Building a transformer
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From: sparc on 10 Aug 2006 15:03 u know ...if u really wish to "learn" ...why dont you design yourself a 50A, 0-50V continuously variable SMPS ....capable of operating in both CV and CC modes. (i know what some ppl are going to say ....he wants to learn ...not repent)
From: GregS on 10 Aug 2006 15:10 In article <1155236593.315019.111670(a)b28g2000cwb.googlegroups.com>, "sparc" <sparc_001(a)yahoo.com> wrote: >u know ...if u really wish to "learn" ...why dont you design yourself a >50A, 0-50V continuously variable SMPS ....capable of operating in both >CV and CC modes. > >(i know what some ppl are going to say ....he wants to learn ...not >repent) > I have a HP 6268B here with a bad transformer. I didn't even think of rebuilding the transformer. Well it did do 0-40 volts at 0-30 amps. I just recently got the idea to buy another used transformer at some reduce specs to install in the beast. Hmmmm. greg
From: Mark Fortune on 10 Aug 2006 16:08 sparc wrote: > u know ...if u really wish to "learn" ...why dont you design yourself a > 50A, 0-50V continuously variable SMPS ....capable of operating in both > CV and CC modes. > > (i know what some ppl are going to say ....he wants to learn ...not > repent) > Given the replies i've had on this, it seems the more sensible way of going about it. Whilst i'm sure I will enjoy with experimenting with transformers in the future, building a power transformer - specifically the beast i'm after does seem to be costly and time consuming going by the responses i've had on this thread, and is unlikely to work (first time around anyway), where in contrast I could just pick up old/broken equipment at the local car boot sale for under a fiver. I've had a little read on (very basic concepts of) switching mode power supplies, and this does seem to way to go in terms of efficiency and size. So yes, forgive me for my sins, I repent! ;) Thanks to all those that offered their advice however, it's been insightful to me, and I certainly wont give up the opportunity to build my own transformers in future... just not on such a power crazed level where there are better solutions. Regards, Mark
From: David on 10 Aug 2006 16:19 "Mark Fortune" <mark(a)fortrex.co.uk> wrote in message news:44db929f$0$31649$db0fefd9(a)news.zen.co.uk... > sparc wrote: >> u know ...if u really wish to "learn" ...why dont you design yourself a >> 50A, 0-50V continuously variable SMPS ....capable of operating in both >> CV and CC modes. >> >> (i know what some ppl are going to say ....he wants to learn ...not >> repent) >> > > Given the replies i've had on this, it seems the more sensible way of > going about it. Whilst i'm sure I will enjoy with experimenting with > transformers in the future, building a power transformer - specifically > the beast i'm after does seem to be costly and time consuming going by the > responses i've had on this thread, and is unlikely to work (first time > around anyway), where in contrast I could just pick up old/broken > equipment at the local car boot sale for under a fiver. I've had a little > read on (very basic concepts of) switching mode power supplies, and this > does seem to way to go in terms of efficiency and size. > > So yes, forgive me for my sins, I repent! ;) > > Thanks to all those that offered their advice however, it's been > insightful to me, and I certainly wont give up the opportunity to build my > own transformers in future... just not on such a power crazed level where > there are better solutions. > > Regards, > Mark Also realize 50A at 50V is 2500 watts at 100% efficiency. If you are in the USA, you will need a 220V power connection to do this. David
From: wrongaddress on 10 Aug 2006 16:31
Rich Grise wrote: > On Tue, 08 Aug 2006 22:53:34 +0100, John Woodgate wrote: > > > In message <Uf7Cg.6098$vl5.3392(a)newsfe4-win.ntli.net>, dated Tue, 8 Aug > > 2006, ian field <dai.ode(a)ntlworld.com> writes > >>You can't beat a microwave oven transformer with a secondary > >>transplant! > > > > That depends on how the leakage inductance is produced, and whether you > > can remove it, which you must in order to use it as a conventional > > transformer > > Taking out the old secondary is almost trivial, with a hacksaw and a > chisel. ;-) > > But apparenlty, you need to add windings to the primary to bring the > magnetizing current down, or somethiing like that. I have an old MOT > that I've been experimenting with, and the idling current is just way > too much for any self-respecting 60 Hz trannie, albeit they do have > to account for the shunts, which current-limit the output. > > On and off, I've been poking around with this thing, but now I'm at > a crossroads with it - do I cut it open, take the bobbin out, and > enhance the primary that way, or do I thread more #18 Formvar wire > through it until I build up another layer of windings? So far, > threading the new wire through has turned out to be much more of > a PITA than I had expected, so it's kind of on the back burner for > the moment. > > Good Luck! > Rich Yes, you need about 50% more wire on the primary to get the idle current down from 3 amps. I think microwave transformers go into saturation with no load. Another problem is the iron laminations are all welded together on the base plate, so the iron gets hot from the huge eddy currents. Probably better to use some other kind of transformer. I have one from an old pin ball machine that idles at 10mA with no load. -Bill |