Freezer inside another freezer

>>1171942
Try it out and report your findings. Obvious i would worry anout how to power the mini fridge and how much heat it will produce inside the freezer.

If this doesn't work out just buy one of the freezers scientist use when holding samples

>>1171958
>how much heat it will produce inside the freezer

i think that's the main problem OP will encounter.

This nigga's trying to put a fridge inside a fridge

>>1171942
I applaud your dedication to astronaut ice cream
I personally think it taste like ass

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>>1171942

>>1171994
What does ass taste like? I've never tasted either.

Freezing freezers results in some kind of exponential heat load I think. Look at cryogenics.

>>1172018
You're missing out.

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>>1171942
a freeze dryer is basically -

a refrigeration unit where the evaporator coil is in a insulated sealable container, where you put the sample in your container, seal it, then use a vacuum pump over a few hours to remove the air & moisture. the refrigerant is r404a.

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>>1171942
>Put a vacuum canister inside the mini-fridge
Since the vacuum won't transfer heat you'll have to wait a looooong time for what's inside the canister to freeze/sublimate.
The moisture sublimated into the vacuum needs to be removed.
If I leave ice cubes in my 'normal' freezer too long they sublimate without a vacuum.

Improve the sealing on a freezer
Attach a vacuum pump to freezer
Turn freezer thermostat to lowest setting
Place items in freezer
Once food is frozen, turn on vacuum pump
Turn freezer thermostat up to 'normal' setting
Wait...

>Once the food is frozen, the freeze dryer creates a powerful vacuum around the food. Then, as the food is slightly warmed, the ice transitions into vapor and evaporates.

How long does it take to freeze dry something? A lot of vacuum chambers can hold a vacuum for few hours and can be detached from the vacuum pump.

>>1172112
And it really doesn't take long to pump out the air, so theoretically you could find out the rate at which the vacuum chamber normalizes and pump out the air as needed, keeping it frozen between pumpings.

>>1171985
>yo dawg, I heard you liked to fridge

>>1171942
whichever freezer you are going to put under a vacuum, reinforce the shit out of it, look into the psi for whatever bar you are trying to achieve. Shit will implode on you

>>1171942
> hurr durr i'm a retard that doesn't know what an auto cascading refrigerant is.
two stage, auto cascading refrigerant system. 508B is popular. better yet hang yourself because you are a waste of space and can't afford to do anything right, you worthless sack of shit.

>>1172106
OP here. Holy shit, thanks anon, that sounds a lot simpler than my plan.

I have a freezer my friend was going to throw away that I'm messing with right now. I have a plate of fruit and a plate of salt on a shelf beneath it to absorb any water from the air. Just alternating between min and max freeze seems to be working, albeit slowly.

I'm not going to pressurize the freezer, since it probably will implode. Instead what I think I'm going to do is find an old pressure cooker and mount an air nozzle and a pressure gauge to it, then fab this thing to occasionally pump the air out of it as needed:
https://www.youtube.com/watch?v=vaho7JSVS1I

There's a store nearby that sells vacuum pumps and all the electronics parts to make this shit automated, but I'm going to wait until I've got a basic working system before I drop real money on this project.

>>1172941
Thank you for the information anon. I don't know too much about this sort of thing yet, and every time I look stuff up, my search is so fogged with consumer shit and home improvement shit that I can't find any specialist stuff. I guess not too many people like to diy cryo stuff.

>>1173382
>I'm not going to pressurize the freezer, since it probably will implode

Freezers are pretty sturdy. I doubt you'd get it sealed well enough for a full vacuum. (-14.7psi)
If you could find a junk appliance with a working compressor (refrigerator or freezer) you can use the compressor as a vacuum pump.
If the freezer you are using for your 'freeze dryer' has a drain, that you be the place to connect your vacuum pump.

I think you'd be working yourself to death with the PVC pump trying to move 10 - 15 cubic feet of air and hold the vacuum low enough and long enough to do any good.
(still fun to make one just to have it)

>>1173392
>that you be the place
*that would be the place...

>>1173393
Just sabotage the thermostat in your free freezer so it keeps cooling. -30 would probably be doable. As mentioned the compressor from another freezer makes a suitable vacuum pump

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OP here. Jury rigged this thing out of a fish tank bubbler. Couldn't get a good vacuum at all, turns out hot glue is a terrible sealant. Still tried it because it does give a bit of a vacuum. Left it in the fridge with an ice cream and it got foggy inside the container after 30 mins, so I guess it was sort of working? Also started making noises though, so I stopped it and ate the ice cream. It had developed a sort of skin already, so something was happening.

Whatever the case, I went to my favorite local used shop, and they gave me a fridge compressor for free. Next paycheck in a week or so I'll get a bunch of air fittings (they are kinda expensive in my country) and build a proper ball valved pvc vacuum chamber.

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I went to the shop again because I wanted to see how the compressor attached electrically to the freezer, and then to the wall. I figured there would just be a transformer with a couple more plugs for fridge lights etc, just pop out and use the original cord. Nope it's a new, very big, and very nice fridge. Actually very complicated, big circuit board with lots of parts including a heat sinked processor!

I admittedly don't know much about electronics, I was intending to learn using this project. I do know enough to be terrified of those 3cm wide capacitors.

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You don't actually need to get all that cold, but to freeze dry properly you need to effectively control several temperatures along with the vacuum.

If you just pull a vacuum in a cold chamber you will dry the product, but you will also be pulling all the water vapor through the pump which will destroy it very quickly. You are supposed to hold a precise level of vacuum and then warm the food while cooling the chamber so that the water in the food sublimates and then deposits on the chamber walls.

