Transformer with Frequency?

[walters]

1.) when i raise the frequency on AC Generator hooked to a inductor the Voltage goes down?

    so Frequency goes UP
    inductor voltage goes down for the inductor output


2.) I hook up a Transformer for my seconded test

    a.) i raise the Frequency on the AC Generator and the voltage
      on the secondary side of the Transformer stayed the same
     i was shocked y i asked its an inductor what makes it
     have the Same voltage on both sides of the transformer
     where the inductor by its self the output lowered the voltage
     by not with the Transformer the Primary and Secordary have the
     same voltage even if i Raise the Frequency all the way up no cut off
      frequency doesnt reach .707 at all

3.) Does anyone know  ?

4.) I thought a Transformer was a inductor ? but it doesnt give a
     voltage drop even if frequency is raised ?

[niftydog]

how are you measuring this?

Have you taken into account self capacitance (and hence resonance) or other stray circuit elements?

More info would be needed before one could postulate.

[walters]

1.) Function Generator at AC 1Khz say 10V AC
2.) I put the inductor to ground and and to the Function Generator
3.) put the RMS multimeter across it to measure voltages
    across the Inductor

4.) I measure the voltage its 10V AC
5.) i Raise the AC Frequency
6.) The voltage starts to Drop from the inductor my meter in parallel
     across the inductor

so AC freq goes UP
voltage goes down


I do the same but put in a Transformer
i raise the AC Frequency and the voltage Doesn't change at all
its 10V on primary and Secondary no drop at all
Why is this no voltage Drop?
when i raise the Freq to the transformer?

[Rob Strand]

I thought a Transformer was a inductor ? but it doesnt give a
voltage drop even if frequency is raised ?

A transformer is not really inductor.

A real transformer will look like a large inductor if you use one pair of terminals alone ie. not using it as an transformer where you put input on one set of terminals and look at the voltage on the other set.

If you use one set of terminals and short the other terminals a real transformer will also look like an inductor but the inductance is *much* lower then when the second terminals are open.

[walters]

1.) no im putting AC 10 Volts on the Primary side and Measuring the
    the Voltage with the Multimeter on the Secondary Side
    and there is no Voltage Drop when i raise the freq up ? Why is that ?


2.) where the plain old inductor when i raise the freq up
    and measuring the voltage it drops .707

3.) The Transformer does Voltage drop with u raise the Freq up
    Why is that ?

[niftydog]

again, far too vague to allow useful comment.

What's the value of inductance?

What's the input impedance of your multimeter?

What's the source impedance of your signal generator?

etc etc etc.

im putting AC 10 Volts on the Primary side and Measuring the
the Voltage with the Multimeter on the Secondary Side
and there is no Voltage Drop when i raise the freq up ?

The Transformer does Voltage drop with u raise the Freq up

This is a direct contradiction.  :shock:

[walters]

I missed spelled sorry it Doesn't

[niftydog]

Also, to test this properly you need an oscilloscope. Your multimeter isn't designed to measure those frequencys. I'd be willing to bet that your multimeter is a major cause of your confusion.

Reactance of an inductor goes up with frequency, so in an ideal world you'd expect the voltage to rise as well. However, inter-turn capacitance and other stray circuit elements are likely to affect this unpredictably.

[walters]

1.) No im just measuring the Voltage not the Frequency the output  
    of the transformer Secondary side?

2.) just measuring AC voltage output

[walters]

1.) is has to do with Frequency and amplitude measurements
    so like Freq vs ampliture or voltage output "?"


2.) Record each value of frequency? and Voltage output ?


3.) Rules for the inductor measurements
                a.) Frequency goes Down
                b.)  XL the Inductance reactance goes down
                c.) the Voltage output goes DOWN
        d.) the current goes UP

4.) Rules for the Mutual Inductance?
                a.) Frequency goes Down
                b.) XL  " Cancels" i think
                c.) the voltage output is the SAME on both Primary and Secondary
                d.) and the current is the Same also on both primary and Secondary

5.) Rules for the Mutual inductance?
                a.) Frequency goes UP
                b.) XL " Cancels" i think
                c.) the Volage output is the SAME on both Primary and Secondary

6.) Why is it the SAME AC voltage on both sides of the mutual inductance "?"
    if i raise or lower the Frequency and Amplitude doesnt change at all "?"

