Activity for TonyStewart
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A: Minimizing Common Mode Radiation - Separating Grounds The problem with cable emissions from HS data and SMPS noise is very common even with UTP and ribbon cable with adjacent grounds on differential signals. I have seen this frequently on HDD testing at EMC sites, whereas the HDD emits nothing of interest. The problem is due to the imbalance of the... (more) |
— | over 1 year ago |
| Comment | Post #286900 |
If I understand what you said refers to my description of a differential amp (DA) with 3 NPN's , " There is a negative feedback in this common-base (CB) stage driven by an input current " then I cannot agree.
The emitters are "common" to input and output so it is not a CB but rather differenti... (more) |
— | over 1 year ago |
| Comment | Post #287265 |
You would need a spectrum analyzer to determine the signal from line noise due to SMPS , motor starts and Triac dimmers in order to determine the Noise rejection required. But yes you should expect interference with the wider -40 and -60dB BW unless it was at least 6 to 8th order. (more) |
— | over 1 year ago |
| Comment | Post #287257 |
It seems you still use the single-ended topology but integrate current offset error with Hall, Rs or dual CT sensors to correct for the asymmetric current in each supply. (more) |
— | over 1 year ago |
| Edit | Post #287265 |
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— | over 1 year ago |
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— | over 1 year ago |
| Edit | Post #287265 |
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| Edit | Post #287265 | Initial revision | — | over 1 year ago |
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A: Ceramic filter vs ceramic resonator A resonator cannot replace a filter because the filter has multiple resonances to extend the bandwidth. For AM carrier modulation using a narrow band resonator with 0.5% tolerance of 6MHz or +/-30 kHz with a Q of 10k and its narrow -3dB BW can be as high as a crystal resonator but > 100 worse tol... (more) |
— | over 1 year ago |
| Comment | Post #286900 |
The simple ideas behind the differential amplifier are to ;
- eliminate the Vbe diode voltage offset from the input and choose any reference voltage for 0 output.
- use Ie to modulate gain when required
- choose either output for inverting or non-inverting gain or use both. (more) |
— | over 1 year ago |
| Comment | Post #287257 |
Does that mean you want it direct coupled but behave like a transformer AC coupled? Then the PFM or PWM drivers must have error feedback for the integral sum of current sensed from each to null the DC current and voltage feedback to null the error from the input voltage. So the answer lies in the ... (more) |
— | over 1 year ago |
| Edit | Post #287244 |
Post edited: so what |
— | over 1 year ago |
| Edit | Post #287244 |
Post edited: plot |
— | over 1 year ago |
| Edit | Post #287244 | Initial revision | — | over 1 year ago |
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A: Low-pass filter after the output DAC in CD players The oversampling is said to simplify the LPF yet the better reason is that it improves the SNR. Lower noise comes from better image rejection, lower filter ringing, and significantly lower group delay distortion in the audio band as the band edge is moved up. The majority of phase shift trav... (more) |
— | over 1 year ago |
| Comment | Post #285107 |
>Why does the collector current depend linearly on the base current?
When emitter resistance to supply rail is much greater than the base-emitter resistance re=26/Ie [mA] the voltage applied to the base is conducted to the base with Vbe drop. Thus there must be some relatively constant current g... (more) |
— | over 1 year ago |
| Edit | Post #287072 |
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— | over 1 year ago |
| Edit | Post #287072 | Initial revision | — | over 1 year ago |
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A: pH Electrode Buffer - Offset when solution grounded DC offsets in hundreds of mV from different grounds may be coming from either the floating ground or the PE earth. The latter may be from rectified AC line filter noise shunted to PE. The former might be caused by front-end ESD protection diode rectification with DC bias and a CM signal large enough... (more) |
— | over 1 year ago |
| Comment | Post #287027 |
Conductance = S=siemens
(Volume) Conductivity, σ is "siemens per metre" (S/m) is the length/surface area
Resistivity (rho) = "ohm-metre" = area/ length (more) |
— | over 1 year ago |
| Comment | Post #286900 |
"Common" refers to input and output references that are shared. Vce and Vbe depend on the external resistors. While "e" is common to both.
(more) |
— | over 1 year ago |
| Comment | Post #286900 |
The differential BJT amplifier is well-defined in simpler terms.
