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 Post subject: isolation transformer
PostPosted: Oct Mon 11, 2010 6:41 pm 
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Location: Wisconsin
I had a good day at the swap meet and found 2 transformers. They are rated at 24v out, and have a 1.65 amp rating.

My questions are, do I need to fuse these somewhere? I have a variac I plan to include in the supply somewhere. It seems there was a debate in the past as to the order of transformer and variac placement.

The other question is, will these be able to handle enough wattage for most radios? My variac is rated at 1 Amp I think. I will have to check the rating for sure of the variac but if I figured correctly, with both transformers and the variac that would put me at about a 100 Watt limit. Am I missing something or does that sound about right?

Thanks,

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 Post subject:
PostPosted: Oct Mon 11, 2010 6:45 pm 
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I would say maximum of 40 watts or a basic AA5 radio (about 30 watts).
The nice thing about aa5 is you could put 95v in and still operate normally.

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 Post subject:
PostPosted: Oct Mon 11, 2010 6:50 pm 
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I'm not 100% clear on what you are trying to do. Were you--for example--thinking of running the 24v side from the variac?

First, the 1.65 amp rating on the 24v output gives you a power rating of 39.6 Watts. This will not be enough to run many radios. You could run the 24v transformers in parallel, and then you'd have ~79Watts

More generally, you need to layout the connections and then calculate the power in each portion of the circuit and see if it is withint the ratings of the component.


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 Post subject:
PostPosted: Oct Mon 11, 2010 7:06 pm 
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I was going to run them back to back for 100-125 volts out. Others have used this method for creating an isolation transformer from what I understand. That is what I'm looking into. It would just be used on transformerless sets.

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 Post subject:
PostPosted: Oct Mon 11, 2010 7:51 pm 
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You should just buy an isolation transformer and forget about using 2 transformers.


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 Post subject:
PostPosted: Oct Mon 11, 2010 8:11 pm 
Silent Key

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You could parallel the primaries, and series the secondaries,
and use the vatiav from 0-50 volts each secondary 2 amp fuse.
AND 1 amp fuse on Variac line cord.

Do these transformers have a Class rating or are they
for a special purpose ? If so they might have a surprise in the core.

When you are done see what happens as you slowly light a 100 watt bulb.

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 Post subject:
PostPosted: Oct Mon 11, 2010 9:03 pm 
Silent Key
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milkman64 wrote:
I was going to run them back to back for 100-125 volts out. Others have used this method for creating an isolation transformer from what I understand. That is what I'm looking into. It would just be used on transformerless sets.
This certainly works, but you'll be limited to the power rating on those 24-volt windings, minus some allowance for losses. The setup will probably not be good for much over 35 watts--- a bit more for very short periods.


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