Me and my dad needed a way to start some plants in the middle of winter and this is what i came up with with most of the parts coming from my garrage and around the house. This is my fisrt instructable too, so lets hope it turns out good.
Step 1: Parts
A 12 volt computer fan
Some kind of heater with a thermastat (I used an old water bed heater i had lying in the garage)
A 12v dc power supply (Mine used to be used for outdoor lights, even had a timer on it!)
2 1 watt 100ohm resistors not pictured
1 1/2 watt 470 ohm resistor not pictured
4 red super bright leds not pictured
1 blue super bright led not pictured
Small storage box
Step 2: Install Fan
i put the fan were i wanted it traced it on the inside and cut out with a jigsaw. Then drill the four holes for the screws and screw it in.
Step 3: Add Heater
Drill a hole in the corner big enough for the heater pad cable to fit through. Mount the thermastat next to the fan by drilling two holes and screwing it in. mount the tempature probe on the screws of the fan towards the top of the box. Leave the heater pad out for now.
Step 4: Make the Light
Follow the shamtic and arange it how you want it. I put the four red in a square and the blue in the middle. Sorry for the bad Drawing
Step 5: Instal the Light
Use 4 self tapping screrws with spacers to mount the board to the wall of the contaner and feed the wire for the positive and the negative wire through the whole you drilled earlier.
Step 6: Add the Timer
connect the positive and negative wires from the fan and the light to the termanels on the back and screw the timer on to the box. Mine kinda off hangs of a little bit but it stays on nicely.
Step 7: Add the Heater Pad
Feed the chord through the hole and lay the heater pad neatly on the bottom of the box. Mine overhung so i just folded over itself and it fit rather nicely. Then plug the chord into the thermastat and your ready to go.
Step 8: Finished!
Now all you need to do is plug it in set the timer add the plant and wait. I have my timer set to have the light on 14 hours a day and the thermastat is set to 75 degress. I also took a water bottle glued a hose to the lid and hung it from a stand to keep a constant supply of water on my plant.