Egg Incubator

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A few weeks ago I made a chicken egg incubator with some scrap wood, a light bulb, and water heater thermostat. It worked, just not as nice as I wanted, I was in a rush.

I have been researching/designing a avr controllable incubator. No real need just a want and a challenge.

I am roadblocked at figuring out the heating element. I was thinking of using a PID controller to vary a PWM signal to a solid state relay that switches a 100-250 watt AC heating element.

I know I can use a PID controller to vary a PWM signal. I know I can switch the element on and off with a SSR. What I don't know is if I can use them together.

Would a DC to AC SSR chop the AC sine wave properly?

Is there a better approach?

I am not encumbered by the restraints of the adult mind.

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I do not know if the heating element will like chopped AC sine waves.
As a PID regulator has to be adjusted to work correctly, you could just use a SSR and a couple of temperature sensors ( that you need anyway )
you have to run experiments on when to switch ON the controller to have a certain temperature and then how long it has to be on to get hot and a check on how fast it will heat up the environment + how long it keeps heating after you switched it off again.

will be a challenge, but if you first characterize the system then making a control for that should not be to hard. ow and don't forget the outside world to as this will influence the heating.

1)Datasheet and application notes checked?
2)tutorial forum
3)Newbie start here

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I built one a few years ago with mega32 AVR. It works quite well.

I used opto-coupled zero cross control on the triac with PWM over a 2 second update period. It varies 0 to 120 cycles "ON" with 60 Hz line input. Control is P-I with some tweaking on "I".

I used a LM92 to monitor air temperature, it is SPI. I think the raw count was around 600 for 99.75 degrees F. The sensors vary some so you will have to calibrate. I used cheap oral thermometer. The temperature is fairly critical. Temperature is dropped about a degree, and more ventilation and humidity added when hatching.

I used a strip plate heater in the bottom, on an aluminum plate, with a bi-metallic cutout switch from a dryer on the plate as a safety.

There was a circulation fan, and a small amount of ventilation and water tray. Rotation was manual 3 times a day. The eggs placed in screen racks with dividers.

I also had an LCD to monitor control variables. I can share code if I can find it.

There may also be a post somewhere here.

It all starts with a mental vision.

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It all starts with a mental vision.

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I plan on using a Honeywell HIH-6130. It uses I2C, 14bit ADC resolution, and sensor calibration is easy. It cost $15 at mouser, but its a temperature and humidity sensor combined.

Humidity will be controlled with a DC water pump, in an external bucket, that sprays water through a mister nozzle.

I plan on having servo activated air vents, auto egg rotation, a circulation fan, door switch, and an alarm.

An LCD on the I2C bus will have a menu for choosing incubation settings for chicken, turkeys, ducks, quail, etc. As well as display pertinent information current temp, humidity, time till hatch, errors, etc.

I am not encumbered by the restraints of the adult mind.

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@KitCarlson

KitCarlson wrote:
I used opto-coupled zero cross control on the triac with PWM over a 2 second update period.

Admittedly I am a CS not an EE. My EE skills are self taught and generally low volt DC.

I essentially want to control an AC heating element like you would with a dimmer switch.

As I understand the way a good dimmer switch works is that it turns off the AC when crossing the x axis and back on at some point proportional to where the switch is, so twice during one period.

Does your solution factor that in? Or is your period long enough that it does not matter?

I am not encumbered by the restraints of the adult mind.

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This egg rotation surprises me, does that happen in nature? I thought the eggs just sit there with momma on top.

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dksmall wrote:
This egg rotation surprises me, does that happen in nature? I thought the eggs just sit there with momma on top.

Yes. The hen will spin the egg several times per day.

Most people when doing it by hand in an incubator will put an X on one side and an O on the other.

Automated turners orient the egg small end down in a sort of egg carton and rotate them back and fourth from +-45deg

The point of it is so the chick does not get stuck to a part of the shell. If that happens they can be deformed or die.

I am not encumbered by the restraints of the adult mind.

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Quote:

I essentially want to control an AC heating element like you would with a dimmer switch.


Quote:

Or is your period long enough that it does not matter?

Indeed you could perhaps/probably "feather" the heater as with a dimmer. The real EEs will need to comment on possible heat considerations in the dimmer itself.

However, many/most heating situations will have a quite long "time constant". While P-I-D concept/approach can certainly be used, you may well find that just a common-sense approach using the concepts and information about the actual device will be simple and effective. For example, getting to desired temperature from room temperature when setting up isn't a big race. Steady-state shouldn't have many disturbances. Perhaps the biggest will be from inspection/rotation?

I'd wager a virtual cold one that you'd find that having a smallish heater on for a few seconds out of 50 or 60 would work well. (But I don't know the effects of the venting/circulation.)

You can put lipstick on a pig, but it is still a pig.

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So the mother hen worries if her chicks are sitting bigendian up or littleendian up. The ones that develop upside down grow up to be Intel programmers. The others Motorola.

Imagecraft compiler user

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bobgardner wrote:
So the mother hen worries if her chicks are sitting bigendian up or littleendian up. The ones that develop upside down grow up to be Intel programmers. The others Motorola.

:D Funny stuff

I am not encumbered by the restraints of the adult mind.

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