>>1175974
For my first build i'm going to just fill the bottom of my pressure vessel with calcium cloride dessicant. Another freeze dryer builder did that with good results. Other people run the compressor line through a dry ice bath, but I don't want to have to buy draw ice every time I do this. The extreme cold I want is mostly so the water condenses on the cooling element before it gets sucked up. For my final build, I've abandoned the double fridge idea and am thinking about building an independent system. Pic related.

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>>1176093
Forgot pic. I will be running propane, which will allow me to get to -42c, it's boiling point. This is important because icecream has weird properties that requires it to be frozen below -30 for proper freeze drying. I may also want to use this as the first part of a compound freezer, maybe with the future goal of making dry ice.

>>1176097
>File: 2017-05-12 13.14.10.jpg
I had no idea you were an aussie, mate.

>>1176097
It's really uncomfortable to stand on my head but I'll try!

It's about the stripped exif-data..

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>>1172018

Like this

>>1176403
Why you think so, because of the time zone or because it's upside-down?

I'm actually in Japan.

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I've built my pressure vessel and I've got my vacuum pump 90% ready. All that should be left is soldering the power cable on.

The problem here is I'm stupid and don't know what's positive, what's negative, and what the third wire does. In the original fridge, three wires go into the board, there's a bunch of stuff in between, then two wires come out and go into the wall. The motor is the same voltage and hertz as the wall, 100v 50-60hz, so I don't think I need any sort of transformer.

While I do want to learn about electronics, cluelessly messing around with mains power sounds like a dumb first project to me, so if one of you guys can tell me how to solder a plug onto this thing, I'd really appreciate it. I've got the schematics, upload in the next pic.

Background info, in Japan, the outlets are two prong, and either direction works. Sometimes appliances have a grounding cable that you literally screw in, inside the outlet faceplate, but the original fridge didn't.

The little round thing on the side is an overload protector, don't need to worry about it for now.

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>>1176691
Here's the schematic. The moonrunes on the wires are their colors, and I put little dots of the appropriate color on them where I think they matter.

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>>1176695
Other half of the schematic

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>>1176691
>>1176695
>>1176697

>>1176691
>>1176695
>>1176697
you just need a potential relay. the connections to the compressor are common, start and run. you send power to start for only a few seconds to get the motor up to speed then you kill power to start and send it to run. thats what the potential relay does. google that shit

I like this thread, hope OP gets his ice cream. Bump

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>>1176723
>>1176727
Thank you! I don't have an ohm-meter, but looking at the wiring, I think the top is common, and the bottom two are start and run. Other 3 prong connectors by the same company (fusite) all seem to have the same layouts as well. I decided to try pulling off the ptc relay and common connector from an intact fridge and just put it in the same orientation on my standalone compressor. Then I'll plug in that fridge, which should power my compressor.

I'm worried that
#1 I did the connections wrong and
#2 The potential relay etc. is too small, since the compressor attached to the fridge is smaller that the standalone one.

Am I being stupid? If I plug it in right now, what's the worst that can happen?

>>1176830
I appreciate it, thanks

>>1171942

>>1177616
>File: IMG_20170515_172937.jpg

That black box with the blue wire is the PTC device.
Inside it is a semiconductor disk that changes resistance with temp/voltage/current.
The disk it clamped between two metal plates with female contacts on them.
The blue wire is going to the RUN pin on the compressor.
The other female connector is going to the START pin on the compressor.
The heavier gray wire is connected to the COMMON pin.
The gray wire should connect through the OVERLOAD to the 'hot' power connection.
The blue wire is to neutral.
When power is applied current flows through the overload, through the run and start windings to the neutral
Part of the current will be flowing through the PTC disk which has low resistance when cold making the momentary connection between START and RUN pins.
The current flowing through the disk causes it to heat up almost instantly raising the resistance effectively disconnecting the START pin from the RUN pin and neutral wire.

If your compressor pins have the same layout with one pin on top and two below it should work fine.

The PTC device may 'wear out' sooner on the larger compressor.

>>1177651
>through the overload, through the run and start windings to the neutral
through the overload to the common then through the windings to the start and run pins to the neutral

>>1171942
OP IS a moron (or just Southern).

Op trying to Heisenberg

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>>1177651
I noticed my spare fridge also had an overload protector, so plugged it in with the other compressor wired to it, and it worked, very well! Crazy well! Left it for a bit and the vacuum held, chamber works well.

But then when I tried again after a few runs, the compressor would shudder, but not start. If I turned it off and on again immediately, nothing. The longer I left it off between tries, the longer it would try to start, up to about a second before it stopped doing anything. I figured some sort of automatic control in the fridge might be messing with it, so I took it out and soldered it up as you instructed, pic related.

I then hooked it up and gave it a shot, same problem. Figured I might have fried the PTC so I moved the connectors over to the compressor on the spare fridge, starts right up, works fine.

What do you think is going on?

>>1178146
>But then when I tried again after a few runs, the compressor would shudder, but not start. If I turned it off and on again immediately, nothing. The longer I left it off between tries, the longer it would try to start, up to about a second before it stopped doing anything.

This it the overload protector (a breaker) shutting it off.

The compressor that doesn't start may need a start or run capacitor and you just got lucky on the first try.
Also could be pressure not equalizing between the vacuum and pressure lines after the compressor shut off.
If there is still high pressure on the output of the compressor when it tries to restart it will not be able to start.
This is why air conditioners and refrigerators need three to five minutes after stopping before attempting to restart.

how inefficient are older freezers the size of OP's?

ive got one about 20 years old that's starting to rust through a bit on the top.

still runs, but it's just how $ electricity is now.

Lol the fridge has coils and fans that get rid of heat from the area you are cooling. So no a freezer in a freezer would not work