This project took me about 2 days to accomplish. It costs around $25 and it does a perfect job at dehydrating fruits and vegetables.
Dehydrating fruits and vegetables can be quick, such as 6 hours for certain fruits and about 2 to 3 days for others such as raisins. You need to maintain a constant temperature of 57 degrees Celsius and allow for good ventilation to remove humidity.
a 50cmX40X30cm box
thermostat (purchased from AliExpress) works well
220VAC Fan or 110VAC depending where you live
SPDT relay (to allow the fan to operate when the lamps are out)
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Step 1: Making the Box
The box is made up of plywood or similar with the following dimensions:
50 cm height
40 cm width
30 cm length
(50cmX40cm) for the front door and 50cmX40cm back side
50cmX30cm for the sides (2 each)
30cmX40cm for the top and bottom (2 each)
thickness of the wood should be 1.5 to 2cm minimum
Drill a round hole of 10 cm diameter on the top to accommodate the extractor fan
Drill a 7cmX3cm hole to accommodate the thermostat
Step 2: Insulating the Box
the best way to insulate the box is using metallic tape. (called hi-speed tape)
insulate all sides, this will keep the heat inside a reduce heat loss
Step 3: Wiring
i got this thermostat from the internet it's cheap and works extremely well at regulating the temperature;
remember that you need 57 degrees Celsius for most vegetable/fruits dehydrating process
I achieved this temperature by installing 2 light bulbs on the bottom (one 100W and one 75W) connected in parallel
I also added a relay SPDT in series with a lamp so that the Fan will run when the bulbs turn off when the temperature is reached allowing moisture to escape
Step 4: Adding Racks
Make the racks out of screen to fit inside the dehydrator. I also found an old rack that fit perfectly
Step 5: Final Product
You can almost dry anything, tomatoes, bananas, apples, even onion and garlic, which take less time.