Av=Rc/(re+Re)=Rc/(26/Ie+Re) (more) |
— | over 1 year ago |
| Comment | Post #285107 |
We know Ic is precisely controlled by the exponential function of Vbe and current gain is very inaccurate. This means every device has a wide range of Ic/Ib in the linear range and exceptionally wide variation in the nonlinear range down to 10% of the maximum current gain at Vce=Vce(sat) or usually r... (more) |
— | over 1 year ago |
| Comment | Post #286900 |
The common terminal is not the least important, perhaps it is often ignored how important it is. (more) |
— | over 1 year ago |
| Comment | Post #281971 |
I expect your measurements are accurate enough, but now you realize how reflections within 10 wavelengths or so can affect your results. (more) |
— | over 1 year ago |
| Edit | Post #287007 |
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— | over 1 year ago |
| Edit | Post #287007 | Initial revision | — | over 1 year ago |
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A: Can confusing the plugs for earphones and microphones do any damage? If you mean electret microphone, no damage to JFET buffer. Microphone input won't damage a headset with it's current limited pullup resistor for electret Mics. (more) |
— | over 1 year ago |
| Comment | Post #286950 |
A bipolar switch rated for high Vceo seems to be all you need to protect the driver. Either high side PNP or low side NPN. >100V is easy to find. Your 1st plot is not to scale. (more) |
— | over 1 year ago |
| Comment | Post #286944 |
The ideal conditions are almost never achieved in ordinary ground communications, due to obstructions, reflections from buildings, and most importantly reflections from the ground out of phase. This fading can cancel up to all of the signal. So it is more important you define the path and all refle... (more) |
— | over 1 year ago |
| Comment | Post #286215 |
"across it" or it's own voltage is merely a value indicating the state of charge at some time. The actual charge Q = CV(t) for the capacitor's voltage. Your question is just about the semantics of a single test point (with an assumed common test point of 0V) or differential "across"
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— | over 1 year ago |
| Comment | Post #281971 |
What have you learnt? (more) |
— | over 1 year ago |
| Edit | Post #282053 |
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— | over 1 year ago |
| Comment | Post #286868 |
interesting analysis +1, close enuf for gov't work. (more) |
— | over 1 year ago |
| Edit | Post #282053 |
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— | over 1 year ago |
| Edit | Post #286867 |
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— | over 1 year ago |
| Edit | Post #286867 | Initial revision | — | over 1 year ago |
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A: Design high -pass filter with 2 points of the bode plot Filter design 101 - 1. given hypothetical high-pass (HPF) filter -3dB gain HPF at fc 2. attenuation of -8dB at fc/2 3. Assumptions gain = 0 dB at f>> fc 4. Ripple between -3dB and 0 dB is unknown but assume 0dB max for simpler case. 5. steepness of skirts << fc is unknown but we know 1s... (more) |
— | over 1 year ago |
| Edit | Post #282053 |
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— | over 1 year ago |
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— | over 1 year ago |
| Comment | Post #282053 |
@#8176 The reality is your results of variations are real and certainly affected up to 10 or more wavelengths from reflections.
The other reality is s21 is also affected by these reflections with multipath, so the net effect is to measure RSSI where possible in your receiver and test the variation... (more) |
— | over 1 year ago |
| Comment | Post #286211 |
Anti-aliasing filters are always needed when the spectrum above the Nyquist rate fs/2 will degrade SNR with the resulting difference frequency output. Thus dynamic range and spectral values ought to be estimated with desired SNR.
Typically a sampling rate might be 3x the upper frequency is the sp... (more) |
— | over 1 year ago |
| Comment | Post #286215 |
**Is this interesting?**
All voltages are relative to some reference. The local ground is defined as zero volts, just like Protective Earth PE ground. So if one side of the cap. is 0V then the voltage drop is the same as "the voltage" (relative to 0V.)
**What is reactance, really?**
It is ... (more) |
— | over 1 year ago |
| Edit | Post #286866 |
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— | over 1 year ago |
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— | over 1 year ago |
| Edit | Post #286866 | Initial revision | — | over 1 year ago |
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A: Circuit which create ac sine wave from dc pulsed signal This is about as simple an analog inverter that I can simulate, but warning, not for the beginner with resonance issues. The bridge diodes are 2f multipliers reduced to logic level with divide by 2 FF, then complementary inversion switches with a center tapped transformer with the tap having the i... (more) |
— | over 1 year ago |
| Edit | Post #286862 |
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— | over 1 year ago |
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— | over 1 year ago |