How to increase AC current without using amplifiers and external power source?

Iam having 12V AC and the current 100mA.When i apply the 12V AC to secondary winding of 5V transformer.The voltage gets boosted up to 64V.I don't want voltage to be boosted,instead i want to increase the AC current without using transistors,external power sources,etc.Like the transformer which is boosting voltage when applying AC voltage at secondary.I need to increase AC current only and not the voltage.I want these to be done without using amplifiers.Because amplifiers uses external power source.Any one tell me how to increase current.Otherwise is there any way to increase AC current by reducing the voltage?

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iceng12 days ago

You need to learn about transformers.. Click on the first picture to see A=Bifilar winding usually they are side by side read about them here . B=Common standard winding with the lower voltage, higher current larger wire size secondary winding green which is protecting the fine wire primary red winding from physical damage, which easily occurs in smaller transformers shipping.. C=High voltage isolating winding by physical separation.. D=Dual windings for better quality machine made transformer windings. Like Jack A Lopez shows in his soldering gun pointer. See also the 6th picture...

The 2nd, 4th and 5th pictures show [ E-I ] shape transformer laminations because of their they resemble capital letters E & I which are necessary for improving magnetic efficiency by limiting energy robbing eddy currents..

Regarding increased current the 8th picture shows an example of lower voltage line transformers like 110V primary in series across a 220VAC Main while the secondaries are in parallel to double the current of just one transformer... Then in the 7th picture we see a circuit schematic of variable auto transformer that adjust drives a 24 Volt transformer whose secondary current will heat a welding rod just enough to slice foam... See also How to drive current to hot wire cut styrofoam in Step_3

TTT.GIFWindingsCROSSSECTION.PNGinduction-heater-water-coil-assembly2.jpgEI1.JPGE-I_core.gifEI_transformer.jpgstep-downwire heater.gifStepDown.jpgترانس_جریان

For an ideal transformer, the input power is equal to the output power.

Pin = Vin*In = Vout*Iout = Pout

and also
(Vin/Vout) = (Iout/Iin) = (Nin/Nout)

where (Nin/Nout) is the ratio of, turns on the output winding, to, turns on the input winding. Sometimes that is just called the, "turns ratio"

These same equations can be found at the begining of the Wikipedia article for "Transformer"

There is a little box on the right side of that page labeled "Ideal transformer equations"

Real transformer performance is of course, not exactly the same as the ideal transformer, but the math, the equations, for the ideal transformer is a lot easier.

Anyway, it turns out it is possible to use transformers to make large AC current. I mean, a transformer that can produce current in the secondary that is 10s or 100s of times larger than the current in the primary. (With an inverse-proportional change in voltage; i.e. the magnitude of output voltage across the secondary is 1/10ths or 1/100ths that of voltage across the primary.) Typically these transformers will have hundreds of turns of thin, or medium sized, wire on the input winding, and just one or two turns of very thick wire for the output winding.

Also I can show you some pictures of transformers wired this way. The first example is this picture,

from the Wikipedia article for "Soldering gun"

This kind of soldering gun is essentially a transformer wired to make big current in its secondary winding.

The King of Random's (KOR's) homemade spot welder from microwave oven transformer (MOT) is another example of a transformer with very big current flowing in a 1 or 2 turn secondary.

Actually this site has more than one spot-welder-from-MOT instructable. Here is another one:

I also found a couple of homemade soldering gun instructables. Again, these seem involve taking apart an old transformer, and installing a new secondary winding, with fatter wire and fewer turns.

You're trying to violate the conservation of energy rules.

iceng12 days ago

So as a BEginner Electronic communicator you should know what every real engineer knows, Energy cannot be created... Energy however can be dispersed and wasted...

So increasing current without changing voltage VIOLATES the above statement..

Get or wind a 10:5 transformer to double your AC current and half your voltage, similarly (easy to get) a 10:1 transformer to increase your current by almost ten and decrease your voltage by a factor of ten...

You should not assume we know your AC frequency which would allow defining a minimum iron E-I lamination crossection and then turns and wire size..

OK Voltage up current down.

Voltage down current up.

However you can't just reverse a transformer to achieve your goal.

Think in watts.

Watts are volts times amps.

So if you want 100 watts at 12 volts that is 100 / 12 you need 8.33 amps.

If you need 100 watts at 6 amps that is 100 / 6 you need 16.66 volts.

You never said the watts you need.