Hi,
I understand it to be the other way round, as you drop impedance you
need more inductance, and the issues here are all at the treble end.
rgds, /sreten.
No. Load impedance and own transformer's inductive impadance are in parallel. If you drop load impedance in respect of own transformer's inductive impedance that means on the same frequency impact of transformer's inductive impedance on the resulting impedance is lower.
I don't see any fun in misinforming of forum members. Shame on you Pieter!
OK Wavebourn,
My location is Europe.
Right now I am on vacation in the USA; great country; FRIENDLY people.
I try to understand your last post but your formulation is so lousy that I don't understand what you are trying to say. So I guess your roots are not in the USA which might explain your pretty UNFRIENDLY behaviour.
Please point out clearly where and how I misinform our forum members, and please try to do this within the rules of this forum.
Pieter
Tribute Audio Transformers
My location is Europe.
Right now I am on vacation in the USA; great country; FRIENDLY people.
I try to understand your last post but your formulation is so lousy that I don't understand what you are trying to say. So I guess your roots are not in the USA which might explain your pretty UNFRIENDLY behaviour.
Please point out clearly where and how I misinform our forum members, and please try to do this within the rules of this forum.
Pieter
Tribute Audio Transformers
Dear Pieter;
however, English is not my native language, but laws of physics are international, and do not depend on country where applied, and on how friendly are people who apply it.
however, English is not my native language, but laws of physics are international, and do not depend on country where applied, and on how friendly are people who apply it.
Hello Wavebourn,
Of course, laws of physics are international.
I just don't understand what you are (trying to) point out because your English is poor. Please try again without coming up with formulas.
I prefer to calculate the primary AC resistance.
AC resistance is 2.pi.f.L, where f = frequency and L = inductance.
It is obvious that AC resistance varies with frequency.
Also L is not a constant, because it varies with frequency, signal level, and type of core material.
This means that primary AC resistance is a pretty rough figure.
I know how to specify primary "impedance" depending on load with the right amount of inductance!
Hey Stuart,
We are on a trip here. From Kansas via Dalhart TX to Albuquerque, Las Vegas,
California (Hey Wavebourn we even passed by Pleasant Hill). Right now we are in Colorado (visited John Broskie) on our way back to Kansas. Over 5000 miles in a 12 years old Ford Taurus towing a too heavy popup camper.
See you in France?
Pieter
Of course, laws of physics are international.
I just don't understand what you are (trying to) point out because your English is poor. Please try again without coming up with formulas.
I prefer to calculate the primary AC resistance.
AC resistance is 2.pi.f.L, where f = frequency and L = inductance.
It is obvious that AC resistance varies with frequency.
Also L is not a constant, because it varies with frequency, signal level, and type of core material.
This means that primary AC resistance is a pretty rough figure.
I know how to specify primary "impedance" depending on load with the right amount of inductance!
Hey Stuart,
We are on a trip here. From Kansas via Dalhart TX to Albuquerque, Las Vegas,
California (Hey Wavebourn we even passed by Pleasant Hill). Right now we are in Colorado (visited John Broskie) on our way back to Kansas. Over 5000 miles in a 12 years old Ford Taurus towing a too heavy popup camper.
See you in France?
Pieter
Please let me know what you can't understand in what I was "trying to point":
[off topic] Good luck in your trip! [/off topic]
Hi,
I checked Cinemag's website and their PDF of the transformer which is the subject of this discussion.
It is being specified as 1:5, so that is the winding ratio.
They also specify it as having an impedance ratio of 150 : 3750.
Of course this is the same 1:5 winding ratio, but their impedance spec suggests a primary inductance in the order of 1 Henry (there is no inductance spec), which is confusing
Then the PDF specifies the gain of the transformer with a secondary load of 39k2 and a source impedance of 150 ohm. In this case the 150 ohm source will see a reflected load of 1568 ohm (39200 divided by 5²) so that most of the 1:5 winding ratio is transformed into voltage gain. AT 20 Hz the 150 ohm load needs an AC resistance of the same 1568 ohms which calls for about 12 Henry of primary induction.
When the secondary load is 3750 ohm, the 150 ohm source will see a 150 ohm reflected load, an this load will kill the gain of the transformer, but bandwidth will be good.
I am not into microphones, but the situation is not directly comparable with a triode being the source. We want the triode to see a primary impedance of at least double its plate resistance, and often more, to minimize distortion.
It might very well possible that microphones do not necessarily need a higher load impedance to function properly; the load will be chosen higher however to get the voltage gain through the transformer.
Wavebourn, I don't understand what you mean with the secondary impedance being parallel to....primary load?
Pieter
Tribute Audio Transformers
I checked Cinemag's website and their PDF of the transformer which is the subject of this discussion.
It is being specified as 1:5, so that is the winding ratio.
They also specify it as having an impedance ratio of 150 : 3750.
Of course this is the same 1:5 winding ratio, but their impedance spec suggests a primary inductance in the order of 1 Henry (there is no inductance spec), which is confusing
Then the PDF specifies the gain of the transformer with a secondary load of 39k2 and a source impedance of 150 ohm. In this case the 150 ohm source will see a reflected load of 1568 ohm (39200 divided by 5²) so that most of the 1:5 winding ratio is transformed into voltage gain. AT 20 Hz the 150 ohm load needs an AC resistance of the same 1568 ohms which calls for about 12 Henry of primary induction.
When the secondary load is 3750 ohm, the 150 ohm source will see a 150 ohm reflected load, an this load will kill the gain of the transformer, but bandwidth will be good.
I am not into microphones, but the situation is not directly comparable with a triode being the source. We want the triode to see a primary impedance of at least double its plate resistance, and often more, to minimize distortion.
