Questions tagged [coupling]

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Mutual inductance and coupling coefficient

I need to know how I calculate the coupling coefficient and mutual inductance in series-parallel (SP) topology in wireless power transfer system work at a resonant frequency of 6.78 Mhz
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47 views

Can someone explain the dependence of coupling coefficient to inductance value to me? It seems counter intuitive

According to the formula \$K=M/\sqrt{L_1 L_2}\$, it seems that k is inversely proportional to the inductance values of the two coils. However, it seems to me that a coupling between two 2uH inductor ...
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19 views

How do terminate the coax shield of AC coupled LVDS signal? (isolated grounds)

I have an LVDS clock signal that goes to several PCB cards. Frequency: 100Hz --> 20MHz I am going to use a fan out IC to supply each card with it's own buffered CLK signal; I am not going do a '...
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52 views

How to pass a signal over isolator with only one side powered?

I have a system composed of a 230VAC zone isolated from a human contact zone with a 7.5mm 2k5 space. On the human side there is a dry contact switch: I am searching for a less than 1€ solution to ...
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41 views

Coupled inductors formula

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab According to the dot notation rule the current :The convention is that current entering a transformer at ...
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54 views

How to determine which type of coupling is this?

A new model sports car had a disconcerting problem: occasionally the dashboard lights would all illuminate simultaneously. Two services call later, replacement of a wire harness for the spark plugs ...
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1answer
56 views

Op-amp offset voltage and capacitive coupling

About the circuit above, I can't understand from the row "VA=2Vos". If that's because most of the voltage between 1K ohm resistor and capacitor is on 1K ohm then I can't understand why VA ...
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2answers
45 views

Best way to connect coax along a microstrip

I have an open-ended (stripped, if needed) coaxial cable that I would like to use to insert a signal into a microstrip. The circuit (operating at ca. 18 GHz) however, is made in a way where I can't ...
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41 views

PLC (Power Line Communication) data line coupling to speakers

I have a PLC (Power Line Communication) to provide internet thorugh cable to all rooms. The problem I have is that this internet data is coupled to the speakers. I can hear like a "noise" (...
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1answer
57 views

Unkown DC offset of an isolation amplifier circuit design

I am designing an isolation amplifier that consists of the following blocks: A comparator which produces a PWM signal A coupling capacitor that achieves galvanic isolation A voltage follower that ...
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11 views

Coupled current in shield in a tube from a transient surge

If a shielded cable (B) is running inside the centre of a tubular structure (A), how is the coupled current from a surge estimated in the shield? I am trying to figure out how the coupled current ...
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39 views

Regarding Magnetic coupled circuit

Here, all the initial conditions are : i1(0-)=0A and i2(0-)=0A When t≥0, the current i1(t) and i2(t) starts flowing. From my assumption, steady state value of i1(t) is 10A but what happens to i2(t)? ...
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45 views

Output AC coupling: upper limit or lower limit?

I bought a DC2900A board for my project. In its datasheet it is stated: The maximum repetition rate of the pulsed laser should be 100kHz. The DC2900A repetition rate is limited by the output AC ...
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59 views

Why are the coupling capacitors needed in this DCM converter?

I have a 48V power supply which needs to be converted to a 12V output. I want to achieve this by using the DCM2322 dc/dc converter. In the Datasheet the following recommended circuit is given: My ...
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1answer
56 views

Understanding of coupling coefficient and power transfer efficiency

I am a bit confused about my derivation to get power efficiency from the coupling coefficient. The coupling coefficient \$k=M/\sqrt{L_1L_2}\$. $$ V_2=M\frac{dI_1}{dt}=L_2\frac{dI_2}{dt}\\ V_1=M\frac{...
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1answer
94 views

Location of AC coupling capacitors

I am trying to decide location of AC coupling capacitors between FPGA and PHY SGMII interface and datasheets of neither part has any useful information. I've read some notes, like this one from Dr. ...
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2answers
54 views

Oscilloscope probe coupling [duplicate]

I am using this buck converter. Schematic: Buck Converter Specifications : Input Voltage - 18V to 32V Switching Frequency - 300kHz Output Voltage 9V Load Current - 0mA to 200mA Maximum. When ...
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277 views

Roles of the coupling and bypass capacitors in a CE transistor

I wonder what the purpose of the coupling capacitors and the bypass capacitors are and the type of effect each capacitor has on the circuit. As I've understood it, you use coupling capacitors to block ...
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2answers
46 views

What is the right way to measure K on an inductor with three coils?

