How to separate the sine and cosine signals of the same frequency? In some special occasions in the audio system, small current and high voltage are required...

dongyaobin

maychang

The original poster raised two questions. The first one is "In some special occasions in the audio system, a low current and high voltage audio signal is required, but the audio signal voltage output by the power amplifier is generally only a few volts to tens of volts. What should be done if the required audio signal voltage reaches several thousand volts?" The second one is "The transformer output signal contains two sine and cosine signals of the same frequency, which interfere with each other. How to separate them?"

maychang

The first problem: Audio signal voltage reaches several thousand volts. It can be done, but it is quite difficult. The main reason is that the withstand voltage of ordinary MOS tubes is only about one thousand volts, and multiple high-voltage MOS tubes must be connected in series. The difficulty lies in the average distribution of voltage between the series tubes.

maychang

The second question: a sine signal and a cosine signal of the same frequency (regardless of amplitude) are two sine signals with the same frequency but different phases. When two signals with different phases but the same frequency are added together, they are still a sine signal with the same frequency and different phases from the two signals. Therefore, the "two sine and cosine signals of the same frequency in the transformer output signal" cannot be separated.

maychang

The article mentioned that "an audio transformer is now made to amplify the voltage, and its principle is shown in the figure", and also mentioned that "the acceleration of wire ab..." I can only say: I don't understand what it means.

maychang

"Is the transformer designed in this way correct in principle? If not, what is wrong with it?" It is wrong in principle. Transformers work by changing magnetic flux, not by moving wires.

dongyaobin

maychang posted on 2018-7-7 17:43 "One: Is the transformer designed in this way correct in principle? If not, what is wrong?" It is wrong in principle. The transformer relies on...

Hello, this voltage amplification method is different from the usual transformer that works on the principle of mutual inductance. What I mean is whether the principle of this transformer is correct, not whether it is the same as the usual transformer principle.

captzs

As M said, the same frequency sine and cosine waves are combined into a sine wave. The so-called "separation" by the original poster is actually to decompose a sine wave into two sine waves with a phase difference of 90 degrees. The two-order cutoff frequency circuit can shift the phase by 90 degrees, and if there is an amplitude requirement, it can be amplified.

dongyaobin

[quote]maychang posted on 2018-7-7 17:29 The original poster raised two questions. The first one is "In the audio system, some special occasions require small current and high voltage audio signals, but the audio signal voltage output by the power amplifier is generally only a few volts to tens of volts. What should be done if the required audio signal voltage reaches several thousand volts?" This is the description in the material. Not to mention what this question wants to ask, there are indeed two questions asked in this post: Question 1: Is the transformer principle described in the material correct? Question 2: If it is correct, the transformer output signal contains two sine and cosine signals of the same frequency, which interfere with each other. How to separate them? Thank you

maychang

dongyaobin posted on 2018-7-7 18:13 Hello, this voltage amplification method is different from the usual transformer that works on the principle of mutual inductance. What I mean is whether this transformer principle...

Your design (I don't call it a transformer to avoid confusion) is correct in principle, but the efficiency is estimated to be very low. I wonder if you understand the structure of a dynamic speaker? If you do, then your design is to remove the two dynamic speaker cones and glue the two voice coils together. If you don't understand the structure of a dynamic speaker, you can also use an electric motor driving a generator as an analogy, except that the electric motor and the generator do not rotate continuously but swing.

maychang

dongyaobin posted on 2018-7-7 18:17 In some special occasions in the audio system, low current and high voltage audio signals are required, but the audio signal voltage output by the power amplifier is generally only a few volts to tens of volts...

Question 1: Is the transformer principle described in the material correct? The 10th floor has been answered. Question 2: If it is correct, the transformer output signal contains two sine and cosine signals of the same frequency, which interfere with each other. How to separate them? There is no "mutual interference". If a certain sine signal must be divided into two signals with a phase difference of 90 degrees, see the reply of captzs on the 8th floor.

maychang

dongyaobin posted on 2018-7-7 18:17 In some special occasions of the sound system, low current and high voltage audio signals are required, but the audio signal voltage output by the power amplifier is generally only a few volts to tens of volts...

