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Author: Subject: microwave modifications
CherrieBaby
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[*] posted on 20-1-2006 at 10:20


Quote:
Originally posted by chromium
I too have told that microwaves are very dangerous so do it outside and use remote switch. You probably can drill hole somewhere. Tube with 14/23 joints in both ends that goes through hole should let you connect liebig condenser with small flask that is located inside microvawe. You can use bent tube so that some shielding can be put over the hole.

[Edited on 7-12-2005 by chromium]
You need to do more than just drill a hole through the top for this. You need to affix a metalic cylinder of a certain length to the hole and put a pyrex tube through that to connect to the flask in the microwave. The refux apparatus can be put on top of that tube. The cylinder must have a certain maximum diameter and minimum length to prevent microwaves escaping.

I will try to get hold of the references I have for this and post them. However there a several books on microwave chemistry and the subject of suitable oven modifications is covered in general in some of these books and in detail in various journal articles.

So - it can be done - but you MUST know what you're doing and should, ideally, get a suitable meter to measure any possible stray radiation after you've made your over mod.

[Edited on 20-1-2006 by CherrieBaby]
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bullstrode
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[*] posted on 20-1-2006 at 12:44


"You need to do more than just drill a hole through the top for this. You need to affix a metalic cylinder of a certain length to the hole and put a pyrex tube through that to connect to the flask in the microwave. The refux apparatus can be put on top of that tube. The cylinder must have a certain maximum diameter and minimum length to prevent microwaves escaping."

Cherriebaby, be a good boy and read the thread.

Whether or not you can just drill a hole depends on the size of the hole and how close you are. Last time I checked (it may be lower now) the limit for microwave exposure was 10 mW/cm2, mainly to protect the lens of the eye, which has low perfusion and heats up easily. Something like a 10 mm hole wouldn't be dangerous provided you keep your head a good distance away - say 1 m. As to testing the setup - you need a calibrated meter, which is expensive: the crappy meters you get from fear and greed stores will be useless. Just follow the rules of thumb and you will be fine.
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CherrieBaby
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[*] posted on 29-1-2006 at 03:09


Journal of Organometallic Chemistry, 384 (1990) C57-C60
Design and application of a reflux modification for the synthesis of organometallic compounds using microwave dielectric loss heating effects
David R. Baghurst and D. Michael P. Mingos
Abstract
A commercially available microwave oven has been modified so that syntheses involving the refluxing of organic solvents can be safely and conveniently undertaken. The applications of this technique for accelerating the rates of reactions leading to the synthesis of some commonly used organometallic and coordination compounds are described.

Attachment: mw.reflux.modification_J.Organomet.Chem.384.C57-C60(1990).djvu (60kB)
This file has been downloaded 709 times

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DrP
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[*] posted on 30-1-2006 at 02:34


After watching a program on sky called 'Brainiac' I would feel uneasy about putting solvents in the microwave... :D Each week they'd blow up a another microwave by putting a beaker of solvents in it or a balloon of hydrogen along with a small strip of metal to produce a spark. Some of the explosions were quite impressive, espessially the hydrogen.

Their motto was 'don't try this at home - we do it for you so you don't have too' Program was quite cool - they tested old wives tales and myths in a (semi) scientific manner and blew lots of things up. kind of a cross between Science Shack and FHM magazine.
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12AX7
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[*] posted on 30-1-2006 at 07:24


Ah yes, Brainiac. Saw one a few days ago about "exploding paste", "which is made with iodine crystals and another secret ingredient" (obviously they aren't allowed to say ammonia on the TV anymore :P ). I suspect they set up the pranks differently from the paintbrush and can though...

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Marvin
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[*] posted on 30-1-2006 at 12:39


(more than tad off topic).

They make a lot of mistakes in theory too. According to them PETN det cord goes at "seventeen and a half kilometers a second". I think they probably mean 17500 fps...

Also one of the 'explosives' was according to them, pure oxygen. 'The pure oxygen combusts and expands rapidly, obliterating the microwave' (or words to that effect).

They test single explosives by name. Blackpowder, TNT, det cord. But they jazz everything up and planting the cliche'd to hell and back petrol filled cans, flash pots and smoke devices all over the shot. They've even been known to do petrol/gas explosions and colour the flames in post production to resemble the chemicals they claim to be explosing. (Lithium compounds, copper etc).

They've tested rubidium with water, and cesium with water, but so much of what they do is faked, or simulated, you can't really be sure.

One of the dumbest thing they did was 'ultrasonics', they'd blow an ultrasonic whistle and ask people to phone in if a pet responded to it. Now there is me thinking this is an obvious hoax and they have to admit that the broadcast system (MPEG1 layer 2 audio) simply isn't capable of relaying the ultrasonic tone even if our TVs were capable of emitting it( which they arn't) but..... no. They were serious. Some very good ideas, some style, a lot of very bad ideas and a lot of broken caravans.
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DrP
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[*] posted on 31-1-2006 at 01:50


Your right - the 'brown noise' experiment was a joke and they never do enough controlls or try to reproduce anything but it is a good laugh (thats all it's supposed to be I think).

Has anyone seen 'Look Around You' You should check that one out.
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CouchHatter
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[*] posted on 2-8-2020 at 16:03



Quote:

As to testing the setup - you need a calibrated meter, which is expensive: the crappy meters you get from fear and greed stores will be useless. Just follow the rules of thumb and you will be fine.


There are plenty of videos of people pointing these cheap $30 meters at their microwaves, then covering the microwave with foil, and showing almost a complete reduction in the detected energy.

Someone in a review of the cheap meter, "what have here is a basic device to measure 1 axis of eletro magnetic field. professional device will measure 3 axis but will cost much more." Is this why it would be useless for ascertaining safe levels of radiation?
Or is it because the potential leaking amount with a modified microwave is much greater than a couple hundred μW measured with one of those cheap meters?
Or, because those cheap devices only indirectly measure RF radiation?
Or some fourth thing?
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