the only thing you have to be careful of
is that the insulation is sufficient for tube operation -- let's say you have a 120 VAC primary and 24V secondary and you have instead hooked up the secondary to the mains. There will now be 600VAC on the "new" secondary -- this is the point at which the insulation may begin to break down (I take data from USA Cable). Keep in mind too that your line voltage will swing over 10% during the day.
This shouldn't be a problem until you get to over 600V on the secondary. At any rate, fuse the darn thing and make sure to place the little rubber pad which comes with the torroid underneath it as a further bit of insulation.
Reversing transformers from their intended application has been used from time immemorial to derive bias voltages or obtain a regulated voltage.
is that the insulation is sufficient for tube operation -- let's say you have a 120 VAC primary and 24V secondary and you have instead hooked up the secondary to the mains. There will now be 600VAC on the "new" secondary -- this is the point at which the insulation may begin to break down (I take data from USA Cable). Keep in mind too that your line voltage will swing over 10% during the day.
This shouldn't be a problem until you get to over 600V on the secondary. At any rate, fuse the darn thing and make sure to place the little rubber pad which comes with the torroid underneath it as a further bit of insulation.
Reversing transformers from their intended application has been used from time immemorial to derive bias voltages or obtain a regulated voltage.
Uhm...
If you put more voltage (or a lower frequency) across a transformer than it's rated for, it produces a stronger internal magnetic field. Iron has a certain maximum magnetic level, known as saturation. To save space, manufacturers run their transformers close to the limits - close to saturation, for instance. Thus, any increase in voltage and/or decrease in frequency will cause saturation.
Now, what saturation is, is the iron is bottoming out, magnetically speaking. What happens electrically is the inductance goes phut, turning the winding from an inductor (which, in and of itself, draws little current) back into a plain wire. Thus, on saturation, you get a few ohms instead of several kohms, and this makes a *LOT* of heat. This will generally smoke the transformer, putting itself out of its misery. Of course, then you end up with a terrible odor in the room, a blown circuit, and a dead transformer.
Tim
If you put more voltage (or a lower frequency) across a transformer than it's rated for, it produces a stronger internal magnetic field. Iron has a certain maximum magnetic level, known as saturation. To save space, manufacturers run their transformers close to the limits - close to saturation, for instance. Thus, any increase in voltage and/or decrease in frequency will cause saturation.
Now, what saturation is, is the iron is bottoming out, magnetically speaking. What happens electrically is the inductance goes phut, turning the winding from an inductor (which, in and of itself, draws little current) back into a plain wire. Thus, on saturation, you get a few ohms instead of several kohms, and this makes a *LOT* of heat. This will generally smoke the transformer, putting itself out of its misery. Of course, then you end up with a terrible odor in the room, a blown circuit, and a dead transformer.
Tim
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