I have an inductor which has three coils, L1, L2, L3. In normal use L2 and L3 are connected in series, and resonated with a capacitor. L1 would then drive the tank circuit. In Spice, I need the ...
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1answer
58 views

How is this LCD controlled?

Source: https://ozhealth.com.sg/product/genial-digital-thermometer-t15-orange/ I tore down a digital thermometer today (a Genial T15), and the interface to the LCD caught my eye: although there were ...
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1answer
74 views

Why isn't capacitive coupling considered in EMC testing?

It seems like the emissions of interest in EMC testing are radiated and conducted emissions. Is this because capacitive coupling is so weak it doesn't pose a threat to other devices?
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3answers
178 views

DC-DC converter isolation capacitance return path?

For those isolated DC-DC converter bricks like seen in the photo below: The data sheet specifies an isolation capacitance in the order of picofarads. And in order to meet EMC requirements they ...
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1answer
80 views

Find the Q-factor for coils and understand weak power transfer

I built coils for wireless power transfer. Found inductance with a LRC meter. Put capacitors, hoping for a resonant frequency at 300kHz. Student assisted me with a NVA machine where a resonant ...
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21 views

“Coupling” gain-setting resistors in a single-ended source, differential amplifier?

I am working on a fully differential amplifier design that receives a single-ended differential voltage from a piezo sensor. I computed a theoretical gain and selected appropriate resistors and it ...
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26 views

Ac current injecton to dc bus

I want to inject a 2V ac sine wave on a 480V dc bus. to protect my ac signal generator from entering high dc voltage I am going to use capacitor as coupling device. Ac generator also should deliver 15 ...
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2answers
73 views

AC coupling of a transistor

So we assume to have proper bias currents flowing in both of the two transistors. What is claimed by books is that a capacitive coupling will not change the bias parameters. But, we know that a ...
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294 views

Royer oscillator - frequency shifting in WPT

I am having a problem with my WPT resonant application. In my circuit modified Royer oscillator feeds LC tank. Receiver coil nearby is connected to rectifier and variable resistor. I know about ...
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2answers
102 views

EMC - conducted emissions - unused wires in cable - puzzling coupling

I am trying to understand the impact of unconnected wires in a cable for EMC conducted emissions tests. My product has a shared unshielded cable for supply and communication (I know it's bad practice....
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87 views

Where is the capacitive coupling in this adafruit soil moisture sensor?

Here is the moisture sensor: https://learn.adafruit.com/adafruit-stemma-soil-sensor-i2c-capacitive-moisture-sensor/downloads It has a large copper area insulated with soldermask that sticks in the ...
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65 views

Understanding Ac coupling in this circuit

I'm simulating the circuit below in LTspice and there's something I don't get regarding C3 and C4. Suppose the input signal is a 32 uArms 60Hz current as shown. This value multiplied by the burden ...
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97 views

How to measure capacitive coupling on pcb traces?

I have bare PCB board (6 layers) with me and I would like to see if my switching signals (60 kHz) have any effect on the sensitive current measurement lines. I just want to know if there is quick ...
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1answer
152 views

How to calculate cutoff frequency for a high pass filter in DC biasing circuit

I would like to DC bias an AC signal using a voltage divider as shown in the following schematic. I realise the bias point would be subject to noise from the power rails, but that is not a concern for ...
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1answer
98 views

Coupling coefficient of microstrip resonators

I am working in HFSS and I'm trying to determine the coupling coefficient between two microstrip resonators (k) so that I can design a filter using a certain resonator shape. I have the formula I need....
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2answers
173 views

Unintentional capacitive coupling

This question comes from text from the AOE 3rd ed. It's about unintentional capacitive coupling right after differentiators in chapter 1. I've included the text. Please read the first excerpt. That is ...
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1answer
27 views

Does DiSEqC require a DC bias?