The reason why your design is not called a transformer is that the first step of your design is to convert electrical energy into mechanical energy (the ab segment wire drives the "insulation frame"), and the second step is to convert the mechanical energy of the "insulation frame" movement into electrical energy. Because of this, I said "the motor drives the generator" on the 10th floor.

dongyaobin

maychang posted on 2018-7-7 18:42 Your design (I will not call it a transformer to avoid confusion) is correct in principle, but the efficiency is estimated to be very low. I don’t know if you understand the dynamic type...

You are right. In principle, it can be equivalent to two voice coils of a dynamic speaker glued together. The key is that it can be amplified in principle and no errors can be found, but the experimental detection structure is inconsistent with the theoretical reasoning. It is detected that the output signal voltage of the CD stick is very low, and the signal voltage after two derivations has not been measured. I estimate that the two parts of the signal exist simultaneously in the time domain and superimpose on each other, which finally makes the measured signal voltage very low. That is why it is required to separate the two parts of the signal.

dongyaobin

captzs posted on 2018-7-7 18:15 As M said, the same frequency sine and cosine waves are combined into a sine wave. The so-called "separation" by the OP is actually to decompose a sine wave into two phases...

Two-order cutoff frequency circuit? Can you explain it in detail?

captzs

According to the definition, when a sine wave is transmitted in a circuit at its cutoff frequency, the first order phase shift is 45 degrees, and the second order phase shift is 90 degrees. This is the same for any sine wave. Therefore, it is impossible to "separate" two sine waves of the same frequency with different phases. This is a difficult problem in the communication industry.

maychang

dongyaobin posted on 2018-7-7 22:22 You are right. In principle, it can be equivalent to two voice coils of a dynamic speaker glued together. The key is that it can be amplified in principle and there is no error. ...

I said on the 10th floor: "Your design (I don't call it a transformer to avoid confusion) is correct in principle, but the efficiency is estimated to be very low." The low efficiency is because the electrical energy is converted into mechanical energy, and the mechanical energy is converted into electrical energy. The loss is too great when the two conversions are performed.

maychang

dongyaobin posted on 2018-7-7 22:22 You are right. In principle, it can be equivalent to two voice coils of a dynamic speaker glued together. The key is that it can be amplified in principle, and there is no error. ...

Return to the first post. "In some special occasions in the audio system, low current and high voltage audio signals are required, but the audio signal voltage output by the power amplifier is generally only a few volts to tens of volts. What should be done if the required audio signal voltage reaches several thousand volts?" If the bandwidth requirement is not very high, it is recommended to use ordinary silicon steel sheet core transformers, but the winding method of each winding is very particular. The ordinary winding method (similar to the winding method of the power frequency transformer) can achieve dozens of times the relative bandwidth (the ratio of the high-end frequency to the low-end frequency of the passband), and it will not work if it is wider. Special winding methods can be hundreds of times wider. If a wide range of 20Hz to 20kHz is required, the transformer cannot do it.

bigbat

You can refer to the design of the plasma speaker, which is an "air core transformer" Tesla coil. The voltage can be very high to form a plasma discharge.

bigbat

For the second question, we can use two high-frequency pulse samplings with a 90° difference between each other, split the signal into two paths and input them into the high-frequency sampling channels respectively, and cross-correlate the signals. In this way, the signals can be separated, but the signal phase and frequency must be relatively stable.

dongyaobin

maychang published on 2018-7-8 08:27 Return to the first post. "In the audio system, some special occasions require low current and high voltage audio signals, but the audio signal voltage output by the power amplifier is generally only...

It is because the material and process requirements of the transformer are too high to ensure linear amplification of the signal in the entire audio range, and the volume is too large. Since the winding method is too particular, it can only be operated manually, which has limited mass production and high cost, so we have to think of other ways. According to the method described in the attachment, it can be amplified in theory, but the actual measurement results are inconsistent with the theory. I don’t know whether it is due to imperfect experimental conditions or problems in theoretical derivation.