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Isolation transformer

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PostPosted: Mon Dec 11, 2006 10:39 pm    Post subject: Isolation transformer Reply with quote

Hi Folks. I,m about to build an isolation tranformer from an old tube tv tranformer that i've got from a scrap yeard,
and connect it in conjunction with a Simple Series Power Limiter that i also built,put it inside the same box.
Now i'd like
your technical know how and help on this.Ok the transformer has INPUT-120v and three outputs, 126v,19v,17,now is it practical
to use this as a isolation transformer? also can i use a 2Mohms resistor from the primary to the secondary? and a 5 Amp fuse?also
could i use one of the other 17v.19v outputs to regulate the voltage? and build an ammeter?. THankyou in advance
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Joined: 08 May 2006
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PostPosted: Tue Dec 12, 2006 4:04 am    Post subject: Reply with quote

Isolation txformer is basically a 1to1 ratio device that only seperates the two ground planes . Yes you can use the 126v tap as an isolated source as long as you do not exceed the current capability of the txformer.

Not sure I understand the bit about using other taps for regulation & to build an ampmeter? ---don't follow you. In general, a txformer can not provide "voltage regulation" of any kind by itself. You'd need some sort of control/feedback to achieve voltage regulation as in a SMPS (switch mode power supply)
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PostPosted: Sat Jun 02, 2007 1:40 am    Post subject: isolation transformer Reply with quote

Hi Frank,

I have built an isolation transformer with two identical tube TV transformer back to back. I am not sure your transformer is good because in the process of building my isolation transformer, I measured the output voltage of 7 old transformers. I get for 120V input, an output of 13V and an output of 350V on all 7 transformers. So my set-up is very simple: the 350V out from the first transfo feeds the 350V of the second transfo, and the output of the second transfo gives me the 120V I need.

I use this isolation transformer too feed my oscilloscope (50Watt)for servicing, and I should have made one before. It works fine!

I would like to send you a pic of this, but I don't know how to do...

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