Gallery, Projects and General > How to's
Electrical Demagnetizer
madjackghengis:
--- Quote from: Bernd on March 25, 2010, 12:15:28 PM ---Hey nice Roy.
Ah Mad Jack I've got to give one of these :wack:
Go back and look at my OP. Notice that I use the coil with the finer wire, not the whole transformer. I remove the secondary coil and use it be itself. I was just showing what that transformer looks like when removed from the micro wave oven.
Remember the magnets in the magnetron are also good items to save.
Bernd
--- End quote ---
Ah Bernd, I was speaking of "flyback", which can and does occur in a single coil, in the right (or wrong) circumstances. With that great big coil of fine wire, opening contact suddenly can give an induced high voltage pulse just as an ignition coil does, even without a second coil just from the collapsing magnetic field. The addition of field pieces with a gap between them also improves the efficiency of the magnet as well. If I remember right, the fan motor I used in the picture, came out of a microwave oven. I save that high voltage transformer for the day I have to power the magnetron with it, to interfere with official radio communications and stave off the invasion of the aliens. Mad Jack
madjackghengis:
--- Quote from: Bernd on March 31, 2010, 08:53:07 AM ---Hey Mad Jack. Sounds like my kind of thinking on the transformer. That would be an interesting project. :dremel:
Bernd
--- End quote ---
Bernd, there is a capacitor of high voltage across the magnetron, which is half a tuned tank circuit, with the transformer and the inductive load of the magnetron being the other half of the tank circuit. Connecting it all up as it was in the original, with a spark gap installed in this high voltage circuit with the gap adjustable with a wooden handle of some sort, and getting it adjusted to where it crackles rather continuously, gives a high output of RF, and very odd and changing high frequencies, that is RF wise, about as noisy as it can get. You do need a disc reflector of some sort on the "nozzle" output of the magnetron, to provide a "ground plane", which closes the high frequency circuit allowing the nice crackling effect. The out put of the transformer can be run through the primary of a good high voltage car coil, and its output run into a nice dome or the like, again with an adjustable spark gap, to generate the oscillation, and you have a medium sized Tesla coil which ought to approach half a million volts or so. Running the output of the transformer into a conventional shallow cone primary coil, with a 100 to one "tower coil" as is standard for Tesla coils will get a really good effect, and probably close on to a million volts, again with an adjustable gap. That's just for people who really enjoy playing with high voltage and aren't afraid to die. Working around radar too long can give a person a bad attitude toward high voltage, and a lack of proper respect. Mad Jack
Bernd:
Yup, understand about the fly coil. But you got me beat on all the other info.
Guess I won't try for the high voltage, bad heart ya know. :lol:
Thanks for explaining though. Didn't know you have such an extensive background in "electricity".
Bernd
madjackghengis:
--- Quote from: Bernd on March 21, 2010, 12:44:49 PM ---
--- Quote from: websterz on March 20, 2010, 07:46:32 PM ---I regularly make small batches (50 or so) parts out of 4140. After hardening and surface grinding them there is always some residual magnetism in them. I bought a 4x6 surface demag'er from Enco planning to spread the parts out on a thin piece of card stock and treating a whole batch at a time. Plus it will be big enough to do drills, hand tools, etc. Just under $40 with free shipping. Cheaper than scrapping my microwave I guess... :dremel:
--- End quote ---
Being close to a transfer station (junk drop off) I've picked up the dead micro-waves. I've got at least a dozen or so transformers.
The reason I started collecting these was/is I found an article on the net about making your own spot welder using two rewound transformers. I've got the article stored some were on my disk drives.
I'm sure you could find them laying out on the curbside on pickup day.
Bernd
--- End quote ---
Hi Bernd, I have to say it felt good to catch you off guard with the fifty one hole index plate! I was wondering if you ever did anything with the idea of the spot welder, or have any other experience with a spot welder. I've got a top of the line ESAB welding power supply I use mostly for tig but occasionally for stick and have been considered using it, as it is all solid state, with a solid state contactor setup. I haven't tried it yet because I seldom need to spot weld, and usually plug weld instead, so far, however if I had a good, solid set up, I would spot weld pretty often if it were convenient. By the way, I assume your avatar is a scale model, do you have a build log or some more pictures showing more of the truck? mad jack, out in the noonday sun, again!
Bernd:
Mad Jack,
I used to to do quality control on first parts coming off cnc machines. One job was checking holes on a bolt circle. So I had to figure out the X & Y settings for the coordinate checking machine. That''s when the light came on when you said "coordinate" and the drilling the holes. Ya! I can do that.
I haven't done a thing on building the spot welder. Really no need for it. But if you interested I'll see if I can find it.
The sotry behind the avatar. That picture came out of the August 1975 Hot Rod magazine. Back then I was quite interested in cars. That truck is a total scratchbuilt vehicle. I just like the design on the old Mack trucks. Here's a pic with the full story. The guy has a web site. Google "low buck tool" and read about the way he got started.
Bernd
Navigation
[0] Message Index
[*] Previous page
Go to full version