Friday, May 10, 2013

Defrosting My Food (Part Three)

Okay, so I realized that using an old power supply unit was a good idea (see Part Two). However, it is also loud because the fan echoes around pretty badly inside this empty metal box.

The second problem I discovered was that not all plastic storage containers are created equal. I tried to defrost some frozen spaghetti on top of this unit, but the bottom of the plastic container does not have a flat surface where the frozen part will not make full contact with the top of this box. The solution was to put another aluminum heat-sink between the inner bottom surface of the container and rest the other half on the top of the PS warmer.

This seemed like too much fuss and making the defroster device was just too dangerous if I was forced to make more (for family or friends). My odds might be really good that I would eventually get hurt gutting the dangerous components out of the inside of the power supply. This also leaves a lot of waste still.

So, I decided to make the whole unit smaller by eliminating the PS box completely.

Why not just use the heat-sink and fan by itself ? Small enough to still fit under a plastic container, even with an indented bottom. And much quieter.

The unit in the photo above was made by a friend of mine from a concept drawing I gave him. We hadn't quite worked all the bugs out of the idea yet but this was much less complicated. He rigged his to work on a 9 volt battery and power switch. We found this design much quieter, more portable and more efficient overall.

Knowing that the look of the above prototype wouldn't win points with my wife (I don't want that thing in my kitchen!), I knew it needed to be refined again. Plus, the battery would probably not last long enough to actually do the job required.

So, one more design refinement and we had a nice looking unit that runs on a power supply through AC.
So, does it work? You bet.

I put two regular ice cubes in a small plastic container and set it on top of the new unit. The ice cubes completely melted in 1 hour and 40 minutes. Then, I took that same container and placed two identical ice cubes in it and set it on my desk. It took 3 hours and 20 minutes to do the same thing. And in case anyone is wondering, the room was at 23 degrees Celsius throughout the experiment.

I think it looks like a NASA Lunar Lander.

Defrosting My Food (Part Two)

So here is the second half of my project to defrost my lunch (or whatever else) utilizing old computer parts.

Warning: Be certain that if you are planning on replicating this project for your own use (which is fine with me), take extra special care when removing the circuit guts from the inside of the power supply unit. There are large capacitors and other assorted things that can quite possibly give you an electric shock, the likes of which you have never experienced. This shock can cause serious harm and quite possibly, death if you are not careful as to what you are doing. I will not be held responsible as this is strictly an experiment of my own and I am a certified computer technician who is well aware of the risks.

The first plan of attack I had was to gut an old computer power supply (PS) and use the box as a sort of plate/ air chamber defroster. I left the fan inside of the unit and attached it to the switch which is also already installed in the power supply. On the top plate, I attached an aluminum heat-sink from a processor and even used the 'transfer paste' between the two surfaces.

When this is assembled again, the fan will pull the air in from the ventilation side of the PS box, pull it across the heat-sink and out of the front of the unit. When you put something frozen on top of the (PS) box, the cold is transferred to the box itself and absorbed by the heat-sink. Pulling room temperature air across the heat-sink will help to warm it up.

I tested this device and found that it worked pretty well as expected.

Thursday, May 9, 2013

Using Computer Parts and Science to Defrost My Lunch (Part One)

I have been a little absent lately. My only excuse is that life and priorities got in the way lately.

One thing will never change though. My need to create and re-purpose. And on that note, today's post is not so much about the re-use of furniture, but instead, old electronics or at least some parts of old electronics. Here was my dilemma:

I tend to be a person who forgets to plan ahead.  Possibly through procrastination or just out of already having too much on my mind or plate to realize that I missed something. In this case, I tend to forget most often to make a lunch at night before I go to bed. Or, I just get lazy and pass the chore off to the next morning. This is a bad idea of course on the best of days because I already know 'full-well' that I am a terrible morning person. Deep down inside, I know that I am just setting myself up for failure.

So what does one do if he is running late and doesn't plan ahead for lunch? He grabs a frozen leftover out of the freezer, throws it in his lunch-bag and runs to work. So, the new problem is that this leftover will probably not defrost before the lunch hour. Then I will waste most of my lunch hour trying to defrost the frozen center of my lunch in the microwave. Of course, all this causes is uneven food and heat distribution and you are forced to eat that frozen 'chunk' in the middle or toss it away completely. It also means that your coworkers will grow impatient because they need to 'nuke' their lunch as well (and may also have a frozen brick to contend with).

The trick I started using was that I would take out my frozen 'lump' and set it on top of my metal filing cabinet. The aluminum material in the cabinet acts as a natural hot/ cold absorber (ask any science teacher about natural temperature transfer and metals). This would help speed up the process, but would rely on the room's temperature and the natural distribution between cold and heat. This wasn't good enough for me, so I took it one step further.

I work in the IT department at my company and quite often have old or spare parts piling up in a corner of my office. If you have ever looked inside a computer, there is always one spot that holds a fan and a large aluminum 'fin-like' heatsink block directly under it. This serves to draw the heat away from your processor by transferring it to the aluminum and into the open air. The fan serves to help pull away the heat and replace it with cooler room-temperature, in effect, cooling down the processor beneath.

I also wondered how well this would work for frozen things?

Stay tuned because I have a few ideas I want to try out!