Sciencemadness Discussion Board

Microwave related

Organikum - 14-6-2003 at 07:50

The best source of information on
microwaves/waveguides/magnetrons/antenna....
I ever found on the net. Makes the bridge between practice and theory and bears lots of inspiration. Easy understandable principles of waveguide-design (how to come around this corner... ;)), rotable connections etc.

Was perfect for me - maybe it helps someone else also. :D

Haggis - 15-6-2003 at 18:43

Eh, Organikum, interested in the ol' HERF rays? I've dabbled with them once. Built myself a directional horn for it and etc. It ended up working once, then fried due to some internal circutry error. It was nifty too, all the working fit inside of a computer power supply case with the magnetron and the horn on top. Had a 'remote' control on a 25 foot cord so I could hide behind a cement wall. Nifty stuff to dabble with. There's a great file on the FTP dealing with the effects of 2.45 ghz radiation on commercial explosives. If you are into microwaves as you are into the other subject mentioned, you should like it.

Organikum - 15-6-2003 at 22:33

I played with directed microwaves some time ago - will dl the file you named as soon the ftp is available again. I was mainly interested in the possibility to grill all electronics on distance. Came so far to proove accidently that the shieldong of automobile electronic isn´t very good. Was a quite expensive proof so.... :o
Precooling the magnetron with CO2 (dryice) and pulsing slightly (ehem...) higher voltage in addition to a horn antenna gives astonishing performance. Better would be to use a lens for to get low power density at the source and concentration at the point aimed for - safer and more effective.

Meanwhile I play with the use of the micro for chemistry - highly interesting also! :D

Haggis - 16-6-2003 at 09:26

That is indeed the file, however I didn't open it, I just recognized the name. There is a (IIRC) bell curve of sorts in the voltages a 2.45 ghz magnetron will preform in. My transformer for the magnetron kicked out 1.6 kilovolts and 400 watts- a relatively low powered device. Orgy- Unless you are running your magnetron for extended periods, you shouldn't need and external cooling. If I did need to cool it, I would just mount a heatsink onto the mounting area, for this would be easier that supplying it with dry ice, but whatever floats your boat (or cools your deathray). Yes, they sure do knock out electronical devices, pity about your car though. My test dummy was a watch. There is some research in the military with directed waveforms, however they used millimeter wave forms, the long waves of microwave 2.45 would affect internal organs too adversely. The millimeter wave heats up the first few layers of skin rapidly, causing pain, but no after effects. Popular Science/Mechanics (not sure which one) has an artical on this, which may be intested, Uncle Sam used one of their reporters as a test subject, quite interesting.

Organikum - 16-6-2003 at 12:16

It wasn´t my car :D

The magnetron was pulsed aka powered by a capicitor bank, I will look for my old papers how much output there was - it is some time ago. After the incident with the car and some capactors exploding short after I left this field of experimentation. (says not I won´t return someday).
I read about the experiments of the army on "not so lethal weapons" and I have a strong disbelieve in anything related to. As I know that humans in a state of exaggeration, highly emotionalized and driven by an collective emphasis are actually not to stop by anything whats not lethal for at least some of them.
(same effects are visible when people are under the influence of cocain or amphetamines in a conflict).
I guess there is the old military logic driving this project, the logic that a wounded enemy is better as a dead one. So fascinating the techniques are - the logic behind is mostly perverted and obscene. (my opinion - understood)

thanks for the file
ORG

some interesting patents

Organikum - 19-6-2003 at 03:39

Attached are two patents describing apparati for microwave irridation in chemistry. The one is a "all in one" multifeature device - somewhat overdone in my eyes, but the other one is obviously based on a household microwave and even more than only inspiration - this can be adapted! With plans!

Now a not really related pic for the multimedia touch :)



WinRAR3.0 or higher and DJVU plugin/viewer are needed.

[Edited on 19-6-2003 by Organikum]

Attachment: patente.rar (395kB)
This file has been downloaded 933 times

microwave raygun project

Organikum - 8-7-2003 at 21:11

These pics are from a project where the guys who buildt it cancelled the whole thing as it got too impressive - thats what they told before taking the page from the net.
Internetarchive proudly presents:

the pics




This is obviously "dramatized" to make it more impressive




I don´t believe that this thing worked in any way: A glass or plastictube is no waveguide, it even doesn´t reflect microwaves so the waves are not directed but dissipated in 180° degrees from the magnetrons outlet.

But looks good !

more serious

Organikum - 8-7-2003 at 21:31

Is the attached circuit layout for fullwave voltage doubling power supply of a magnetron with filament heating separated.

