[amdtoad]

hi joy your right a broody hen is best, but this thermostat i got is very very stable on 37.5 degrees c with no unstable shift, which is great, but when the incubator has been on for about a hour, the relay starts making a arcing noise, which should be just a click when off and a click when on, i have just picked up a 12volt 1500ma regulated psu, in B&Q DIY old stock boxes or junk box, they were only £3.00 each and still in the packet, so i will give that a go, may be the mk138 thermostat kit dont like switch mode power supplys for some reason,

kind regards

shaun

[Chookiechook]

Hi....

Been there and done that and got thoroughly bored of all the problems and failures

Made a bator out of a poly fish box... bought the maplins kit.... wired it all up and it blew so obviously did it wrong.. but still a waste of money......

To be honest..... I would go out and buy the best you can afford in the autumn.... second hand is fine.... and then when finished you can sell it (in the spring when people get silly money for bators) and not lose any money and get fab results in the process.


Suros and octogons are cheap and efficeint and you will get your money back when you sell it on


I have got a purpose built Hovabator which despite being built by professionals is still dodo   so how can we hope to better them

[amdtoad]

i found the problem with the velleman mk138, i change the R7 resister from 10m back to the 6m8 what came with the kit, now the relay chatting has stop, and its running perfect thermo and hygro, when i had taken my radio amateurs exam, its good practice to build much of your own radio equipment, its allways possible to build your own, when it comes to electronics, not just short cut and go to a shop because you fail, ok sometimes we all ask for help with topic at times, but never fail, i was a complete retard at school, i ended up at a special school, but anyone can make it in the world,

cheers shaun

[hillfooter]

Firstly this is a really interesting project not without some really practical design challenges so well done for taking it on however there are a lot of substantive issues here not just electronic ones.  You presumably want to do this for the challenge not just to get a cheap incubator (which I doubt you'll acheive to the extent of justifying the effort.)

Speaking as an electronics design engineer and chicken keeper the following is a critique of your design parameters, a sort of concept design review if you like.  The sort of procedure you might expect to have in a real engineering project so don't be put off by the fact there are a number of issues I've raised.  You need to satisfy yourself these aspects are covered not convince me or anyone else who comments.  So here are my comments take them as a gift.

I'd prefer to use a heater element rather than a light bulb.  A heater can be more distributed rather than a point heat source, like a light bulb, which will make keeping the temperature evenly distributed much more difficult.  I'm not sure if you can still get adhesive heating elements intended to stick to windows to prevent condensation but they would be ideal.  Also (having been a designer in the process control industry) I'd prefer to use proportional heater control rather than bang bang (on, off) particularly if you are going to use a light bulb it might end up being a flashing disco machine otherwise.  If you still want to use a simple thermostat you will need to use a heating element or at least an infra red bulb to stop the flashing effect. Your temperature control needs to be reasonably precise and although I totally agree with the comment about hysteresis from a technical perspective,  having a temperature sawtooth of more than 0.2 degC or so will impact your results.

A high speed PC fan will be too powerful for the air stirring you need.  You want to stir the air not have a howling gale which will produce an enormous drying effect on the eggs and result in them losing too much water too quickly.  The air speed needs to be quite low around the eggs and it needs to surround the eggs not just blow across the tops.  Hence the egg tray needs to be perforated and also allow air flow from underneath.  Your humidifier is best situated under the egg tray too.

I don't see any provision for turning the eggs at least three times every 24hours.  Doing it manually is a bit naff when you have taken a lot of effort to build everything else to be automatically controlled.  Consider a rocking cradle or at least an octagon design which can be rocked through 90deg manually It must hold the eggs without them rolling about when turning.  Actually it depends to some extent on the number of eggs you intend it to be used for. The lower the number the more practical is manual turning but consider you need to attend this constantly and not forget to do it or your results will suffer.

Humidity seems to be very much an after thought in your concept design and this is a mistake.  A simple manual system is fine and I wouldn't bother with trying to make it automatic which will be too complex.  I wouldn't even consider measuring it as cheap hygrometers are so inaccurate to be totally useless.  Far better to calibrate it once built by measuring a test egg and a trial and error approach.  Don't forget what you are actually trying to achieve is moisture loss so the egg has even weight loss through incubation and optimum moisture content at hatch.  Humidity control is the means to do this not an end in itself ie it's not like temperature which needs to be at an absolute optimum level.  Using a test egg trial and error calibration is the only way you can reasonably know how drying your system will be as it is too complex to analyse theoretically.  You will, I feel, need more humidity than an eggcup can provide and a reasonable reservoir will be needed which is quick and easy to top up and a consistent evaporation system using evaporation pads perhaps, as you need to raise humidity to 70% ish 3 days prior to hatch.  Ambient humidity might just be about OK for the first 18 days if not too dry.  You control humidity by varying the evaporation surface area and the ventillation from the chamber.  A variable entry port vane is the usual method in a forced air system.

There are a number of very important practial issues such as being capable of being cleaned and sanitised. You don't want to design a one off use box and neglecting this aspect will result in subsequent hatches being ruined by pathegens contaminating the eggs if it can't be cleaned and sanitised thoroughly.  To do this the 'box' interior needs to have a hard non absorbant surface which can be washed.  It needs to act as a a brooder too for about 24 hours during hatch so must be suitable for chicks as well as eggs.  Access is important too and needs to be ample and easy to do without dismantling the electronic system so your mechanical design is every bit as important as the electronic side if not more so.  This seems to have been neglected in your write up which has lots of detail of the thermostat design and none or very skimpy on the mechanical aspects.

