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# Creating a AC to AC step up transformer

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#### Slowdowns

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if you look around on the internet you find basic diagrams or piictures of transformers that shows there are usually 2 coils primary (in) and secondary (out). I was wondering how do you connect the primary ac coil to a ac powersupply, is it one lead from each end of the coil to each pole + - or do there need to be a resistor , diode or somthing. in front or behind the coil or maybe even the negaive unconnected but doesnt current need to flow to make a magnetic field.

If the transformer has been properly designed, you should be able to connect it directly to your AC terminals. (BTW, when referring to AC, there is no positive and negative +/-, only Active/Hot and Neutral), and yes, there must be a current flow :lol: otherwise there can be no power (energy), as we know that power = current x voltage (P = VI).

basically, any transformer, either step up or step down, is made with 2 separate coils of wire, wound around the same metal base. One coil is called the primary, and the other the secondary. The ac voltage source is always connected to the 2 leads of the primary coil only. As the ac signal moves through the coil, the electro magnetic field it produces transfers the current and voltage to the secondary coil. The 2 leads from the secondary winding are the output leads, which have the desired voltage and current, or the desired signal. The 2 coils are never physically electrically connected in any way, the coils are insulated from each other. They are only wound on the same conductive form. This is called inductive coupling.

A step down transformer has more turns on the primary coil and less on the secondary. A step up tranformer has more turns on the secondary and less on the primary. The ratio of turns between primary and secodary determine how many volts are stepped up or down, ie, 100 primary to 10 secondary (100:10) would step down 120 volts to 1.25 volts. If the ratio is listed, the first number is always the primary coil.

Note: The ratio of turns on a -former does not indicate how many turns there actually are in each coil, it is simply the mathematic ratio of the number of turns between the two coils.

Many transformers do not list the turns ratio, only the primary input/secondary output voltages. Small audio and signal-type transformers are rated by impedances, like 1k impedance primary to 8 ohm secondary.

Also, as voltage is stepped down, the available current is stepped up, and as voltage is stepped up, the available current is stepped down. It is an even exchange.

Edit: however, safely supplying the max available current is still limited by thickness of wire, rating the other components, etc.

I think I read too much into your question. Phasor's answer is a better one, and I concur. I makes no difference on which wire you connect from the primary coil to the hot and nuetral ac wires, there is no real polarity. It is only significant if you intend on grounding one of your wires to a chasis.

may be not

hamfiles said:
basically, any transformer, either step up or step down, is made with 2 separate coils of wire, wound around the same metal base. One coil is called the primary, and the other the secondary. The ac voltage source is always connected to the 2 leads of the primary coil only. As the ac signal moves through the coil, the electro magnetic field it produces transfers the current and voltage to the secondary coil. The 2 leads from the secondary winding are the output leads, which have the desired voltage and current, 0

not really, auto transformers are also there

abhishek

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