7.) With the inductor by itself and you lower the Freq the AC output or Amplitude
     goes DOWN but not with the mutual inductance ?

8.) Why didn't the mutual inductance have a Lower Amplitude when i Lowered the Freq?

[niftydog]

just hold on to your horses there, walters. You're rapid fire questions are starting to get me offside and you don't seem to be absorbing the answers I'm giving you!!! Please, take it one step at a time, ok!!!

No im just measuring the Voltage not the Frequency the output
of the transformer Secondary side?

irrelevant. You're measuring an AC voltage and multimeters do not do this well. Most multimeters are designed to measure AC voltages at around 50-60Hz. They do not cope well with high frequency voltages.

to test this properly you need an oscilloscope.


Inductive reactance = 2pi x frequency x inductance.

a.) Frequency goes Down
b.) XL the Inductance reactance goes down

yes

c.) the Voltage output goes DOWN
d.) the current goes UP

not necessarily. Have you forgotten ohms law?!?

Your last post makes absolutely no sence whatsoever and I am now totally uninclined to try to help you any further.

This is not the appropriate forum to be asking such questions, please visit one of the many other forums dealing with general electronics theory and come back when you have a question specific to stompboxes!

[walters]

1.) Well what happens then in my electronic book it says that
    or maybe the book is wrong


2.) Freq UP
    XL goes UP
    Voltage  "?"

[niftydog]

text books describe the ideal component in the ideal world. Real inductors don't always act that way.

besides all of that, you cannot and should not trust your multimeter to be taking these measurements! Get access to an oscilloscope and try your experiements again.

As frequency goes up the voltage depends on both the current and the reactance, reactance in turn depends on both frequency and inductance. Meanwhile, other elements such as interturn capacitance and parasitic resistance also play a part - so it depends on the combination of all of these as to what is actually happening.

[walters]

1.) Well my Book says "im using a Oscilloscope to see Volts "L" out
 
Inductor Rules
       a.) Frequency goes DOWN
       b.) V out Decreases
       c.) it doesn't matter what the inductor value is its still going to
            Decreases the voltage if the Frequency goes Down
            just different Reactances vs value relationships with frequency

Mutual inductance Rules
       a.) Frequency goes DOWN
       b.) Look V out is the SAME---------"why is it the same?"
       c.) the Reactance "Cancels out"  "why does the reactance Cancel"

[puretube]

maybe the transformation of electrical energy into magnetical energy causes the F/V behaviour of a single coil;
and then the second coil of the transformer, which does the transformation from magnetical energy into electrical energy causes a reversed F/V behaviour;
ending up with an output that stays "constant" with frequency?
:?:  :idea:


BTW: in my textbook, the inductor behaves oppositely than described in your first post;
what you described (voltage going down with increasing frequency)
happens with a capacitor hooked from output of a generator to ground according to my book...

[Rob Strand]

A possible problem us most multimeters have a very non flat response above 2kHz or so.  To make matters worse the frequency response can be completely different on different ranges - same ranges may roll-off, others may boost over a span of frequencies.

[walters]

Yea im sorry i did do it wrong about the first post sorry

i fixed it now i had to read more in my book

thanks for your time for reading this tho

[walters]

1.) So why does mutual inductance voltage output stays "constant" with
     AC Frequency?

[puretube]

maybe the transformation of electrical energy into magnetical energy causes the F/V behaviour of a single coil;
and then the second coil of the transformer, which does the transformation from magnetical energy into electrical energy causes a reversed F/V behaviour;
ending up with an output that stays "constant" with frequency?
:?:  :idea:

according to above theory, the effects cancel thru the electrical to magnetical conversion and back.

I like this simplified idea - I`ll leave the mathematical/physical exact theory to those who have written that up hundred years ago...

[walters]

1.) Puretube thats the info i need it can u please give me it