| Myren |
Seems like most of the cost of amplifiers is in power supplies. So i'd like to roll my own superheavy duty transformer and caps....
Caps would be a nice big acrylic box, with thin layers of metal and some sort of dielectric. I was thinking maybe just thin cloth, with a dielectric oil. Lowest K value i can get away with/ Not sure what i'd use for the plates, thin is good, but cant be too fragile.
Safety is obviously an issue. Maybe some kind of metal reinforcement cage, and circuitry to detect breakdowns and provide an easier and safer route for discharge....
Now, where can i get a transformer core? I was thinking perhaps torodial.
Myren |
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| CryingDragon |
| Sometimes u can find them on ebay BUT toridal is small what am planning to do is if you can get your hands on an old microwave you can take the giant transformer out of it and see these are made to supply 2000V at 2A! what you can do if u need less is take the high voltage secondary off and wind your own i'm sure you could make say a +- 70 at 10 amps at least. They are very large indeed but if you can get one it's a goldmine to do it yourself when you price heavyduty trandformers new. If you need any info on the rewinding email me and about the caps...I don't know because there are so many diffrent varables that you have to take into account plus most dielectirc oils are nasty to work with (fumes up the wazoo) and plus for the money you would spend on supplies to make your own caps i would bet you could buy some nice surplus ones. |
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| Narcisse91 |
It would be an interesting DIY project, but in terms of space and cost, I don't think making your own caps would really be worth it. You won't get the precision used in positioning the plates and dialectrics in most electrolytics, which means it'll be a lot bigger, and there are a lot of safety issues that you'll have to prepare against (as you mentioned), adding cost.
As for winding toroids, Micrometals makes some nice cores. I have print catalogs here, but I know they have a website too, so you should be able to search for it and find it.
As for rewinding a microwave transformer, why not just buy a toroidal core and wind that? It may cost more, since you have to buy the core, but in the long run, should end up being much better quality. |
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| BrianGT |
It definately is not worth it for making your own transformers. Sure you can buy nice big cores by themselves, but the overall cost won't be much cheaper. The enameled wire will cost you quite a bit if you can find it in anything less then a full spool. The main issue would be the quality. Without the machines, it would be hard to get a nicely would toroid. I have watched the guy at Victoria Magnetics, a company that makes toroids near me, make transformers, and he uses expensive machines which do all of the work. I could not imagine doing it by hand, especially with you wanting to make superheavy duty transformers. It is not easy to wrap 10ga wire evenly around a large core. I will try to take pictures of the machines next time I go down there, as they are quite interesting.
The only possibility that I would think would be feasable would to get a big old surplus isolation transformer and taking off some of the windings until you get it to the desired voltage.
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Brian |
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| Narcisse91 |
| We used to have a department where I work that did nothing but wind toroids, and it IS possible to do heavy duty toroids (big enough to handle many kilowatts, we design RF generators) by hand (or with some hand tools), and with enough patience, the quality is good, but eventually, we decided it would be cheaper to outsource them, and that's when we were buying cores and cables with bulk pricing... |
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| CryingDragon |
| quote: | Originally posted by BrianGT
The only possibility that I would think would be feasable would to get a big old surplus isolation transformer and taking off some of the windings until you get it to the desired voltage.
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Brian |
isn't that gonna be just as hard? *Yawns* Besides you can't simply take some wires off because big transformers are always potted in varnish to hold the windings in place and when you pull the wire off it flys everywhere,Very nasty mess and it also takes the insulation off the solid wire. i've rewound micro transformers and have been in highvoltage (tesla and the like) for a while now and i say when you can either get an old transformer some wire ($30 MAX,look at ebay) and take the time to rewind it and have a $200+ transformer for $30 it seems logical to me. Just thought i'd offer the idea. |
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| Narcisse91 |
| quote: | Originally posted by CryingDragon
you can't simply take some wires off because big transformers are always potted in varnish to hold the windings in place [/color] |
Not always. |
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| CryingDragon |
| quote: | Originally posted by Narcisse91
Not always. |
ok in every transformer i've taken apart. |
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| NerdMike |
| Remember that you will need approx. 450 turns for one square inch of core to get a reasonable flux density at 120 volts. Turns are inversely proportional core XSA, so if you have 3 sq. inches you will need 150 turns. |
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