Will the issues raised signal generator can not be used in a multi-ring track it? Causing inductor ring track 160 microhenries inductance, resistance 8.7 ohms. 94 m, cross road and rings, annular structure 9, the inductance value is relatively large.
Lang Lang's universe, a lengthy track
But my signal generator has been jumping from 0 to move to 50-96, this cycle has been beating. Or not, it is now between 100 and these three numbers 1088 beating.
Display signal generator fluctuates
A basic principle, the source maximum load impedance "
"Push officially recommended paper discusses the equivalent circuit of the output stage of the transmitter signal. In the case where the external load is equivalent to an inductor in series with a resistor, the output voltage waveform should be a square wave pulse signal. Since the internal control signal constant current source , so when larger external reactor, the greater the pulse duty cycle. when the output is 50% of the square wave signal, corresponding to the maximum output voltage signal.
The maximum voltage of the signal generator output 50% duty cycle square wave signal
The output of the bridge circuit in the form of a complementary MOS assumed working voltage U = 7.5V, MOS state voltage drop is ignored, the peak value of the output square wave: U * 2 = 15V.
Symmetric Wavelet components calculating the present
Decomposition by Fourier series, we can calculate the effective value of the fundamental signal U1 output signal square wave voltage = 6.75V. Corresponding to a peak current of 100mA square wave, corresponding to the effective value of the fundamental current I1 = 90.03mA. It can be calculated, the maximum load current does not exceed the signal generator is an anti-U1 / I1 = 75 ohms.
Second, the principle of the signal generator steady flow of new digital signal generator, using current fundamental principle of feedback to ensure a fundamental wave of the output current is kept constant. In particular the principle of "
"Had been introduced by signal generator control software found no fundamental output current reaches the set value, the output voltage will increase until the final due to an external impedance is too large, or open, causing the output current never been able to achieve fundamental the set value, then the signal generator will start again from zero and gradually increase the output current value. Therefore, the signal generator show fluctuation occurs only open in the external impedance is too large or when it occurred.
Signal generator internal circuit boards
None **** explain the problem display signal generator display fluctuations, should be the signal generator can not be guaranteed 100mA output current set for the beginning of the problem. In this case the corresponding external electromagnetic coil impedance exceeds 75 ohms. However, given the foregoing electromagnetic coil ohmic resistance R = 8.7; L = 160 microhenries. At this time, the corresponding inductance 2 = X- PI F L = 20.11 ohms. The overall reactance = sqrt the Z (R & lt R & lt * X-X-+) = 21.9 ohms. This impedance is far less than the maximum load the signal source. Therefore, the possibility of this problem is the failure of the signal source. None
Old Signal generator output voltage and the relationship between the external inductor
None In summary, you can get a preliminary guess the conclusion is that the signal generator is still questioning the students used an older version of an electromagnetic signal generator. Its external load capacity can not meet the requirements of the track impedance now.
Solution: Replace the signal generator software, so the output current feedback to achieve real fundamental component of the past and avoid errors legacy signal generator.
The results :
Experiment 1: a feedback signal generator to make the fundamental wave signal generator comparative experiment using a new version of the fundamental wave feedback, driven by an inductor and a wear resistance of 12 ohms 330uH together, using the power supply of 7.5V. The results: you can see the display is stable.
Experiment 2: increase the inductance of Complex using two 330uH inductor in series, inductance L = 660uH, then the new version of the signal generator. It found that the new version of the digital generator display appears fluctuation.
In this case, the external reactance = 2 X- PI F L * = 82.9 ohms, work beyond the maximum external signal source impedance values at 7.5V (75 ohms), the display signal generator occur fluctuations.
The solution is to increase the operating voltage of the signal source. For example, up to 9V, the upper limit of the load at this time corresponds to 90 ohms.
Extended summary This paper analyzes the maximum external load capacity of the signal generator. In the case where the power supply is 7.5V, the maximum output load is 75 ohms. When the external load is greater than the reactance of 75 ohms, the signal source fluctuations occur in the internal mechanism of the steady flow.
Analysis process needs to be applied to the Fourier series decomposition formulas, one important conclusion is that for a given symmetrical square wave signal, if its peak E, it is the fundamental wave signal 2E / pi.
For the LR series with the load, its reactance is equal to the value of the square and the square root of the resistance and inductance. It is equal to the inductive reactance X 2 PI F * L. Thus, after the completion of the laying of the track, the track needs to be pure resistance and inductance were measured, ultimately calculate the total reactance values at 20kHz magnet wire. The maximum load value is less than the required signal, otherwise the signal generator outputs the periodic fluctuation occurs.
If the maximum load everyone in the hands of the new signal generator can not achieve 75 ohms, you need to consider replacing the control software of the signal generator.
