closed, powers motor(+) contact.
It's just not the NORMAL way to think.
So, you can still turn on the motor.

Aside: Some H-bridge ICs have FWD, REV, coast and brake options with the not enable being a way to introduce PWM for speed.

You can see the general idea here **broken link removed** with a pic of "cam timers". For one position, you just need a circular depression.
**broken link removed**
This switch isn't a roller, but it works. I did a 4 position optical filter wheel with position indication using a variation of this method and a 24 VAC motor.

Aside: Since it was micro base, I could sense if the motor was running (I/O module) and I could bypass the switch. Two Hall effect sensors and screwable magnets could sense the position. 00 or 11 could be moving or position zero. When combined with not moving, the position was well known.

I did a film advance mechanism (timing and match based only) to move a PTFE curtain so it could pass UV light to the process. As the curtain fouled, a clean PTFE area was moved into place. So, timing worked there too.

I "mentioned" the likely 1 minute resolution of timers which you picked up on.

So, the main requirements are low voltage and a sealed mechanism (motor/switch) at least, A possible local push button to dump it manually.

The third requirement is the fill. This is where the smart relay could come in handy as well as knowing whether or not the bowl is moving.

A "future" enhancement might include empty bowl detection.

Dumping has the advantage of removing debris.

If we go yet another step, there could be a spray function added where the bowl is cleaned.

So, design the BMW (Cadilac) and then decide what functions are immediately needed.

Let's say rinsing would be a second position of inverted and a spray pointed up. With a "little" work, the two positions could be accommodated. A place to put the rinse nozzle could be designed, but not built. The box would be sized to accommodate two cams. Initial tests just done using time.

Dumping the bowl presently may tell you whether or not cleaning is necessary, but it may not because I bet someone automatically cleans the dish if it's dirty when it's filled.

Then there is the 12 VDC, 24 VAC, 120 V GFCI protected stuff etc.

What I have found is that no one knows what they really want until you build/program it. then they say ... Can you add this or that?

It's also agreed, that we don't know everything about the install. Inside/outside dump into ground or something else wasn't talked about, so we are just dealing with how to do it electro-mechanically. We start out with a "poor description" of the problem. I initially thought "dog water dish".

 

[KeepItSimpleStupid]

My question going back to the micro switch. If the indention tells the motor to stop, then how can I tell it to start again or basically tell it to ignore the micro switch?

You "temporarily" bypass the microswitch long enough for it alone to keep it rotating on it's own. It could be a few seconds.

Timers may have a 1 minute minimum time period. So, if it takes 2 minutes to rotate the bowl, one minute works and you don;t need something to provide a 10 second push on a minute time resolution. e.g. The time is on from 9:00 pm to 9:01 PM and off every other time. The 1 minute is because of the timer design.

You can take that 1 minute interval and shorten it with a mono-stable timer. The "rising-edge" creates a pulse of a desired width.

"Manual" dumping of the bowl is just another switch across the microswitch.

Other issues are the contact rating of the microswitch.

Take a jar lid, fill with Epoxy filler and then file a depression for the rocker. Take any sort of gear and attach it to the lid with screws and you now have your cam follower.

 

[Les Jones]

Hi John,
You did not get me confused. I did that myself by not reading post #25 properly. This is how the cam (Disk with notch) and micro switch works. The motor is connected to a permanent supply via the micro switch. The micro switch contacts are open when the lever drops into the notch and closed the rest of the rotation. This means that the motor will stop when the lever on the micro switch drops into the notch. To start one revolution of the motor the micro switch is shorted out for a short time. This pulse needs to be long enough for the lever on the micro switch to come out of the notch but shorter than the time of one revolution. As soon as the lever on the micro switch comes out of the notch the power is supplied to the motor via the micro switch until the notch is reached again. This is the same as the method used by the feeder unit but that uses a flat on the shaft instead of a notch to operate the micro switch. Do you need any safety mechanism in case the bird is using the dish when it rotates ?

Les.

 

[KeepItSimpleStupid]

These **broken link removed** with the rubber removed and notched can act as a cam.

These **broken link removed** could be used to secure the disc/jar lid to a shaft.

