need transformer source

[terrymorris]

I am in need of a step up transformer. I need to up AC line by two amounts (2 secondaries) if line voltage is 120, I need 135 & 150. It will be used for small motors and so needs to handle up to 3 amp draw for a half second and run at about 1 amp continuos.<p>I would like it to be as small as possible. We were using some that came from a surplus place, they had no markings so I have no idea where they came from. They are about 2.25" square and I need to keep them in this size if possible.<p>If you know of a source please let me know, preferably a sustainable source. I would like to be able to order 20 at a time a few times a year,<p>Thanks!

[Chris Smith]

Try "pico"?<p>They make small units that fit a lot of different voltages.

[rshayes]

If you do not need isolation or separate secondaries, you can use a 110 volt to 30 volt center-tapped transformer as an autotransformer. Basically, the 110 volt winding is connected across the line and the secondary is connected in series woth the line to get 150 volts. The center tap will give you 125 volts. The secondary current rating would have to be a little over 1 amp. The starting load is so brief that the transformer would not heat up significantly. If the motor tends to stall, a higher secondary currrent may be needed, along with careful fusing. This type of transformer might be a stock item. I would look at Signal Transformers. I think they may make units with 30 volt secondaries.<p>If you need isolated windings, you are up the well known creek with out a paddle. Those secondary voltages are not common values. You might find a control transformer with a split, multivoltage primary designed for stepping 220 VAC down to 110 VAC. This could be operated in reverse. Usually the primary taps don't go as high as 150 volts.<p>A last alternative is to have the transformers custom wound. There are several companies that will do this sort of work in the Los Angeles area, but I don't think they will be cheap. You might have to buy 50 or 100 to get a reasonable price.<p>[ May 09, 2005: Message edited by: stephen ]</p>

[bridgen]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>If you need isolated windings, you are up the well known creek with out a paddle.<hr></blockquote><p>You can connect in series the secondaries of separate transformers to get whatever voltage you need.

[terrymorris]

Stephen,<p>I do not need isolation so your idea should work for me. I would appreaciate you looking to see if signal carries one.<p>Thanks!!

[rshayes]

I thought that Signal might make something usable but I couldn't find it.<p>Other possibilities that will be close are 28 VCT and 36 VCT.<p>A 28 VCT transformer will give you 120, 134, and 148 volts.<p>A 36 VCT transformer will give you 120, 138, and 156 volts.<p>The Mouser web site (www.mouser.com) lists several of this type of transformer in various current ratings. Both Triad and Stancor make this type of transformer, and some of the other manufacturers they handle may also make similar parts.