On Wednesday 21 November 2012 15:46:42 Peter Blodow did opine: > Gene Heskett schrieb: > > /snip/ > > > But I wanted something at about 40 volts for the lathe & wound up > > making an unregulated linear for 10% of the cost of a switcher at the > > time. Loaded up, its doing about 37 volts so I missed my target, but > > it gets the job done, moving the lathe at very good speeds. The > > linear runs hotter, but both are working well. > > > > Cheers, Gene > > Gene, > large iron cores of the size you are working with have more than one > volt per turn which makes it easy to add some extra voltage. So why not > thread a foot or so of copper wire (or stranded cable) more through the > yoke to come up to your desired 40 volts? Living largely of junk yard > material, I did this several times. I f there was no room left for > wires, I took a lenght of thin copper strip cut from old tube shieldings > and soldered to lenght, and added two or three turns to the secondary in > order to increase the output voltage. To a 2 kW, 10 volts transformer I > added two turns of rather heavy rain drain copper sheet to boost it up > to 12.5 volts for an instant car starter (plus a selenium rectifier of > the good old kind which can take starter current). Insulate with wax > paper or preferably temperature resistant PTFE caulking tape or glass > fiber foil. > > Peter > I get the impression that the core of the one I am using ATM wouldn't be amenable to such. A, the windows are full, and B I think the iron is already right at saturation and may be responsible for a good portion of the heat I'm getting. 20 mins after powerup, the core is 30F hotter than the windings my IR reader can see. If it wasn't well varnished, lamination rattle, aka mechanical hum would probably be more noise than I'd like. So I keep a 6" rotron on the box when its running else the MM542's in the box would have their capacitors life noticeably shortened.
I'll stumble over a toroid I can use _and_ afford at some point. In the meantime it is working. Generally I have had good luck 'adjusting' a toroids output, both at 60 hertz, and at 70 kilohertz in one supply I designed from scratch in '80. E/I core stuff, not so much. The new steels of the last 35 years help, but generally the makers don't use a gram of it they don't have to. :( 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! I have always noticed that whenever a radical takes to Imperialism, he catches it in a very acute form. -- Winston Churchill, 1903 ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