The DiSEqC (Di[gital] S[attelite] Eq[uipment] C[ontrol] specification (bus_spec.pdf within https://www.eutelsat.com/files/PDF/DiSEqC-documentation.zip) describes a tone-based serial data bus that can ...
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3answers
145 views

Shifting level voltage of a signal

I have a signal, which can vary from 400 to 7000 Hz approximately. It is a kind of pwm signal and has the time of high level, Ton, 30 times longer than the time of low level, Toff. The shape of the ...
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3answers
197 views

Adding small AC signal to a DC current using inductive coupling

Is it possible to add a small AC current on to a DC current in a wire using inductive coupling from an external source. Or if there is another way, I want to add AC ripples to a DC current. simulate ...
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1answer
86 views

What grounding should I use for this capacitively coupled input?

I'm designing a device that will receive and digitize analog video signals. In analog video, it's recommended to capacitively couple inputs. A typical input might look like this: In this case the ...
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1answer
130 views

2n7000 used for inductively coupled load modulation apparently latched

So I've got a fairly basic circuit set up for load modulation of an inductively coupled circuit: A few notes on the above: LC's were designed for 1 MHz but work better at 950 kHz, thus the chosen ...
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4answers
546 views

AC-Coupling on Composite video

Many sources say that composite video input should be AC-coupled. Voltage levels for blank, black and white signal are also specified. How is it possible to detect these voltage levels after AC ...
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3answers
133 views

If a PEC surface completely reflects an EM wave, why doesn't an ungrounded shield work?

I was thinking about shielding and its effectiveness. An ungrounded shield doesn't work well for either inductive or capacitive coupling. However, if you think about plane wave theory, a PEC surface ...
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1answer
355 views

Coupling PCB traces

In my pcb design I have 2 triangular voltage signals with the following specs: Peak voltage = 300V Rise and fall time= 7us Freq=25kHz (assume a constant current of 0.5A) Because of the limited ...
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1answer
130 views

Could shielding (not grounded) affect signal integrity?

I'm trying to shield 6 flat cables that give me some communication issues because I thought that there might be cross-talk or other sources of interference that cause the problem. The shielding is ...
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2answers
812 views

How does placing cap between signal GND and earth GND solve common mode noise?

Thanks in advance for your time. I am reading several articles about differential mode noise and common mode noise. Among which I found the below 2 pretty instructive: https://www.murata.com/~/media/...
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60 views

Maximum ringing due to inductive coupling

Consider a bundle of wires carrying binary data and the worst case (or almost-worst case) scenario of them switching all at the same time. The wires with their partial mutual inductances would be ...
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2answers
549 views

Parallel inductive coupling approximation - coupling coefficient

I have the problem of a few independent current loops (wires) that on a portion of the circuit are close to one another so there will be inductive coupling between them. Each wire, on the portion of ...
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1answer
175 views

Crosstalk between AC and DC

First time asking a question but I've come across something I just can't find the answer to. Whether or not it's because a silly question I hope to find out. So I understand that with crosstalk ...
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3answers
460 views

How do I terminate a directional coupler?

I'm using a directional coupler for a radar application using frequencies of 5.3-5.9GHz. The directional coupler linked above is matched to a 50ohm characteristic impedance. How do I terminate the ...
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149 views

Coupling coefficient variation in Wireless power transfer

Question regarding WPT compensation topologies. I'm trying to make a inductive wireless power transfer system where the RX coil can move quite conisderably relative to TX coil and still transfer ...
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3answers
245 views

Why does the voltage induced in the receiver coil of this WPT circuit decrease when a load is added (in parallel)?

The following is a circuit that wirelessly transfers power via inductive coupling. The circuit is supposed to power a 12 V 0.15 A DC fan and a typical smartphone, which requires 5 V DC across it. The ...