Actually, I'd expect a transformer to roll off the bottom end. As you get closer to DC, the rate of change falls off and it won't transform. Higher frequencies do carry over. You've demonstrated that at the higher end, the choice is between ringing and roll-off.
You make my day better. Your genuine nature is so damn rare on RU-vid. Trying to hunt down ever bit of ring depends on how much noise vs signal attenuation matters. It’s engineers not science. People are flip-flopping around to get whatever answer they think they remember from school, reddit, whatever. Forget it. Your answers are as true for you today as they are everyday. You are the real deal. ••• and you don’t have that many years on me so •••
Great reprise. Since you are a radio guy, have you ever used a transformer in a studio mic line box like the w2hy isolation boxes. An isolation box build would make a great vid. May do one myself, but just curious. Thanks for the video
Distortion is caused by any non linearity. Transformer cores have two sources of non linearity. Hysteresis and core saturation. BH curves are non linear at the beginning of magnetisation and at the point approaching saturation. If you operate the transformer only between these in the linear section your signals will not suffer non linear changes, eg. Distortion.
Great video. Maybe the signal integrity at higher frequencies is not so great because you need to do impedance matching on the primary side of the transformer as well.
Assuming the same wire is being used on both windings, you get the ratio between windings equal to 180:120 = 3:2. That means the resistance you place on the secondary is seen from the primary as (3/2)² = 9/4 times larger or smaller depending on which way round the transformer is connected. In one case, you loaded the secondary with 6K8 and in the other case you needed a load of 2K2. Assuming you're only able to estimate the matching impedance to around ±20% or so, that's perfectly consistent with required loading of somewhere around 4K on the primary (4k x 9/4 = 9K and 4K x 4/9 = 1.8K).
Transformers also raise the lower frequency cutoff; they don't work at DC as an extreme limit. Also, the driver output impedance comes into play since tau=RC or tau=L/R. (Most precisely, superconductive windings do allow infinite time constant and DC response, but these are not superconductors.)
The vise can bridge the “air gap”, which could affect the magnetic characteristics of the core itself. The “air gap” is actually created by physically inserting some non-magnetic strips between the E and I shaped of the core. That transformer you used is not a C core; a C core will not have four sides of core visible as in this transformer; a C core only shows three sides visible.
@@IMSAIGuy it IS an E I core without a doubt. The only question is whether all E laminations are oriented in the same direction or not. I can’t tell from the video. It definitely is not a C core.
@Tiago Ferreira - thanks, I see that now where he flips it around. So no real air gap involved, and his statements that the vise has little effect would be correct.
Since a transformer does not pass DC current from input to output, the DC resistance isn’t impacting the response to AC signals as much as the AC impedance of the transformer and the other circuitry being used. And bandwidth is typically measured at the 3dB down level, meaning 1/2 power being delivered at either end of that frequency range being specified as the bandwidth.
The hand mike for my Kenwood TS-440SAT, constantly gets on air comments about the quality of my on air sound... the Mike circuit consists of a dynamic microphone hooked up to a transformer, which is then fed to the radio. It is very simple, but seems to work remarkably well!... and the ground, on both sides of the transformer are connected together! :)
Optionally if you want to extend this series - you could demo max power transfer matching. I assume the generator is 50ohms. How to load the transformer to get the max power transfer,...?
Capacitors added onto the transformer (which is in simple terms an inductor) can be used to tune things, even to the point of creating a resonant frequency. For audio purposes, the capacitor would be used along with a resistor so that the reactance is flatter across frequencies.
Yes and no. It would show in good, sensitive difference measurements. But it would not matter, because the saturation itself is huge distortion. In audio transformer you want to stay far away from a saturation. The ringing can be described as the effect of stray inductance and stray capacitance resonating. You want good coupling, or mutual inductance, while you want to minimize both stray components. Another concern is whether you are dealing with an amplifier output transformer or an input transformer like one from a microphone. The difference is that the output transformer distortion is normally compensated by a feedback brought to the amplifier from the transformer secondary side. On a microphone transformer there is no correcting feedback around the transformer.
Measuring/categorizing transformers using DC resistance isn't really the best way, as wire gauge comes into play. In this case, with a simple audio transformer it is ok, though. But measuring the inductance is a much better way to easily categorize the primary/secondary winding ratios. If you have an LCR meter, it wouldn't be any more difficult than using the multimeter to measure the DC resistance.
Are we talking about output transformers or input (like microphone) transformers? On most output transformers you take feedback to the amplifier from the secondary of the transformer. Thereby you attenuate any distortion by the amount of the feedback, maybe 20 dB which equals 1/10 in voltage. You generally never have that available on microphone transformers. As to the measurements - it would have been much better to use two channels of the scope, one on primary and the other on secondary to demonstrate the potential differences caused by the transformer.
That is the second time I see that in your video about this series is how you wire the transformer itself on the primary and secondary and you never mentioned anything about it. To me it looks like you are wiring your generator on one side on the secondary and secondary and you do the same with the scope... Have I wrongly wired audio transformers in all my projects or it is the way yours is designed?
Really?... Uh... So the source should be wired to one pin on the primary and one pin on the secondary ? I'm here to learn and I can say I learned something i clearly do not understand !
@@IMSAIGuy yes that is what I meant, to me it looks like your transformer is connected sideways, that is what I meant and I did not understand how you could connect it that way and that is was working !
Hmm? I ponder! this is why TI makes specialty audio amps/chokes\transformers... U may have been bitt'n by a Decepticon!! Transformers! isn't it great 2 be part of a community!
