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PostPosted: Tue Jul 31, 2007 12:34 am 
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Champion Bird
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I have found a design flaw in the incubator.
I am getting temp swings when the egg tray is in different positions.
The probe is fixed in the line of the pivot of the tray.
I think the problem is a combination of the fan position and the fan speed.
The fan is mounted towards the front of the bator and the airflow is straight down to the floor.
The following graph shows the swing in temp, I have also experimented with a cardboard deflector to redirect the airflow in different directions.
I will also install a potentiometer into the power line of the fan and experiment with different fan speeds as well.
Image
Comments and ideas are welcome.
Regards
Trev

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PostPosted: Tue Jul 31, 2007 3:21 pm 
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Superior Bird
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Hey chookmad,
Is this the same guy that built the first incubator. :lol:

You sure have that wafer under control.

I'm guessing that you have the probe at the eggs, for reasonably obvious reasons. You might try moving it around (including right on the wafer) to kind of plot a temperature gradient distribution.

I'd be tempted to put the probe right against the wafer and go through all the same stuff as above. The changes won't be as dramatic as above but you should see something that might help you.

You should see how even though the wafer continues to turn on and off at the exact same temperature it's own average temperature actually changes.


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PostPosted: Tue Jul 31, 2007 7:15 pm 
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Gallant Game
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Try putting your fan on an angle like I mentioned before.
When I built mine I went to multiquip & had a look at there incubators & then set mine up like theres.
Regards
Mario

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PostPosted: Wed Aug 01, 2007 12:55 am 
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Champion Bird
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G'day Denis and Mario,
Thanks to both for your suggestions, Mario I had noticed the angle of the fan in your bator, thats why I tried the deflector yesterday and it seemed to help, after this hatch I will redo the shelf to incorporate the angle fan mount.

Denis the logging is great, I havent tried the microcontroller for temp control yet as I wanted to see what this wafer is like, I think i have been lucky and got one with fairly tight swing. I installed a fan control pot into the fan power line tonight and dropped the fan speed to 3/4 of what it was (12v computer fan running on 9 v supply, now about 7v approx) The graph shows the difference that this made with no wafer adjustment.
I suspect the airflow was to fast causing temp differential zones combined with the high sides of the egg tray acting as a deflector as well.
I will let it settle and monitor and then try the probe in different positions.
Image

It has settled in since I took the above screen shot and is maintained the same level, so the difference is now about 0.2 degree compared to previous 0.75 degree.
Maybe I am being picky?
Regards
Trev

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PostPosted: Wed Aug 01, 2007 12:57 am 
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Superior Bird
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Just looking at well your going I'd save the controller for something else.


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PostPosted: Wed Aug 01, 2007 9:44 pm 
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Champion Bird
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Already chewing over in the head what the next project will be.
I've got some idea's just dont have the materials as yet.

Cheeers
Trev

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PostPosted: Wed Aug 01, 2007 10:36 pm 
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Gallant Game
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Another thing with my bator, it only has 2, 3/8 ventilation holes. both are on top. 1 is on the left hand side in the middle, half way between the shelf & top of the bator. It is on the opposite side & in line with the fan, so the fan sucks in fresh air. The other is in the same place on the other side, directley in front of the fan, which helps blow out some of the stale air. This way when the hot air goes down the bottom it just bounces of the walls & with none escaping. I hatched every fertile egg I had with my bator last season 90+ with no problems.
Regards
Mario

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PostPosted: Thu Aug 02, 2007 4:03 am 
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Superior Bird
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Something I think would be worth trying would change the board you have mounted the fan in from wood to metal. I not thinking of a reflector here but a black body.
Something that will conduct heat like a barbeque plate. This way the plate will warm up and radiate heat rather than rely on air flow all the time. But it will be quite a low heat as opposed to 1200 degs or whatever a light globe is.

I'll get a camera out and show you how I make an auto turner. If it takes me as long as 30 minutes to make one it's because I've stopped for a smoke.


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PostPosted: Fri Aug 03, 2007 8:26 pm 
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Champion Bird
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Hi Denis
I look forward to seeing the photos
Regards
Trev

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PostPosted: Sat Aug 04, 2007 7:04 pm 
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Superior Bird
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Image

OK the simple way to make an auto-turner. Basically it is a simple turntable that sits on a shelf or even the floor of an incubator. The shelf or the floor is about 20 degrees to the horizontal. I've pictured the same egg sitting in the rack twice. Once to depict what is happening when the egg is at the bottom and again when it is sitting at the top. The turntable spins every 20 mins for 10 secs. This is about a third of a turn each time. Whilst the egg doesn't move at all in the tray the embryo does move to other side of the egg like a normal tilt set up. The angle of tilt I haven't optimised or anything but the embryo moves through more of the egg white than normal tilt set up. It also "rests" in a different spot every time whereas the normal tilt will go back and forward between the same two spots.
Image

I use a BBQ rottisserie Kit to drive it. The DC kind that normally run off two "D" cell batteries. Just cut as much shaft as you need.

Image

I've used some white plastic stuff as the turntable, something like 3mm MDF etc would work too. The blue "dots" are self adhesive plastic thingos used for legs of furniture to make them slide easier. I do this because I'm too lazy to countersink my screws and this way the screw heads aren't catching on the mesh.

