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
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
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
--------------8 So yes, forgive me for my sins, I repent! ;)
Wow, pretty sure i'm not going to need 50A at any voltage... not sure where that came from as originally I only wanted 10A. Incidently though, im in the UK so we have 230V by default.
All Pro-Electron numbered devices beginning with "A" are Germanium!
Not to mention the heatsinks it'll take when you want to deliver, say,
12 volts at anywhere near that 50 Amps. Hint: Plan on a fan and wheels.Isaac
I'd also query the need for such a large bench top supply - unless you're regularly repairing or building things like power amps.
--
*The man who fell into an upholstery machine is fully recovered*
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
aha, you've discovered one of my planned future hobbies :) any money in it though?
In message , dated Fri, 11 Aug
2006, Mark Fortune writes
Yes, you'll spend quite a bit.
Everybody and his dog makes power amplifiers. Try something else (which is small-signal and thus less likely to emit flames and smoke). For example, low-level active crossovers; 2-way, 3-way, 4-way, Butterworth, Linkwitz-Riley, Bessel, transitional Gaussian, Thiele....
Enough to keep you busy for 50 years. And there isn't a great deal of competition, at sensible prices, so you could sell a few on Ebay. There is other low-level stuff which, compared with power amps, is a doddle to get working if you master the design mathematics.
And you only need a +/- 12 V power supply at 10 mA. (;-)
-- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
Is there REALLY a market for active crossovers?
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
In message , dated Fri, 11 Aug 2006, Jim Thompson writes
The industry as a whole is slowly coming round to the realization that some of us have had for a long time, that active crossovers are the only ones that work properly, are extremely cheap and can be designed without a lot of fiddling. The extra amplifiers required are cheaper than the equivalent passive crossover.
Besides, do you want to build a 4th/8th-order Linkwitz-Riley 3-way using passive components? (The midrange section is a bandpass filter so has to be 8th-order.) You will also need Zobel networks (accurate ones) for each driver, so as to properly terminate each filter. BIG, costly components. No electrolytic capacitors, of course, because you need
+/-5% tolerance or better.-- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
I ran across info on rectifier design up through filtering (but not regulation) at:
A paperback book for transformers: Practical Transformer Design Handbook; Eric Lowdon; published by Howard W Sams; 240 pages; 8x11"; my copy is 1981. It is aimed at experimenters designing single transformers using salvaged cores. I thought it was very good. It may be hard to find, but with the internet who knows.
bud--
I've never found large bench supplies helpful for designing power amps.
Graham
Not as much as you might think.
Graham
10mA ? That'll power a pair of 5532s !
Graham
In the pro-audio market for sure.
Graham
Good link, Bud! Thanks!
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
In message , dated Fri, 11 Aug
2006, Eeyore writesNot only. Of course, all the while the consumer industry can get away with a 2 uF in series with a tweeter with no magnet to speak of, why bother with active crossovers? But these things DO percolate down.
-- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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