It might very well possible that microphones do not necessarily need a higher load impedance to function properly; the load will be chosen higher however to get the voltage gain through the transformer.
Wavebourn, I don't understand what you mean with the secondary impedance being parallel to....primary load?
Pieter
Tribute Audio Transformers
Hi Wavebourn,
Looking for specs of microphone step up transformers I finally arrived at the website of your beloved Edcor.
They sport a 1:5 microphone step up transformer with a 150 ohm or more "primary impedance", the MXL5.
For your interest: their spec of primary induction is 0.3 Henry.....
So it seems that my initial spec of 1 Henry is not far beyond of what is typical for this type of transformer??
Looking further I don't find inductance specs of Jensen, Lundahl and some other brands of microphone step up transformers.
Pieter
Tribute Audio Transformers
Looking for specs of microphone step up transformers I finally arrived at the website of your beloved Edcor.
They sport a 1:5 microphone step up transformer with a 150 ohm or more "primary impedance", the MXL5.
For your interest: their spec of primary induction is 0.3 Henry.....
So it seems that my initial spec of 1 Henry is not far beyond of what is typical for this type of transformer??
Looking further I don't find inductance specs of Jensen, Lundahl and some other brands of microphone step up transformers.
Pieter
Tribute Audio Transformers
Pieter, we're in Austin, TX, so it may be worth a swing by. Say hello to John for me.
No France this year for us, I'm afraid. Next year, if all goes well.
No France this year for us, I'm afraid. Next year, if all goes well.
Wow, my lil' question stirred up lot of discussion, good info in there, for me.
I did email Cinemag regarding inductance specs and they do not specify it at all, like Jensen, Lundhal...
Questions:
For a simulated model, I understand that the inductance of the primary coil is in parallel with the reflected impedance from the secondary coil, is that correct? Example, the 39.2k secondary load reflected as 1.568k is parallel to the primary Xl. My initial thought would have been in series, but I'm not the pro here!
What about the secondary coil's inductance? Is that also reflected into primary?
Thanks!
IG
I did email Cinemag regarding inductance specs and they do not specify it at all, like Jensen, Lundhal...
Questions:
For a simulated model, I understand that the inductance of the primary coil is in parallel with the reflected impedance from the secondary coil, is that correct? Example, the 39.2k secondary load reflected as 1.568k is parallel to the primary Xl. My initial thought would have been in series, but I'm not the pro here!
What about the secondary coil's inductance? Is that also reflected into primary?
Thanks!
IG
Check the equivalent circuit:
Transformer - Wikipedia, the free encyclopedia
The inductance you can measure on the primary is Xm. You can measure it with the secondary open circuit. It is parallel inductance.
The leakage inductance Xp and Xs are series inductances, you can measure them with shorted secondary.
Transformer - Wikipedia, the free encyclopedia
The inductance you can measure on the primary is Xm. You can measure it with the secondary open circuit. It is parallel inductance.
The leakage inductance Xp and Xs are series inductances, you can measure them with shorted secondary.
The secondary looks like the secondary inductance in series with the secondary resistance in series with the load. Then that gets reflected back to the primary by 1/n2.
Dear Pieter;
however, English is not my native language, but laws of physics are
international, and do not depend on country where applied, and on
how friendly are people who apply it.
Hi WB ,
Yes the laws of physics are the same everywhere but its how you apply them.
Posting those equations is an insult to idiot, if you cannot see that then ......
Quite frankly most of what your saying is not very understandable,
because I assume you see it in some way that is not "standard".
rgds, sreten.
TRANSFORMERS : Volume II - AC
"Hi,
Note that I said for both cases derated, I did not state the amount of deration.
rgds, /Sreten. "
Hi,
I didn't think Faraday's law was open to debate. Miles presents the correct formula, note that load current is not one of the terms. Saturation is a function of voltage and frequency. This can't be changed by reducing load current. (the core does have a max. current capacity, as does the wire, but that's not the same limit).
I'd like to see someone who doubts this actually try connecting a 110V isolation transformer to 220V and report the results back here. Please use a good fuse of the correct rating on the primary!
Cheers,
Michael
TRANSFORMERS : Volume II - AC
Hi,
The above has some SPICE circuit details.
So if the primary is 0.3H then the secondary must be 1.5H ?
I ocassionally use the free TinaTi SPICE :
SPICE-Based Analog Simulation Program - TINA-TI - TI Tool Folder
It has an easy AC analysis feature and a very nifty impedance meter feature,
allowing to to see the impedance at any point across the frequency range.
rgds, /sreten.
I think the secondary inductance is reflected in the primary as the square of the turn ratio, so by a factor of 25 in this case, not five.
IG
The CMMI-5 is meant to be used with a microphone having a source impedance of 150 ohms, loaded by a reflected impedance of 1600 ohms. Common condenser mics with active circuitry expect a load of 1600 ohms. This allows designing the first preamp gain stage with a low noise figure.
Their spec of -.08db at 20 Hz small signal with a 150 ohm source and 1600 ohms reflected impedance implies quite a lot of inductance, on the order of tens of henries.
As you say, inductance changes with frequency, so this method of specifying loss under given frequency, voltage, source, and load conditions allows proper selection without needing to know the exact inductance.
Cheers,
Michael
Hi,
Yes your right. To get the 1:5 turns ratio the two inductance
values you mutually couple in the SPICE simulation = 1:25.
Checking in Tina TI you specify the ratio N1 to N2 directly
with the mutual inductance, I'm not sure how you can
put in the actual inductance values.
rgds, Sreten.
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