Introduction: Small Incubator With Temperature Controller

We have a few chickens at home but we wanted some more so we chose the ones we wanted and decided we wanted to hatch some eggs. Unfortunately for me this meant that my dad now want an incubator so i had to build him one. all in all this project cost us less that £40 and works wonderfully considering that a shop incubator can cost £100s. It was built out of a 450mm x 350mm polystyrene food box and can incubate a maximum of 8 eggs at a time. I used mainly wood and materials that I had lying around my workshop. 

The temperature controller is based around a digital temperature controller and has a dual output of either 240v or 12v this is so i can run my incubator and my wood kiln from the same box.

You will need:

1 - polystyrene box of at least 450mm x 350mm
2 - 185mm x 245mm x 20mm MDF
2- 65 x 245 x 20mm MDF (although I used 16mm)
2 - 105mm x 185mm x 3mm MDF 
2 - 120mm x the width of your box x 20mm pine (not MDF as it will fail with the humidity)
1 - 85mm x 85mm x 20mm pine
1 - 85mm x 85mm x 3mm MDF
3 - 240mm long pieces of pipe insulation
2- 20mm diameter pipe the length of your box
1 - 20mm diameter pipe 13mm longer than your box
2 - 

2 - IEC sockets 
2 - 10a, 240v, DPDT toggle switches (or rocker switches if you prefer) 
1 - 1/4 inch mono jack socket
1 - 1/4 inch mono jack plug
1 - 1/4 inch stereo jack socket
1 - 1/4 inch stereo jack plug
1 - 240v to 12v transformer (I used an old laptop power supply)
1 - peltier cooler -
1- computer CPU heatsink and fan
1 - heatsink paste
1 - assortment of cables and wire
1- digital temperature controller - 

Soldering iron and solder
drill and drill bits 
hacksaw blade
bandsaw (optional)
mitre saw (optional)
pipe cutter
router table (optional) 

Step 1: - Heater

For this I decided to use a peltier cooler and an old computer CPU heatsink. A peltier cooler gets hot on one side and cold on the other to find out which is which then attach it to a battery and feel each side one should be hot and one should be cold.

You will need the cooler which i found here -

I also had a small tube of heatsink paste, which i used. I would strongly recommend using heatsink paste as it improves the transfer of heat so you'll get a more efficient heater but it also holds the cooler to the heatsink. If you don't have a heatsink and fan there is sure to be one on eBay. 

Step 2: - Layout

Draw out where you want all your parts to be i did mine 1:1 on a piece of A4 when i had al my parts together this meant i could visualise where everything will be on the front and back, I also started to think about the wiring and how it was all going to be laid out inside the box i started with the front measuring all the components and drawing it out on the front of the box then deciding what will be on the back of the box. 

The back of the box has two IEC sockets one for 240v in and one for 240v out it also has a jack socket for the temperature robe and another for the 12v out.

Step 3: - Box

Cut out the 2 - 185mm x 245mm x 20mm MDF the 2 - 65 x 245 x 20mm MDF and the 2 - 105mm x 185mm x 3mm MDF assemble the three sides of the 20mm MDF together with screws then mark out the front panel and cut it out, for the temperature controller hole i drilled out most of it with a 20mm forester bit and then filed it straight with a flat wood rasp, the temperature controller i used came with two nice orange clips that held it onto the face of the board then either side I drilled two holes for the switches. 

The same is true for the back panel I marked out the IEC sockets and drilled the holes for the jacks, then made it straight with a flat rasp, whilst the panels were on the pillar drill I drilled and countersunk the screw holes.

After this has been done you can put all the hardware into the holes and screw them onto the 3 sides of the box using the appropriate screws.

Step 4: - Electrics

This took the most thought for me although should be easy if you have a basic electrical knowledge.


Before we start always tin wires and lugs this means better electrical contact and its also easier to solder it together, if you don't know how to tin here is a good guide.

First you want to get three lengths of flex and attach two to the live and neutral of the bottom IEC socket, this will be the 240v in, then you want to take the live from the IEC to one of the two middle lugs of the switch then you want to solder another wire to the bottom lug of the switch but make sure it is on the SAME side the put the to in to a junction strip, the strip is about 30mm from the back of the temperature controller when it is installed. Now you have a switched live

Then you want to attach the input to the transformer to the bottom two lugs of the second switch, this will switch it from 240v to 12v, (if you don't want the choice you can attach the transformer straight to the other side of the junction strip), then put neutral on the left as in the second picture, I always have it on the left to make the wiring easier for myself. The you want to take two wires out of the back of the junction strip and attach them to the middle lugs of the switch again keeping neutral on the left.

Now you want to put the temperature controller in and take two more wire out of the the junction strip and put them into the power input on the controller in my case 3 and 4 this will mean that the controller will always be on no matter what the position of the second switch.

Then you want to attach the output leads of the transformer into a junction box i had 4 a 12v and a 5v but if you only have 2 it is the same process prior to this I plugged in the transformer and found out which lead did what the right two are positive and negative 12v. This is shown in the sixth photo I switched the live wire but you could just as easily switch the neutral. The live (white) wire is connected to the relay i used a junction strip because I also wanted to put 240v through it. Then take the neutral wire and attach it to the neutral lug of the stereo jack socket in my case it was the middle one but when you look at it side on it should be divided into three layers the top layer will be the neutral layer. The 12v output form the transformer is the switched one and this is attached to the lug on the second layer of the output jack the put the 5v onto the third lug of the output jack, it doesn't matter which ones the 12v and 5v are on but the neutral must be on the correct one.

