about Transformers

[Ziddik]

So I think we've established that you connected the two transformers as shown in Fred's power supply, not as you had originally described it. In other words, you connected them back-to-back (i.e., tied the secondaries together).

You should be able to figure out how this would work, keeping in mind that a transformer works in both directions.

You basically built a 1:1 isolation transformer consisting of 2 xfrmrs.

Why would you think you'd be able to use this to save electricity? You can't create something out of nothing.

Fred's circuit uses the transformers to isolate his power supply from the power line for safety reasons. Otherwise, he'd just connect his bridge rectifier directly across the incoming line ("mains").

And yes, I'd be curious to know what you were trying to accomplish too.

i thought i could connect the output of 2nd transformeR to a TV Or DvD player..etc [bcz it takes only 12v and convertrts it to 230vAC so cant i use it to save some bill?..maybe not,.)

 

[carbonzit]

i thought i could connect the output of 2nd transformeR to a TV Or DvD player..etc [bcz it takes only 12v and convertrts it to 230vAC so cant i use it to save some bill?..maybe not,.)

You need to work this through and compute the power at each stage of the process. In fact, you could do just that: use your two transformers to power a 230-volt device that doesn't use much power, measure the voltages and currents and see what you get. (Remember that power = voltage X current.) Disclamer: I don't recommend actually trying this unless you know what the hell you're doing, which I can't say I believe, based on this thread (strictly for safety reasons, not to insult your intelligence).

Keep in mind that a transformer is not 100% efficient at transferring power, so you lose something at each transformer. Like they say, you don't get something for nothing.

 

[Ziddik]

Well, at least you didn't blow the transformer! Be grateful: you learned a lesson (hopefully) and all it cost you was one little bitty resistor. I'd consider that money well spent.

how can i blow them? It gets only 12vAC from the output of another same rated transformer! And is usualy capable to maintain the 12vAC in its secondary windings!! Aint it?

 

[BrownOut]

i thought i could connect the output of 2nd transformeR to a TV Or DvD player..etc [bcz it takes only 12v and convertrts it to 230vAC so cant i use it to save some bill?..maybe not,.)

Well, the fact that the 2nd transformer converts 12V to 240V doesn't mean you're gonna save on your electric bill. You're better off just plugging straight into the outlet. There is no way you can use any number of transformers to get more energy than you put in. However, if you had, say a variable line transformer, you might be able to run a few lights at reduced power to save a little. The savings probably won't offset the cost of the variable line transformer though. You might want to try looking into solar or wind power. That's reall the only way you're going to save, and even that won't be cheap.

 

[BrownOut]

how can i blow them? It gets only 12vAC from the output of another same rated transformer! And is usualy capable to maintain the 12vAC in its secondary windings!! Aint it?

Sure, but you were trying to deliever 175 Watts. Good thing the reisitor blew up before the transformer did. You have to know how much power you're delivering before you start plugging things in.

 

[carbonzit]

There is no way you can use any number of transformers to get more energy than you put in. However, if you had, say a variable line transformer, you might be able to run a few lights at reduced power to save a little.

Don't want to complicate things here too much, but running lights at reduced power may actually increase your power bill. (We're talking/writing about incandescent lights here, not CFLs.) While incandescent lights can last much longer at reduced voltages (like some of Edison's original bulbs that are still burning to this day), they're much more inefficient at reduced voltage and end up emitting more infrared (= heat) than light.

 

[BrownOut]

Doesn't matter what kind of light they emit. Power is volts*amps, independent of the kind of light. We've used this method to save on holiday lighting.

 

[Ziddik]

i understand it like what cz stated, i think the primary windings Of 2nd transformer will "FRY" if it used to power higher power devices like TV.. Maybe.. And I have not enough strength to watch a "transformer fireball"

 

[Ziddik]

cant i use a 12Vdc to 220v Ac Inverter to save some power as well as bill? I mean i connect a 12v transformer to the inverter's input instead of 12V battery! Does't it save some bill?

 

[BrownOut]

cant i use a 12Vdc to 220v Ac Inverter to save some power as well as bill? I mean i connect a 12v transformer to the inverter's input instead of 12V battery! Does't it save some bill?

Absolutely not! As I've previously said, there is nothing at all you can connect to your power to save on your bill. You need a renewable or free energy source ( solar, wind ) for that. You can probably save more by just changing your power usage habits, trun off lights and appliances when not in use, use switchable power strips for all your applicances so that they aren't drawing power when switched off, etc.

One of the biggest power wasters is the cable TV box. Mine is warm to the touch, even when it's turned off. Identify other appliances that are in "standby" when turned off, and make sure they are disconnected from you home power system.