Thats what is needed for experimenting whereby the volage doubling isn´t necessary for organic chemistry related experiments (the very most at least). This is also basic for a better power regulation. (0,2 to 5 Hz pulsed)

Attachment: fullwaveVdoublerMW.tif (14kB)
This file has been downloaded 1413 times

waveguide tuning

Organikum - 19-7-2003 at 19:44

A waveguide can be tuned by simple means to "synchronize" the microwaves so there is a common wavefront - standing waves.
here is the schematic:



I believe the terms are understandable also they are in german


Main parts are:- magnetron + zirkulator (thats just a piece of waveguide)
- impedance analyser + 3-screw tuner (thats really only 3 thick screws reaching into the waveguide)
- resonator (a resonating box, says the dimensions are n x 1/2 wavelength, standard MW ovens deliver 12cm waves)

a_bab - 24-7-2003 at 02:58

Quite an interesting aplication of the microwave owens is the metals melting . Yes, it's possible to heat metals up to 1000 degrees C. Here is a page dealing with this.

Organikum - 25-7-2003 at 00:27

Thats very interesting! Good read the link, thanks a_bab!

The author has some severe misunderstandings which lead him to wrong conclusions so.
- The hot spots he speaks of in test crucibles made are caused by "hot spots" of microwave irridation, the build up of standing waves caused by the removal of the rotating table which is made to for exactly this: to hinder that food is partially burned to ash by those energy concentrations. The overall chaotic energy distribution is the problem in melting metal for the energy is never to focus on a spot. Also in the basically much to small caverns of household microwaves chaotic standing waves occur whats another problem.

The above described device bundles the energy to one point which is to regulate in intensity and location in the resonator by the three screws.

As told, temperatures over 2000°C are not unrealistic. Thats hot!

PHILOU Zrealone - 13-10-2003 at 04:01

Once I have made a cake by microwave and believe it or not despite it wasn't wel cooked outside it was carbonised inside and hard as a stone.

Microwave for chemistry....In the depertement next to the one I have made my end study work, they were studying the effect of microwave and sonowave on chemical reactions.
Despite many attemps microwave was proved to be as good as simple heating.
On the contrary sonication had some weird effects and sonication was studied vs ultraturaxing.Ultraturaxing produces also cavitation bubbles.

Weird results:
Ultraturax is better than sonication especially when you have 60000rpm variable ultraturax...less expensive than common Nickel horn which decompose/corrodes quite fast.
*Gringnard reaction could be done without complexating ether!
*at a certain point (over 11000 rpm) a endothermic minor product start to be favourised over the natural one in a substitution reaction.From 0% to 80%.

So Organikum,
What reactions do you want to study with microwaves? ;)

Oscillating Magnetic field in the melting of metal is wel known (fast sinusoidal variation of current for tiny amounts of metal to melt) and slow variation for big amounts).
Electric oven are in use in industry.

If one is able to concentrate/foccusate or make a resonnance out of any kind of ray it can lead to strong destruction/effects.

Ph Z

Iv4 - 19-10-2003 at 00:33

Nice page!

Mircowaves are prety usefull if your going to work with carbon dioxide and copper vapor lasers(but thats just IMHO)and probably prety usefull for studying magnetic cooling.

[Edited on 19-10-2003 by Iv4]

thanks Philou!

Organikum - 23-11-2003 at 09:32

the ultraturaxation was complete new to me - I even had never ever heard the word before .....
Whats means nothing.

Yes, the old question on the microwave effect - existing, not existing?
Anyways, some reactions profit alone from the homogenous heating very much and microwaves are a wonderful gadget to play with - and scrapyarditems also.

Dangerous of course, the non-intuitivity is a factor not to underestimate, I say only "slit-antenna"......

But what here discussed is not dangerous at all?
What is not dangerous and makes any fun?

I can PM you my new address as soon as I have one so you may send me this nice ultracentrifuge-gadget - I love to try it... LOL

And regarding the cooking of cakes in a microwave - RTFM first?

[Edited on 23-11-2003 by Organikum]

slvr_phoenix - 2-12-2003 at 12:27

Quote:
Originally posted by Organikum
I was mainly interested in the possibility to grill all electronics on distance. Came so far to proove accidently that the shieldong of automobile electronic isn´t very good. Was a quite expensive proof so.... :o
Hmm... I might have to consider such for the day that I finally flip out and decide to punish all bad drivers.

It would be an even better and less conspicuous vehicle-mounted automobile disabler than an uncercarriage-mounted turreted nailgun to take out one of their tires. (My idea of using a nailgun had been on the basis of having run over a nail being a plausible coincidence and it being much easier to maintain than a dry ice dart gun.)

... Not that I've flipped out yet and actually mounted anything like this on my car. I'm just planning ahead for the day that I do. :o

Organikum - 4-12-2003 at 15:32

You might look for Xoo1246´s "explosive driven powersupplies" and their possibility to generate a VERY strong EMP.

Kills the radio and cellulars also - what might be an advantage.