If you only have two leads it is the same process although you'll only need a mono jack socket and the negative attached to the ground lug and the 12v attaches to the other lug.

now you should be able to power it up you'll get EEE on the front as you don't have a temperature probe attached. set your multimeter to 20v dc then place the negative probe of the multimeter on the large metal lug on the plug and then the positive probe on one of the two others if it reads 5 it is the 5v output if it reads 0 it is 12v output (this is because the 12v is attached to the relay and will only give an output when the relay is on). Then solder a length of 3 core flex to it, I used green and yellow for neutral, brown for 12v and blue for 5v

then take the neutral wire from the top of the second switch and solder it to the neutral lug of the IEC socket then take the live feed from the switch to the right side of the junction block then take a cable from the left and solder it to the live of the IEC socket.

then you want to take your mono jack socket and solder on two wires and put them into the temperature probe in on the temperature controller (it doesn't matter which way round they are

then solder a length of two core flex (i used xlr cable because i had that lying around) and solder it to the two lugs on the mono jack and solder the other end to the temperature probe and be sure to insulate, I used some heat shrink tubing.

then solder the other ends of the 3 core flex you previously soldered to the stereo jack plug and solder the negative to the negative and the 12v to the heater and the 5v to the fan.

and you are done with the electrics take a break and rest your head have a cup of tea the rest is a lot less difficult.

Step 5: - Egg Turning

for the turning mechanism I cut 3 240mm long pieces of pipe insulation the insulation was about 4mm to large in internal diameter so i had to cut a small wedge out of the side to make it fit i then cut two pieces of pipe that were 2mm shorter than the box and one that was 13mm longer.

I then cut two pieces of pine 120mm high and the width of my box, I then marked a line 100mm from the bottom and then marked the centre and 70mm either side, this is so the elastic bands that are used to drive the two on either side would be tight. I then drilled the holes with a 22mm forester bit and slotted everything together. I put a bead of silicone in the slit i cut and held it together with cable ties and jubilee clips (i ran out of cable ties) 

Step 6: - Side Vent

First I cut an 85mm x 85mm square piece of 20mm pine and drilled a 58mm hole in the centre with a forester bit, then I cut an 85mm x 85mm piece of 3mm MDF and rounded three of the the corners off with the lid of a glue stick leave one corner un rounded as this will be the one that you attach it with. Then cut off the corners, I used my bandsaw but you can use anything. After that  give the top of the MDF a sand with some 120 grit to remove pencil marks and the shiny surface, and also to smooth the corners off. 

Then drill a hole 10mm in from each side of the corner you didn't round and then drill a hole that is at least 1mm bigger than the diameter of screw that you are using, my screw had a 3mm diameter so i drilled a 4mm hole and countersunk it, this is so the top piece can swing freely on the screw. 

As it swings freely you'll need a way to stop it from opening all the time so I drilled another 4mm hole randomly but a better place is diagonally opposite as you can drill a series of holes to hold it open at different points, I only had three. Then you want to cut a short length of solid core wire (not flex) and bend it into a 'P' shape by holding it in some needle nose pliers to bend it. Then you want to cut out an 85mm x 85mm hole in the polystyrene box. I first drilled it with the 58mm bit then made it square with the rasp, this bit gets very messy and the polystyrene beads get everywhere.

Now you want to push fit the vent into the side luckily mine was tight as I filed it to slightly under 85mm then you want to put a bead of silicone around the inside this is just to stop any more air gaps than you need.

Step 7: - Viewing Panel

You want to be able to see when the eggs are hatching without loosing all the heat so I cut a rectangle about ... I cut out most of it with a hacksaw blade and then made the edges straight by putting it on my router table and using the fence the guide it straight. If you don't have a router table then you can use the rasp to flatten it, it works just fine, but the router table is quicker so thats what I used.

Then I cut out two pieces of clear acrylic that were 20mm bigger on every side and then just secure it down with a generous amount of silicone, I used silicone mainly as I knew that it wouldn't react and melt the polystyrene. After you put on the first one you can turn it over and put on the second one to make it double glazed this massively reduces heat loss from it so I highly recommend double glazing it. 

A little hint when using acrylic, cutting it can build up a static electric charge in the acrylic which loves the small little poly beads so just rinse it under some water (or dunk it in a water butt a few times) and let it dry naturally, don't manually dry it as this can build up the static charge you've just dissipated in the water.

Step 8: - Hatching

you are now done you will want to put a small dish in the bottom with a sponge in it to control the humidity you might also consider one of these so you can monitor it, an RH of 58% - 61% is said to be optimum but values vary for different type of eggs so research for the bird you'll hatching. 

Set the temperature to around 37 -  38 degrees centigrade although if you have one like mine set it for 38 as it will lower a degree before coming back on again. 

you could also add a 1 rpm motor to turn the eggs but i was on a strict deadline as the eggs had arrived and had a day to make this and so i couldn't get one in time. 

I will be entering this into the Hurricane Lasers contest and if I win I will do a whole heap of instructables including a wooden childrens lighthouse dollhouse and a super secret safe box. so vote for this because in 15 and built this in a day.
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