 

[spec]

​

NOTES
(1) Mount the limit switch so that, in the vertical position, the bowl actuates the limit switch to take up the state shown in the schematic (12V not connected to the motor)
(2) As the minimum timer switch operation is 1 minute, the bowl will rotate for 1 minute before coming to rest in the vertical position. This will help ensure that the bowl is clear of debris, but if this is a problem a simple addition can provide one revolution only.
(3) A battery version could be configured. The battery would not need to be recharged for over a year, but a battery operated timer would need to be found. If push came to shove, a modified digital alarm clock would do the job.
(4) For safety, connect the 0V terminal of the power supply to earth.
(5) It should not be necessary, but if the bowl overruns a braking resistor/diode can be added.

 

[John R]

Hey Les I don't need any safety for the bowl as the way I will have it installed will cover any safety issues.

 

[KeepItSimpleStupid]

spec: PS: For next time: There's no 110 VAC in the US anymore. It's 120/240 split phase. 3 phase residential is available in very select areas.

 

[Les Jones]

Hi John,
Here is yet another circuit.

This incorporates KISS's suggestion of providing braking to stop the motor more quickly. The value of the capacitor may need to be changed depending on the relay coil resistance and the length of pulse required to get over the notch. (I have assumed a relay coil resistance of about 700 ohms which is typical for a small relay.) One other suggestion would be to repeat the sequence twice to wash the bowl. So the timer setting would be something like this. 07:00 motor timer switches on. 07:02 motor timer switches off. 07:03 water timer switches on. 07:04 water timer switches off. (Assuming one minute to fill bowl.) 07:05 Motor timer switches on. o7:07 motor timer switches off. o7:08 water timer switches on. 07:09 water timer switches off.

Les.

 

[spec]

Hi John,
Here is yet another circuit.
View attachment 99218

This incorporates KISS's suggestion of providing braking to stop the motor more quickly. The value of the capacitor may need to be changed depending on the relay coil resistance and the length of pulse required to get over the notch. (I have assumed a relay coil resistance of about 700 ohms which is typical for a small relay.) One other suggestion would be to repeat the sequence twice to wash the bowl. So the timer setting would be something like this. 07:00 motor timer switches on. 07:02 motor timer switches off. 07:03 water timer switches on. 07:04 water timer switches off. (Assuming one minute to fill bowl.) 07:05 Motor timer switches on. o7:07 motor timer switches off. o7:08 water timer switches on. 07:09 water timer switches off.

Les.

Hy Les,

How would the motor ever run- a slight change to relay wiring should do the job.

Bowl washing is a neat idea.

spec

 

[Les Jones]

Hi spec,
The motor is only shorted out (By the NC contact.) when the relay is de energised. The relay is pulsed on by the capacitor and diode and held on by the micro switch. If the OP new someone that could program a PIC or Atmel AVR micro the whole sequence could be programmed in. The software would not need to know the real time. It could just repeat every 24 hours. There could be a button to initially set the time of the first sequence.

Les.

 

[spec]

Hi spec,
The motor is only shorted out (By the NC contact.) when the relay is de energised. The relay is pulsed on by the capacitor and diode and held on by the micro switch. If the OP new someone that could program a PIC or Atmel AVR micro the whole sequence could be programmed in. The software would not need to know the real time. It could just repeat every 24 hours. There could be a button to initially set the time of the first sequence.

Les.

Hy Les,

I understand your circuit and about the braking. But at the moment the motor would never get powered and when the relay is energized it will short the 12V supply.

spec

 

[Les Jones]

Hi spec,
You are correct. I have drawn the circuit with the common and NC connections on the relay swapped over. The common should connect to the motor and the NC to ground. I will edit the circuit. It is drawn in pencil so it will be easy. Thanks for spotting the error before John tried to build it.
This is the corrected version of the schematic.

Les.

 

[John R]

Looks great. Ha like I would know any better I understand the PSU is power supply unit, but what is 10k, 1000 uf, IN4001. Sorry but as you know by now I'm illiterate to that these sorts of things but am learning quickly. I want to build it but just want to be sure I get the right stuff.

 

[Les Jones]

Hi John & spec,
I have just thought of another possible problem with the circuit. The problem is that the capacitor will start to be discharged as soon as the contacts on the micro switch close. It may have discharged enough by the time the full revolution has completed to hold the relay in. (Thus initiating another revolution.) I have made another change to the circuit so the capacitor is only discharged when the power is removed.

The 1K resistor across the 12 volt power supply is to discharge the capacitors in the power supply and to provide a discharge path for the 1000 uF capacitor.
Les.