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Questions tagged [common]

The tag has no usage guidance.

0
votes
1answer
128 views

Sound distorted from amp configuration, and one transistor variety getting too hot

The sound is distorted from my configuration. The transistor I'm using is an MPF4393. I need to add resistors and capacitors and how do I get more power (to make it louder) What should I add? Also ...
0
votes
1answer
26 views

Analysis of 3 Stage CS Ring Oscillator

I am new to the world of oscillators, so take it easy on me. I have been attempting to analyze the following common source ring oscillator: However, I am having some trouble here. So based on my ...
0
votes
2answers
57 views

Does Differential Amplifier Emitter behave as ground in AC-analysis?

I am trying to solve various differential-amplifier homework problems for which I have the solution to study. For the simplicity of most problems we are able to neglect base-currents. Moreover, it ...
0
votes
1answer
49 views

mains earth and op-amp ground

I was trying to power a transimpedance amplifier built with an op-amp on a protoboard. I only had a power supply that looked like the first image below (no COM, which I would have connected to GND ...
2
votes
2answers
365 views

Power supplies with or without 'COM' and without ground port at all

This is probably something really simple, but I wasn't able to find the answer yet. I've been using a power supply with both COM and earth ground, like the first image below. To power an op-amp, I ...
0
votes
1answer
115 views

Common mode and differential mode

I can't understand how to apply common mode and differential mode concepts. 1) I know that if I have two signals v1 and v2, I can always write them as: v1 = vcm + vd/2 v2 = vcm - vd/2 Example: v1=...
0
votes
1answer
239 views

How to build a three-phase common mode choke in Matlab simulink?

How to build a three-phase common mode choke in Matlab simulink? Should I use the mutual inductor?
0
votes
1answer
80 views

Homemade EEG Circuit Common mode feedback

https://sites.google.com/site/chipstein/home-page/eeg-with-an-arduino/assembling-the-arduino-eeg-circult Hi, I am currently building a DIY EEG circuit using the guide above. This guide is for when ...
0
votes
1answer
56 views

University Project - Common Mode feedback in EEG systems

Basically EEG signals (potential from brain) contain 'noise' due to EMG signals (potential from muscles). I was thinking of using the EMG as a common mode feedback prior to the amplification of the ...
1
vote
2answers
616 views

NPN or PNP transistor for Common Cathode Seven Segment Display LEDs?

I've read a bit about this but there seems to be much ambiguity. When using common cathode seven segment display LEDs would you use NPN or PNP? Or can you use either? Can someone please give a ...
0
votes
0answers
166 views

Common Mode Noise in Isolated System

I am working with an isolated system (battery powered with no GND connection), but am seeing common mode noise (40-85MHz) on cables during radiated EMI testing. Cable ferrites reduced levels ...
1
vote
2answers
673 views

Differential ADC and Common Mode Voltage

I am trying to understand a little bit more about common mode voltage. I am working with a particular MCU, the TMS320F28377S, and it has a common mode voltage requirement for its positive and negative ...
2
votes
1answer
1k views

Can a 6 volt positive ground system share a common chassis ground with a 12 volt negative grd

I am working on an antique car that has a 6 volt positive ground electrical system with the exception of the fuel gauge which is a 12 volt negative ground. Currently the car has a voltage converter ...
8
votes
4answers
1k views

Can I use a common mode choke as a coupled inductor in a SEPIC converter

I do not really understand the difference between common mode chokes and coupled inductors. They are both 2 coils wrap around the same core but I know they have different purposes. I want to design a ...
1
vote
4answers
1k views

Digital current affect analog signal, but why not the other way around?

my course text only says that if we have a conductive coupling then the digital current will affect the analogue signal because it causes certain voltage drop at the common wire. But it doesn't say ...
2
votes
1answer
128 views

Split Common Neutral for DC Current

I have a motorcycle headlamp that I am lighting outside of a motorcycle. It's a stage prop, I have the front end of a motorcycle built as my microphone stand. The bulb has hard set 3 terminals, two ...
-2
votes
1answer
549 views

Common ground with two bridge rectifiers [closed]

I have a transformer with multiple taps on the secondary coil deliverin many different voltages and I want to know if I blow something up when I convert the AC of the transformer to DC with bridge ...
1
vote
3answers
1k views