PS: I should have mentioned inexpensive light dimmers along with variable line transformers. They are cheaper. For some reason, I have transformers on the brain. Also, use minimum light wattage necessary or CFL lighting if possible.

 

[Ziddik]

Are you both very sure that none of these things will't work? If not i am gonna power my junk TV using that transformer methode (as said in post#1) and will post results tomorrow only if i am alive or i did't burn my house down!...!!!

 

[BrownOut]

Been nice knowing you.

 

[carbonzit]

i understand it like what cz stated, i think the primary windings Of 2nd transformer will "FRY" if it used to power higher power devices like TV.. Maybe.

Maybe, maybe not.

You need to sit down and do some calculation.

You say your transformers give 12 volts @ 5 amps. Fine. Let's call that 60VA (volt-amps).

That's all the available power you have to run anything without overheating the transformers. In other words, not very much. (Think 60-watt light bulb.)

Let's look at what happens if you try to run a bigger load, say a computer that uses 200VA.

You connect the computer to the secondary of the 2nd transformer, where it tries to draw 230 volts at 870mA (230 X 0.87 = 200). Back on the primary side of the 2nd transformer, this translates to 12 volts at 16.7 amps.

Now, do I really need to go on with this example? Can you see what's wrong with this picture, and why it won't work?

 

[Ziddik]

FAIL!! i connected my tv to the output of the TX,s primary.. It did't work and tried to connect my 5.1 amp.. It worked (very low voltage) but could't turn on even my USB player that works from 5vDC.. Complete fail

 

[carbonzit]

OK, so tell us why you think it didn't work.

It ain't worth beans unless you learn something from it.

 

[Ziddik]

So what if i connect a 12v 5 amp transformer(into secondary winding) in the output of an amp and connected its primary to a speaker? Could it double the voltage?

 

[Reloadron]

So what if i connect a 12v 5 amp transformer(into secondary winding) in the output of an amp and connected its primary to a speaker? Could it double the voltage?

No it will not double the voltage. Unless the transformer has a 2:1 ratio. Even then there is a problem.

The transformers discussed till now in this thread have been power transformers designed for use at frequencies or 50 / 60 Hz. They are not audio transformers designed to work at audio frequencies. There is a very big difference between the two.

There is a very old proverb that applies here about placing the cart before the horse.

Trying to employ the use of transformers without an understanding of transformer theory is a fruitless experiment in frustration. Learning electronics starts with what is called Electronics 101 in the US and this applies globally regardless of what we choose to call it. It begins with learning DC theory and even before that the fundamentals that electronics are built on. Jumping into transformers without all the basics is about like jumping into the real deep end of a swimming pool before learning how to swim. Bad things happen.

Initially you connected two transformers "back to back" and placed a resistor and LED across the output. What you did as was pointed out was went from mains voltage (220 Volts) down to 12 Volts then back up to 220 volts. Bad things did happen.

Connect your transformers that way again, leaving the load out. Let them sit a few min. Can you hear them buzz? Place a finger on them, are they getting warm to the touch? The heat you feel is power loss before a load is even applied.

Ron

 

[Ziddik]

what is the difference between audio and power transformers? What is the use of audio transformers?

 

[Reloadron]

You really do not want to start at the beginning do you?

1 Audio Transformer Basics
Since the birth of audio electronics, the audio transformer has played an important role. When compared to modern miniaturized
electronics, a transformer seems large, heavy, and expensive but it continues to be the most effective solution in many audio
applications. The usefulness of a transformer lies in the fact that electrical energy can be transferred from one circuit to another
without direct connection, and in the process the energy can be readily changed from one voltage level to another. Although a
transformer is not a complex device, considerable explanation is required to properly understand how it operates. This chapter is
intended to help the audio system engineer properly select and apply transformers. In the interest of simplicity, only basic concepts
of their design and manufacture will be discussed.

I suggest you read this link. If you can't understand what is covered including the math functions you need to go back to the beginning which is what I was getting at as to EL101.

Then we have Power Transformers:

Power Transformer Design
This Section covers the design of power transformers
used in buck-derived topologies: forward
converter, bridge, half-bridge, and full-wave centertap.
Flyback transformers (actually coupled inductors)
are covered in a later Section. For more specialized
applications, the principles discussed herein
will generally apply.

So I suggest you read this link.

The questions you are asking involve pages and pages of text to answer. There is no one simple explanation and to understand the explanations requires a working knowledge of the basics.

Ron

 

[crutschow]

One thing you seem confused about is conservation of energy, which all transformers do. You can never get more power out of a transformer then you put in. You can increase the output voltage, for example, but that will reduce the current by the same proportion, so the energy out still equals the energy in (neglecting transformer losses).