To produce a design which is as refined as a commercial one like Brinsea or RCom will be a challenging and interesting project and not just an electronic exercise.  I assume that the project aspect is at least a major part of the motivation for doing it because otherwise, if you just want a cheap incubator which will hatch a few eggs without a guarenteed high success rate, you could just use a cardboard box with an infrared bulb and a lot of patience and a trial and error approach!

Best of luck.  I'll be interested to hear and see how you get on and your results with using it for hatching.
HF

[Zeph]

Hi,

Just bought all the bits to give this a go, the 1K resistor I got to replace RV1 is a horizontally enclosed potentiometer, Maplins code UH00a, check the resistors that you get from Maplins as well as 3 of the ones that I was given were wrong.

[Zeph]

Just completed this and it's holding a steady 38.5 degrees, but the light is going on and off every 5 - 10 seconds ! is this right ?

[hillfooter]

Just completed this and it's holding a steady 38.5 degrees, but the light is going on and off every 5 - 10 seconds ! is this right ?

Read my post para 3.  I think this is what i predicted.  Not only will it be a flashing machine but the light bulb won't last long being switched on and off continuously.  I suggested a heater or an infrared bulb used with proportional control so that it isn't driven on off but the heating is proportional to the deviation from setpoint.  This way the bulb won't be over stressed.   However this form of control is more complex than a simple thermostat.  On balance I'd use a heater.  A bulb is a radiant point heat source at over a  thousand degC whereas what you need is a large area and cooler heat source which will warm the air directly.  For example on a hot day the air temperature can get quite hot but it isn't heated directly by the sun.  The sun heats the ground through IR radiation and the air is heated indirectly by the ground.  If you allow an IR bulb to shine on the eggs and stir the air the air temperature may be a perfect 37.5degC but the surface of the eggs maybe much higher and a temperature gradient will exist across the egg.  To use a bulb it needs to shine on a heat sink like black painted alluminium plate with fins and air needs to blow across it's surface so the eggs are heated by the warmed air not via a radiant source like the bulb directly.  There needs to be consideration for bulb failures which will be frequent with switching and a redundant (two bulbs) system is at least required unless you want to risk the loss of an incubation.

HF

[Zeph]

Thanks, for the reply,

I've managed to slow the switching on/off by placing a couple of bottles of water in the box.

I have a small fan from an old PC and should be able to wire it up along with the cooling fins from the CPU.

The bulb I'm using is 10w 12v, it takes about 5 minutes for the temperature to get back to 38.5 when the box has been opened so i'm not sure if it will be able to get up to temperature with a fan.

I've orders some bulbs from Ebay so will try with two or more lights in case one blows.

I've read on another forum that it's possible to wire up a normal 240v bulb with this thermostat, on the Velleman forum they reckon the relay can handle 240v but hte pcb can't.

I found this picture of the thermostat, but the description of the wiring looks wrong, surely the Brown wire would be +ve ?

Just completed this and it's holding a steady 38.5 degrees, but the light is going on and off every 5 - 10 seconds ! is this right ?

Read my post para 3.  I think this is what i predicted.  Not only will it be a flashing machine but the light bulb won't last long being switched on and off continuously.  I suggested a heater or an infrared bulb used with proportional control so that it isn't driven on off but the heating is proportional to the deviation from setpoint.  This way the bulb won't be over stressed.   However this form of control is more complex than a simple thermostat. In balance I'd use a heater.  An bulb is a radiant point heat source at over a  thousand degC where as what you need is a large area and cooler heat source which will warm the air directly.  For example on a hot day the air temperature can get quite hot but it isn't heated directly by the sun.  The sun heats the ground through IR radiation and the air is heated indirectly by the ground.  If you allow an IR bulb to shine on the eggs and stir the air the air temperature may be a perfect 37.5degC but the surface of the eggs maybe much higher and a temperature gradient will exist across the egg.  To use a bulb it needs to shine on a heat sink like black painted alluminium plate with fins and air needs to blow across it's surface so the eggs are heated by the warmed air not via a radiant source like the bulb directly.  There needs to be consideration for bulb failures which will be frequent with switching and a redundant (two bulbs) system is at least required unless you want to risk the loss of an incubation.

HF

[hillfooter]

Try also improving the insulation which should slow down heat loss and reduce the switching frequency but ensure there's some ventillation too.  You can't have a completely sealed box.
HF

[Zeph]

Just a quick update !

I set 15 Chinese Painted Quail eggs in this incubator and so far have had 1 hatch with 5 pipped.

Today is day 16 so with a little luck more will hatch !!!!!

[hillfooter]

Just a quick update !

I set 15 Chinese Painted Quail eggs in this incubator and so far have had 1 hatch with 5 pipped.

Today is day 16 so with a little luck more will hatch !!!!!

Isn't this a little early though I'm not familiar with quail hatch times?
HF

[Zeph]

No, from what i've read chinese painted quail incubate in 16 days.

So far I have three that have hatched, 2 are doing really well 1 has not fully absorbed the yolk sac and isn't looking to good, whilst another three eggs have pipped. 3 candled clear after 10 days and were discarded (when opened there was no sign of development).

I'll give the others a few more days and see what happens.

Thanks