Battery Wiring - 3 Independent systems with common ground

Background: Building a radio control wheel bot. Using a motor controller that recommends independent power supply for 1.) power to the controller and 2.) power to the motors. Also want a 3rd power ...
1
vote
1answer
122 views

Linear and Switched-Mode Supply Common Shared

We have a mixed mode PCB system with both digital and analogue systems. Due to high speed they all share the same ground on the PCB, but use logical spatial separation to control noise. SO PCB input ...
7
votes
1answer
7k views

How to use common mode choke inductors? (differential vs common mode)

I have yet to undestrand exactly how to use common mode chokes inductors, according to the datasheet they have 2 operation modes like in the picture common mode and differential mode, however im ...
-1
votes
1answer
253 views

NPN switch: What is wrong with this circuit?

I'm trying to use a single source for both output and an NPN switch (5V - 2Amp). I cannot get higher than 500mA at the output, with VLoad about 4.3 V max. simulate this circuit – Schematic ...
0
votes
2answers
583 views

Amplifier gain too HIGH?

I have this circuit : Two common base amplifiers for amplifying frequency in FM range (88 to 108 Mhz). The Problem is, as seen in the figure, I am getting an output of 1.5 V for an input of 10 uV. ...
0
votes
1answer
640 views

Time domain of a Sine wave?

I am working on a lab in school with a common source JFET amplifier, and I needed to express \$v_{out}\$ in terms of time domain. If \$f\$ is the frequency and \$T\$ is the period, then I need $$v_{L}(...
-1
votes
3answers
1k views

Question about common emitter configuration?

The configuration of the common emitter amplifier is one resistor at the emitter, on resistor at the collector, two bias resistors at the base as shown in this picture : I saw this new configuration, ...
-1
votes
2answers
16k views

how to choose resistors' value for common emitter amplifier? [closed]

I want to choose the best values of R1 , R2 , R3 and R4 to get the maximum gain (high performance). I design the circuits practically, so I don't need to do a lot of calculations. I want the ...
1
vote
1answer
408 views

Confusion on common node in a circuit

I am a bit confused related to the concept of common node in a circuit. I know that all voltages are measured with reference to this node. But here's the problem : I have some big circuit, ...
0
votes
2answers
279 views

MOSFET amplifier

I found the following problem in the Rashid book of microelectronic circuits. I am looking to solve it but I don't even know where to start. How can I solve everything? What results do you get so I ...
3
votes
3answers
202 views

Why is KCL giving me the wrong solution?

I'm trying to derive the gain of the following common base amplifier circuit: To do this, I drew the equivalent T-model circuit: . The problem I have is that I get two different transfer functions ...
0
votes
1answer
119 views

Microelectronics NMOS amplifier

I am trying to solve a Sedra/Smith problem involving NMOS transistors. Given that both transistors are biased at the same point. Question is to find \$g_{m2}, i_d, v_{d1}\$ and the value of \$R_D\$ ...
1
vote
1answer
204 views

Charge Arduino through Computer but connect to external circuit

I'll explain what I'm trying to achieve first. I basically want to control a 4 wheeled robot through an Arduino but I need the Arduino to get the commands from a computer. I've already setup the ...
7
votes
5answers
33k views

Common vs. ground

I've been trained to use the word ground and the ground symbol to refer to the earth, the dirt on which we stand. Circuit common is considered to be a separate concept, with the symbol . My ...
1
vote
2answers
2k views

Common ground : Computer A and USB powered Arduino ( MCU ) from Computer B

I have 1 computer, 1 laptop and usb powered arduino ( MCU ). Arduino is connected to laptop via USB cable. Laptop is connected to 220V wall or runs from batteries. One PIN from arduino is connected ...
1
vote
3answers
2k views

Why common-mode voltage is avarage of two input voltages in a differential amplifier?

I'm having hard time to understand the motivation behind the common mode voltage in differential amplifiers. I came to learn that common-mode voltage is chosen (v1+v2)/2 where v1 and v2 are input ...
1
vote
2answers
342 views

How to achieve common ground for a single ended input?

I'm using a current loop transducer as in the set up picture I provided. The transmitter is regulating the current proportional to a physical quantity and regulating the current. It is a typical 4 to ...