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Hi Chiba,
Many thanks for that. I had a look at that one on ebay. No details are given and I think it would be too small to do the job in hand.Besides I would like the pleasure of having built the unit myself.
Hi Chiba,
I am only hatching chicken eggs not dinosaur.I could not get any details of that small unit on ebay.I do not know where you came up with the 2500W.
He got that from the relay contact rating. If it is able to switch 250V @10A, then thats 2.5kW. Although that is a 'maximum' rating, so one shouldn't really hit the limit.
I assume it is simply the controller? That isn't the heatter itself, a 'thermostat' is just that, a temperature sensor which turns a heating appliance on and off, to keep the average temperature within a tight range. What heater you usewith it, is up to you.
I'd like to ask a few questions like:
1. What is the heating element size (Watts)
2. What is the space size
3. What are you going to use for a heating element.
4. Voltage (OK, you said 240 V)
The next thing I need to talk about is the output type. Is it going to be bang/bang or ON/OFF control or variable such a ZCPP (Zero crossing pulse) or (Phase angle fired). The latter assumes AC
Phase angle fired essentially applies a slightly varying voltage. ZCP applies an number of line cycles and ON/OFF control is usually useless
Usually temperature controllers are PID or (Proportional, Integral and differential) These constants effectively make the temperature and setpoint agree, manage overshoot and applied power.
Hi, I am using a proper incubator housing measuring 18 inches across and 5 inches high.It was originally an off market incubator for 24 chicken eggs.It will be fired by a 240v 40 watt globe,using a 12 volt fan for circulation. I am not very technical but I think that PID is the way to go.
Thank you.
You really don't want to have a blinky bulb, so I think you need phase angle firing. This SCR Power Controllers for Electrical Resistance Heaters is just the device that controls the power to the load, not the temperature controller. The standard output signal from a temperature controller is 4-20 mA which is fed to this device to control power.
You do need soft start or current limit because the light bulbs filamant resistance when cold is about 10-15 times less than when it's hot. The fuses that protect the semiconductor are I^2T and are expensive ($15-30) each. You would need something rated for 10 amps minimum. The use of a smaller fuse (say 3A slow blow) in your case in series with the semiconductor fuse can also be beneficial. If sized right, the cheap fuse blow first.
My favorite temperature controller is Eurotherm. The amount of settings that are on their controllers are enormous.
You also need a sensor that, I think needs to measure air temperature. RTD's are the most accurate. Thermisters may be appropriate here. A "T" type thermocouple is best for temperatures near room temperature.
Omega is a "one stop" shop. They tend to re-brand what they sell.
If the eggs can benefit from a programmable temperature profile, then controllers can have that ability too.
Hi,
I really appreciate your input and your willingness to help.As I said before, I am not a very technical person and I need to keep it simple as possible.
Thank you.
Hi, I am using a proper incubator housing measuring 18 inches across and 5 inches high.It was originally an off market incubator for 24 chicken eggs.It will be fired by a 240v 40 watt globe,using a 12 volt fan for circulation. I am not very technical but I think that PID is the way to go.
Thank you.
Just out of curiosity is this going to be a commercial type project or more like a one time science experiment? Your heat source is a 40 watt incandescent lamp at 240 volts that will draw considerably less than one amp of current. You plan on forced air flow. Do you have any plan or consideration for RH (Relative Humidity) and if so how do you plan to measure it? Will you be rotating the eggs manually on a daily basis? Will this incubator sit in a room with a real stable ambient air temperature?
If this is going to be a one time science experiment there are cheap and simple ways to go about it. If, however, you want to begin commercially hatching eggs there are other ways to go about it. Do you have any kind of budget in mind? The budget is a real big factor in this project.
For this to be done its not all that big a problem, I incubate reptile eggs which sometimes have a tolerance of about 1C either way, I have made my own thermostat do exacly what i want it to as the ones on the shelf are pants. The thermostat i have is Pulse Proportional, it has a setpoint and then the heaters job is to match the setpoint, as the temperature increases the heater will begin to turn on and off it is done in a series of pulses, sets of 5 for 1 second per pulse, (eg: off,on,on,on,on) as the temperature gets closer to the setpoint the off pulses get longer (eg: off,off,off,on,on) this pattern just fluctuates nicely when it reaches a sort of happy medium. This takes care of overshoot and hysterisis is minimal.
Doing this is easier than using phase angle, and better accuracy than relay operated thermostats.
Humidity can also be factored in the same way as heaters, all i do is set it to mist the enclosure every 5 mins depending on the actual RH, due to the nature of RH it takes a while for reading to emerge, i.e spraying the tank doesnt give instant results, it takes a few minutes to get an accurate readout.
If your incubator is a pro egg hatching type it may already have a egg turning mechanism built in, iff not this can be acheived quite easily also.
Hi Cobra1
Your thermostat seems to be the ideal thing.Is it possible to view the circuit?Regarding humidity in the incubator I have in the past relied on the presence of water in the enclosure..Hot air and water cause humidity.Of course it would be much better if humidity could also be factored.One would get better results.Regarding turning the eggs I do so manually three times a day.
Thank you
Hi Ron,
Thanks for your input.This is only a hobby of mine.I have my incubator in a very quiet room in the basement.Regarding humidity I depend mainly on the presence of water and moving hot air in the incubator.
My thermostats 'circuit' is on 4 PCBS. It has a power supply, mains switching board, Sensor board (sensors etc), and an LCD module PCB, aswell as that it has 2 smaller boards that connect to the LCD module for capacitive touch panels.
If its just the temperature and humidity you want to regulate then send me your email address and i will send you a pcb design for an older stat i was working on, it has more features available than you require but you can just use from it what you need.
It will need some software writing for it too as i lost the files for it when my computer through a wobbler.
Hi Ron,
Thanks for your input.This is only a hobby of mine.I have my incubator in a very quiet room in the basement.Regarding humidity I depend mainly on the presence of water and moving hot air in the incubator.
If the ambient temperature is pretty stable in the room I would just get a common cheap lamp dimmer switch and try to find a "sweet spot" where with airflow at a constant you can maintain your 100 or so degrees F.
Another option would be to take cobra 1's kind offer.
I would not look to get too fancy (expensive) with a simple home project / experiment.
There is one more option, if you look on the net and look for a microclimate thermostat, either pulse proportional or dimming, (pulse proportional cant be used with light bulbs) (dimming uses phase control and can be used with light bulbs)
These thermostats are used for reptiles which demand a much better control of temperature. Using one of these thermostats will get you a very stable temperature. The price ranges from £30-£60 depending on where you go. but then the work is already done for you and gets you sorted quickly.
Hi KISS,
This building of an incubator thermostat is becoming rather complicated. I have considered using a circuit built around an IC CA3059 but the latter is hard to come by locally.Perhaps there is someone out there who may know where I can get one.
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