On Tuesday 10 December 2013 17:28:10 Dave Cole did opine: > On 12/10/2013 3:18 PM, Gene Heskett wrote: > > On Tuesday 10 December 2013 14:55:24 andy pugh did opine: > >> On 21 October 2013 18:21, Les Newell <les.new...@fastmail.co.uk> wrote: > >>> A trick to get around this is to use a 24V transformer to buck the > >>> mains down to 216V. Add the voltage doubler after that and your DC > >>> is spot on. > >> > >> You seem to understand transforners :-) > >> > >> I am wondering what I can do with this one, that I found in a skip. > >> > >> Ideally I would like a 100V isolated supply, just to be a bit less > >> scary when messing about with servo motors. > >> (Rectified UK mains is 300V + ) > > > > Or about 215 volts rms, 50hz I assume? > > > >> This is the label on top: > >> https://drive.google.com/file/d/0BxjJW1-T6n7Cd2FrOWV5R3dRZnFhV2xrV0F3 > >> OHp 3UW05X2NF/edit?usp=sharing > > > > This label can be a bunch ambiguous. But with the top wired in > > parallel, feeding one side to terms 39 and 37, and the other side to > > 36-38, one would assume the secondaries can then be probed to see > > which could be used to obtain the voltage you need. > > > > Basically two warnings apply. Don't "seriously" overvoltage the > > primary else the iron will become saturated magnetically at the peak > > voltage and when that happens the input current rises dramatically > > and heating destruction can occur. I see it has a 1050VA rating, or > > nominally 1 kilowatt in round figures. The iron saturation point > > isn't a generally published spec but can usually take a 15 to 25% > > overvoltage condition in well built transformers. I ran my mill for > > years on an old tranny from a 2" tape machine, feeding the 127 volt > > primary voltage we get here in the US of Hay, to the primary > > terminals labeled for a 90 volt feed, in order to get 29.5 volts for > > the motors out of the 24 volt winding when using a choke input > > filter. No noticeable heating of that 50+yo well potted hunk of > > iron, but that is "pushing the envelope" looking for the smoke vent > > with more modern iron. > > > > This transformer in the pix, can also handle a nominally 440 volt feed > > by shorting 37-38 together, and feeding the line rails to 36 & 39. > > This would divide the secondary voltages by 2. > > > > They could have labeled it better though, and I doubt if an English > > label would remove any of the ambiguity. If that was available as > > surplus, I'd take a couple of them. > > > > Cheers, Gene > > Good point about saturating the iron via overvoltage. That probably > explains why I melted some 14 gauge wire several years ago.. in a "test > connection". > > Andy said he got the transformer out of a "skip" which I believe > translates to "dumpster". > > As in dumpster diving. A sport in which I am well versed. ;-) > > Dave
Quite familiar with the technique. My fav dumpster is about 80 acres worth, 25 miles east of me, belongs to an ex, now retired employee of the stations. If he hasn't got it, its only because his pickup wasn't big enough to haul it when it was free. Since I was his boss for nearly 20 years, even refused to fire him on one occasion because he was a pretty good "maker" for me, I have to force him to take my money, usually for far less than its worth. If I need some clean cherry or mahogany in 2' pieces, I've hauled off a ton or so for zip. He gets it out of the burn piles at a couple furniture makers hidden here and there up unmarked gullies, trying to get it before they stick a pint of k2 and a match in it. I've made a couple maple gunstocks, and some mahogany furniture for me, and the maple was all I "paid" for. He'd bought a huge slab with the idea of making his own guitar, didn't know it needed waxed to slow the drying so it wouldn't split, but stuck it into the hot air exhaust of the transmitter for about a month. Of course it split like crazy. So I gave him a 20, took it home & stood it in the corner for about a decade. Couldn't cut into it for splits, finally cut a good sized piece for a rifle stock, sealed it in a 60" by 8" section of sewer pipe & pulled a hard vaccum on it for about 6 months. Couple hairline cracks I worked some superglue into, and now its thumbhole style with my TC black diamond BP rifle snoozing in it. Gets ooohs and aahhs at the range when I bring it out. That WAS the general idea. That and a couple other details have made a 1.25" grouper at 50 yards out of it, good considering that when I bought it originally, a 6" group at 25 yards was a good day. One of the toy's he has sitting out in the weather is the welded frame of a low band diplexer assembly, about 4 feet deep, 6 feet high and 5 feet wide, 4" heliarc welded alu angle. Looks like it would make one hell of a maker- bot frame. But I'd have to build a building for it and I'm darned near out of real estate I can put more roof over. But I stand and stare at it drooling slightly, every time I go over to see what he has that I can use for one of my current projects. He also has some huge, but probably peanut powered, 2" quad machine reel servos that could handle up to 14" nab tape reels. Designed for torque mode to maintain the tension on the tape +-10% or so at any diameter of tape pack on the reel at very low rpms in play mode, or 2-300 revs in rewind modes and some suitably accurate lead screws (nope), I'd already be nailing shingles. :) > ------------------------------------------------------------------------ > ------ Rapidly troubleshoot problems before they affect your business. > Most IT organizations don't have a clear picture of how application > performance affects their revenue. With AppDynamics, you get 100% > visibility into your Java,.NET, & PHP application. Start your 15-day > FREE TRIAL of AppDynamics Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.cl > ktrk _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> All theoretical chemistry is really physics; and all theoretical chemists know it. -- Richard P. Feynman A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