Image

I use a rubber grommet to grip the shaft. Bad idea. The shafts usually have a squarish crossection so just cut same in your mdf and it will drive without slipping.


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PostPosted: Thu Oct 04, 2007 8:43 am 
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Hi All,

Just a little update on what I have been up to. I have built an incubator box similar to the one at the start of this thread and it is populated with:

Heating element which came from a curling blow hair drier. This is only 250 watts at 240 volts and bought for pennies off Ebay.

A temporary relay thermostat (Vellerman Kit) running at 12 volts DC from:

http://www.maplin.co.uk/Search.aspxcrit ... ce=15&SD=Y

I did have to change the thermistor to a 15k one to get it to work at higher temperatures. The relay is only rated for about 24 volts but who's counting and do I care if I only get 500 thousands switchings instead of the rate million. Because it has a relay for switching it is refered to as a bang thermostat and I am looking into a design for a Pulse Width Modulated progressive one which should solve the other quirk in that it has a 3 degree F gap between on and off. This temperature fluctuation is roughly similar to the Ecostat 60 round green semi auto I have been using, which will find itself on Ebay soon. I have it set at a mean temperature of 99.6 F

There are also 2 fans, one before and one after the element, which came from computer power supplies and these also run at 12 volts. These are angled so one powers warmed air into the egg chamber and the other drags cooled air from the chamber and forces it through the heater. Dispite this the element still switches out via it own overheat protection bi-metal switch so is not constantly on during the heating cycle. Clearly there is a need for more airflow but I'll address this when I build the progressive controller.

Humidity is a constant 40% and if I add a small tray of water it goes up to 70% within a few minutes.

Egg turning is automatic using plastic eggs trays obtained from:

http://www.solwayfeeders.com/

and a frame fabricated from aluminium sections obtained from B&Q Warehouse (a DIY chain store here in the UK), they were expensive and bought for another job which never happened. I have since found them to be available from many metal stockests and much cheaper.

The turning mechanism is an off the shelf DC motor and gearbox part number SN36P from:

http://www.maplin.co.uk/Search.aspx?cri ... P&DOY=3m10

This was driven by a speed controller kit from:

http://www.quasarelectronics.com/3067.htm

I then fitted a pair pulleys and belt with about a 4:1 step down ratio and a crank to the egg turning frame shaft which comes out the back of the incubator box.

This combination almost did the job but the gearbox shaft bent with the tension of the belt and I couldn't get the motor speed low enough and still get reliable turning without stalling. I then fabricated another thicker shaft which is driven by a 48 dp 48 tooth gear off the gear box giving a further step down and this did work. It now rocks the eggs trays (there are tow holding 160 quail eggs) through about 70 degrees once every 30 minutes.

The incubator is now stocked with 60 eggs and has been running all night. I am crossing my fingers all will be well while I collect data over the next few weeks and set to building an improved thermostat.

My next project will be automatic humidity control and then a few more weeks collecting data.

Then it will be small stepper motor for the turning and the big cheese, microprocessor control of all functions.

If anyone wants photos it will take me a couple of days to sort it out.

Regards, Terry


Last edited by wotisname on Thu Oct 04, 2007 10:57 am, edited 1 time in total.

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PostPosted: Thu Oct 04, 2007 10:03 am 
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Discerning Duck
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Come to think of it, my bater has the heat comming from the top too, and when I put an extra water tray down the bottom it was stone cold as well.
How come were not making the heat come from the bottom of our home made baters ? as heat does rise.
Might have to make another one.

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PostPosted: Thu Oct 04, 2007 10:45 am 
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Hi kazlee,

I reason why I built mine with the heat on top is because I wanted a tray in the bottom as a hatcher. The last thing this would need is hotter air than the incubator temperature blowing through it. With the heat on top the egg incubating temperature is set at the egg level, so the bottom should be that little bit cooler needed for hatching.

Incidently I put the tray of water, mentioned in my post, directly under the heating element and in the airstream, not in the bottom where it would indeed evapourate much more slowly and not be as effective.

Regards, Terry


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PostPosted: Thu Oct 04, 2007 11:03 am 
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Superior Bird
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The cold water at the bottom is something I have had. As long as the eggs are at the right temperature a colder water tray just means you need a bigger tray to achieve the same humidty.

One reason I can think why electrics up the top and water and chicks done the bottom is to lessen the chance of spillage of water into the electrics. But that's probably the only reason. I've done incubators with the heat up the top, at the sides, at the bottom and the latest has heating both top and bottom. The one with the heat at top and bottom has hatched 6 or 7 chicks this morning with the eggs sitting right on the floor.

Kazlee, you might find it easier just to move your water tray up near the top of your incubator.


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PostPosted: Thu Oct 04, 2007 11:24 am 
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Discerning Duck
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Hi Denis, The water tray is up the top, but on the last hatch, we had really windy dry weather, why it made a difference I don't know, but I couldn't get the humidity right. I find I don't have that problem when it rains :?
Once I get aoout ten chicks hatched I start taking them out of the bater and put them in a box of straw with a bunny rug over them, I find they fluff up quicker and are a lot happier, no crying at all. And you get less fluff in your bater.
That also gets rid of the need for a hatching tray.
I think your right, the main reason the heat isnt on the bottom is for safety reasons. If I put my mind to it ,I might be able to get around that.
Looks like i'm back to the drawing board. :D

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