# Questions tagged [capacitive-coupling]

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### Detecting 220vac with optocoupler and microcontroller on lines that have capacitive coupling voltages

I'm a hobbyist, trying to instrument my heating system so that I can control a three position valve. I have an ESP8266 integrated with a DRV8825 stepper motor controller, and a no-name Chinese 220vac ...
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 ...
2k views

### What is the "problem" with directly coupled amplifiers?

As in the title, my question is basically about understanding what is the "problem" with directly-coupled (below, I will use dc for "directly-coupled" and DC for "direct ...
• 1,151
376 views

### CE Amplifier problem

I am new to learning about electricity and I was trying to make a common emitter amplifier. I did some research and I tried to make the circuit. The circuit amplified the signal but the signal was not ...
84 views

### Why isn’t my overdrive circuit working?

I have attached an image of an overdrive circuit that I have designed for a guitar pedal. I have built the circuit and it isn’t working and I wanted to find out if there were any obvious design flaws/...
1 vote
232 views

### Un-biasing transistors

To amplify small signals, NPN BJT must be operated such that Vb + VsigLowest must be greater than the voltage drop of Vbe (~0.7V). How do we center the resulting voltage Vce around 0?
• 115
366 views

### What went wrong with this class A amplifier design?

I was trying to build a normal class A amplifier, but no matter how hard I try, I cannot find the reason behind my output (blue line) being clipped at the negative cycle of the input (yellow line.) ...
31 views

### Calculating AC-Coupled input current

I'm using an SDR which uses and ADF4002-based PLL with its REFIN input AC-coupled via a 0.1 uF capacitor to an external input. I'd like to connect an external reference clock to it, but I'm unsure how ...
• 101
2k views

### Why do we need R1 in a non-inverting op-amp?

I am quite new to learning op-amps. What is the purpose of putting R1 there? Does this have any meaning in the design of a microphone amplifier? I read about this from another answer, which says that ...
• 91
123 views

### Human body communication, magnetic vs capacitive coupling

I am reading a paper by Park and Mercier called Magnetic Human Body Communication (2015). They are looking into human body communication techniques and compare magnetic human body communication (mHBC) ...
• 376
1 vote
429 views

### Implementation of a capacitive coupling circuit for power line communication (PLC)

Introduction: Hello everyone, I just wanted to see if there is anyone out there who is familiar with power line communication technology that can help me figure out what is wrong with my LTSpice ...
• 21
1 vote
362 views

### how does AC coupling eliminate the ground current problem between data source and destination in FPD_Link II I/F?

Reading about FPD-Link II in Wikipedia, I came across this statement for which I need clarification: Because the signal is DC balanced the application can use AC coupling, which eliminates the ...
• 639