# Questions tagged [coupling]

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### Coupling/decoupling power supplies: how?

I'm adding a hi-Z adapter to a solid-state amplifier that is powered from the mains through a transformer and regulator. The hi-Z adapter is powered by 24 volts DC, so i need an external power supply ...
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### What is the role for each of these AC coupling components?

I'd like to learn more about the RP2040 PWM Audio AC coupling circuit found in figure 22 in this document. Figure 22. Schematic section showing the Analogue PWM audio circuit Even though I understand ...
• 101
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### Coupling LNA and Band-Pass Filter Properly

I am planning to use the BPF-A127+ band-pass filter with the GALI-74+ low-noise amplifier, which are from Mini-Circuits. The datasheets are provided below: BPF-A127+ Datasheet GALI-74+ Datasheet There ...
• 111
44 views

### Transmision and coupling coefficient in waveguide and ring resonator

A simple ring resonator with a bus waveguide is described by: \begin{pmatrix} B \\ C \end{pmatrix} = \begin{pmatrix} t & \kappa \\ -\kappa^* & t^* \end{pmatrix} \begin{pmatrix}...
• 145
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### How to capacitively couple an emitter follower to a load without losing most power?

As an exercise, I'm designing a circuit that takes a 7 MHz input signal (1V amplitude) with a source impedance of 1K and uses it to power a 50 ohm load. I used an emitter follower, and it works well ...
• 1,135
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### AC-JTAG Capacitor Value for differential signal testing

How to compute the value of AC-coupling capacitor to be used in AC-JTAG for testing high-speed differential signal? Can anyone give a more detailed insights on the proper consideration when ...
289 views

### RC coupling or LC coupling

I would like to generate a signal composed of an AC waveform and DC voltage separately, with the AC frequency range being 20 Hz to 20 kHz. I found there are two ways to achieve it: RC coupling and LC ...
• 141
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### Effect of coupling factor in flyback converter relative to rectifying diode

I'm simulating a CCM flyback converter on ltspice, and I need some help in understanding the results when I decreased the coupling factor from 1 to 0.96. When K=1, the voltage appearing across the ...
75 views

### Optimizing AC capacitor coupling for enhanced DC filtering

I need assistance in refining my AC capacitor coupling circuit to effectively filter the DC component of my input signal. The circuit consists of a current generator, a 1 Ω resistor, and an AC ...
1 vote
150 views

### Forms of Magnetic Noise Coupling

I was watching a video of Bob Pease discuss magnetic coupling of noise into the ground lead of an oscilloscope probe. See video at 5:40 https://www.youtube.com/watch?v=2vzvWUqUtb8 I noticed another ...
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### How should I select appropriate capacitors to ensure compliance with IEC/EN 61000-4-2:2009 and IEC/EN 61000-4-5:2014 standards for my device?

When applying the IEC/EN 61000-4-2:2009 and IEC/EN 61000-4-5:2014 standards for our device, our consulting firm recommended bypassing the input power jack to the chassis ground using two 33nF ...
• 173
1k views

### Would a room-sized coil used for inductive coupling and wireless energy transfer be feasible?

My understanding of inductive coupling is that it isn't feasible over long distances because the spread of the magnetic field lines happens rapidly, so not much flux will go through the receiver coil ...
• 153
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### Inductive crosstalk mechanism for 2 lines that run parallel on the same layer

According to Faraday's law, changing magnetic field lines that penetrates the victim line must create voltage on the victim line, but if we imagine, we see lines are orthogonal to the victim trace ...
262 views

### How does energy travel in the system in a conducted RF immunity test,?

I have a question regarding some conducted RF immunity (IEC 61000-4-6) tests. We inject noise starting at 150kHz until 80MHz. The signal injected is AM at 80%. The level is 20Vrms. Here is the setup ...
• 536
63 views

### How can I calculate the coupling coefficient between two coils?

I have two planar, circular coils of different number of turns, inductances, and radius, stacked on top of each other. How can I calculate their coupling coefficient (k) based on their properties and ...
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### If the impedance of two coils is measured to be identical at 250.0 kHz, is it safe to assume identical impedance across the spectrum?

This question pertains to matching two air-gap inductors for use in resonant coupling. Alternative solutions are welcomed and appreciated. The two coils shall be comprised of identical wire. The two ...
1k views

### AC coupling to center an oscillating waveform to 0V doesn't work

I have a simple sawtooth oscillating circuit that I would like to center to 0V (remove the DC component.) I have tried AC coupling but the output is still a little to high and not centered. Could ...
57 views

### Impedance of antenna and noise propagation

I would like to better understand how noise is radiated. Suppose the circuit under study is a circuit with a DC/DC converter (source of noise) and an analog circuit (receiver) which is very sensible ...
• 2,478
104 views

### How should I interpret this circuit? [closed]

This circuit is a coupling relay circuit distributed. Looking at this circuit makes sense. Thank you for answer.
1k views

### Why don't WD NVMe SSDs have PCIe AC coupling capacitors?

I see no coupling capacitors on PCIE TX lanes. Is it Safe to Remove Coupling Capacitors? Or Is it possible to make capacitors into the chip? Add more photos：
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### Can I use a 250 nF instead of a 200 nF SMD ceramic capacitor?

