On Thursday 22 November 2012 01:07:50 cogoman did opine: > On 11/20/2012 11:28 AM, Gene Heskett wrote: > > 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. > > A little trick that just might get you to that 40 volts. > > 1. Find out what the max input current of the power supply is. > 2. find a wall wart 5 volt transformer that puts out 5 volts at the > current specified in step 1 (it must be a linear wall wart). > 3. Wire the primary of the wall wart to your AC in. > 4. Wire the secondary of the wall wart between one side of the AC > input, and one side of the power suply transformer primary. The > goal is to have the 5 volts AC boost the line voltage to the main > transformer by a marginal amount, and increase the output DC > voltage. If the output DC voltage gets lowered, simply reverse the > leads on the 5 volt transformer secondary. > I have done such in the past, most recently in the old supply that ran the mill for several years. In that case I added a 12 volt 3 amp to feed nominally 135 volts, into the 95 volt primary tap, and got around 29 volts out of a nominally 24 volt transformer. A big old potted monster from a 2" video tape machine made back in the mid-60's, an RCA TRT-1. Despite the obvious attempt to saturate that puppies core, I don't think I ever detected more than about a 10F rise in its temp. I still have it, but its now holding down a spot on the floor in back of the bandsaw. I have periodic bouts of fancy about building a rolling table and frame to do some fawncy resawing with it since it can resaw a 13" log, into 1/16" veneer sheets if I do it right. Dreams that involve measuring the power draw of the driving motor, and adjusting the stepper driven table speed to keep it running at about 75% load, over an 8 to 10 foot x motion range. When that gets too slow, then its time to put on a fresh Wood Slicer blade, those are phenomenally smooth and fast cutting blades.
However, ATM, I really need to clear out the garage a bit and get the woodworking stuff moved to the garage. Wood and metal don't mix, the sawdust settles on the metal, is usually a little damp and the metal turns bright red with rust very quickly if the dew point gets near. WD-40, vactrol, stp, nothing seems to stop it. 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'm not offering myself as an example; every life evolves by its own laws. ------------------------------------------------------------------------------ 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