Im trying to fix a broken GPU that has a missing 200 nF SMD ceramic capacitor. I found a similar one on a motherboard that has a capacitance of 250 nF. Is it possible to transfer it to fix the GPU? At ...
354 views

### cross coupled nmos pair

For the given circuit, I am observing the source voltage of M1 and M2 as the min of the applied voltage. Here, the current is equal in both fets. But Vg is not the same. So, both cannot be in ...
• 116
147 views

### Coupling 2 buck converter's output to increase output current

I'm quite new working with step-back converters, and I have to use them in the project I'm currently working. My board will have 24V/5A source input, and I want to step-down this tension to 12V, 5V ...
777 views

### Square wave distortion at low frequencies, high-pass filtering, AC coupling

This is an update on my previous question. As Hearth suggeste, I changed to DC coupling on my scope. This is what I got: That's a clear change. Not a perfect square waves but I guess it is because of ...
167 views

### Optocoupler or DC/DC-converter for generation of trigger voltage

In my project I would like to trigger an external device with my electronic trigger system. The trigger voltage of the trigger system is 5 V, while the external device needs 24 V to be triggered. In ...
• 724
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### How to properly couple DC in this biased headphone amplifier design on power-up?

I am a self-study noob to electronics (and audio electronics) but diligently learning every day :) Some things I understand well, others I'm fuzzy on. This device is a headphone amplifier using NE5532 ...
• 145
264 views

### Antenna inductance calculation (RFID applications, inductive coupling)

Inductance of various antenna coils of different shapes can be estimated. Some examples are: A circular coil with single turn. N turn multilayer circular coil. Spiral coil. N turn squae loop coil. ...
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### Do high impedance nodes have higher noise due to inductive coupling as well?

This link clearly explains how high impedance nodes are susceptible to capacitive coupling noise. Is the same true for inductive coupling? As per my understanding, inductive coupling would induce an ...
• 3,032
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### Filter for AC line coupling with audio signal source

I need a sharp notch filter (higher order) for the 50-60 Hz band, to be placed between AC 220/125 V power line and an audio source (not necessarily amplified), such that the input signal from the ...
126 views

### Why am I getting a random offset voltage?

I have query about the following circuit which is an enable for a regulator. This is on a 2 layer PCB. OUT goes to a Schmidt Triggered Inverter to the clock on a D-Type Flip Flop, where the output ...
• 175
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### AC coupling of relay driving circuit - Driving relays using PWM

I have designed this circuit and math calculation works but looking back now I feel the cap is too small may be I am making any mistake here? Can some one explain how to chose the capacitor for AC ...
3k views

### What precisely is the numerical (or any) meaning of mutual inductance and, is it useful, representative (of something) or important?

When we consider two inductors that are magnetically coupled, we sometimes talk about mutual inductance. As an example, consider two inductors (such as 9 μH and 4 μH) that are 100% coupled and produce ...
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1 vote
203 views

### Resonant Transformer / Resonant Inductive Coupling

I´m trying to build a resonant transformer (or a resonant inductive coupler, I don´t know if the names fit to the topology I´m showing, anyway). The idea is to develop a high voltage on a capacitor. ...
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### LED on lamp outlet flashes when switch is off - is this capacitive coupling charging the power supply? And what to do about it? [closed]

I wanted to connect an LED light chain to a lamp outlet in my house in order to turn it on and off using the wall light switch. I have dismantled the 230V to 3V power supply that was built into the ...
92 views

### I’m working with pcf7991at antenna driver ic

Just wondering if you can help me I’m trying to calculate capacitor and resistor values for a 125khz inductor coil . My coil measures 6.8 ohms. I’m not sure how to calculate the capacitor values ...
144 views

I have built headphone amplifier kit and connected it to the output of DVD player. It works but I can hear humming. The humming is present only when DVD is connected. There is no groundig of the boxes ...
2k views

### Backwards compatibility of PCIe AC coupling capacitors

The PCIe base spec mentions that platforms operating only at 2.5GT/s or 5GT/s may use AC coupling capacitors in the 75nF-265nF and that platforms supporting 8GT/s and above must use 176nF-265nF. ...
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1 vote
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### Why there is capacitor in series in high speed designs like SGMII?

Why we are connecting capacitor in series in high speed designs like SGMII. If it is to remove DC voltages, why we are not using on other signals like I2C, SPI and so on. What is the major purpose. ...
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1 vote
499 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 ...
298 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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### 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 ...
128 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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### 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 ...
571 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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1 vote
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### 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 ...
1 vote
14 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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### 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)? ...
122 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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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{...