About issues caused by electrical noise, or improving the Signal/Noise ratio of an analog circuit.

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37 views

Are there ready-made boards with DSP targeted to active noise cancellation? [on hold]

I would like to play with active noise cancellation but I don't know what tools to use to begin with. My application would be simple ducts, or low-frequency and narrowband noise (compressors, for ...
1
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2answers
68 views

I2C Bus is Not Responsive When Engine Is Running. How to Diagnose and Fix?

I've got a solder-less bread-boarded prototype microcontroller with a few I2C devices that take some measurements on a motorcycle. For now, The MCU is powered by a LM7805 with decoupling caps near the ...
0
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1answer
57 views

Old cellphones versus new cellphones noise [on hold]

Why older cellphones cause impulse sounds in our loudspeakers, but new cellphones not? Why these impulse sounds can be heard in our soundspeakers?
1
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0answers
34 views

How can I calculate the noise in a simple RC high-pass filter?

How can I calculate the noise in a simple RC high-pass filter? (Assuming very low input impedance and very high output impedance.) I know the Johnson noise in the resistor should be 4kTR, but I'm ...
0
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1answer
79 views

Too noisy ground

Here is noise on the ground of my pcb taken from two point: Yellow line is "Point 2". Blue line is "Point 1". Here is that points on pcb: There is Altium filled ground polygon. It seems that it ...
0
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1answer
49 views

Ringing in OPamp OutPut

I am using this Differential In/Out Opamp circuit as ADC driver and to provide some gain(G=6.4). The component values are R53,R52=100, C28, C27=1.1uF, R56= 1K, R57=open, R55,R54= 2K7, U6=OPA2211. ...
4
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1answer
66 views

Would low frequency signal (10kHz) have reflection on conducting wires as well?

I am connecting a signal source of 10kHz sine wave with a driver which is a voltage follower made by an OpAmp. The follower has one input and two identical outputs. One output is connected with a ...
0
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1answer
34 views

Increasing voltage noise but decreasing current noise with rising resistance

Consider the two (equivalent) formulas for the noise power spectra of a ohmic resistor: $$W_u(f)=4kT\cdot R~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(1)$$ and $$W_i(f)=4kT\cdot ...
2
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2answers
320 views

Using PC audio to listen to electrical noise on power line?

I have done a bit of research on digital filtering and I was wondering if it would be possible to use the audio hardware of my computer tu listen to the electrical noise on my powerline ? If it is ...
-1
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1answer
39 views

Effect of air signals over a cable [closed]

I want to know the effect of air signals (like am/fm radio signal) over my long wire (~100m long ~6mm^2 diameter). If i use band pass filter at radio frequency, how much voltage noise can i observe ...
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1answer
29 views

Noise when Charger Connected [closed]

I have a handheld rechargeable Measuring Instrument. When I use it normally, without charger connected, readings on screen are stable. But when I connect the charger into it (It's a 5V USB charger) ...
0
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1answer
36 views

General suggestion about how can I cancel the noise

I have designed a board and I have six relays on it, so I am scared that maybe when relays want to switch, my micro-controller (ATMEGA32) will stop working. I have used a diode and also a ferrite ...
0
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1answer
41 views

Which bypass cap position creates a cleaner voltage and current feedback circuit?

Is the following true? Caps = 2, 1800 uF Nichicon, Manf Num UHE1V182MHD3, CAP ALUM 1800UF 20% 35V RADIAL. "you want your bypass caps as close to what you are bypassing with the least series ...
2
votes
1answer
76 views

Analog & Power Ground Planes Doubts

Working on a new board, I have to face some requirements to ensure the performance of the whole system once is manufactured. PCB is a 4-layer one, and it has both analog and digital components. But ...
1
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0answers
23 views

How to tune PID for a Y(t) = k*X(t) system?

Could I have your opinions on PID type selection? System description Here comes a very simple system: Output(t) = \$ k * (Input(t) + systemVariable(t)) \$. \$k\$ is constant and ...
0
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0answers
97 views

How to generate sine waves with least 2nd harmonic distortion(with DAC)?

This thread has been updated on 14th, Aug, 2015 I am using this chipAD5542A, which is a 16-bit DAC to generate 1k sine waves around 100mV. Sine tables of 32 numbers are used inside a MCU, combining ...
1
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0answers
27 views

AC Noise in UTP cable for Wiegand26

I have situation where i need to capture wiegand26 signal. I use it on single twisted pair. But i get a lot of AC noise in UTP cable Cat 6. Shield is not connected anywhere. The ...
0
votes
1answer
70 views

Noise Matching transformer

I'd like to use a transformer to improve the performance of our SR5184 preamp. The signal recovery SR5184 is an ultra low noise preamplifier. It has 0.8 nV/ √Hz input noise and a bandwidth of 0.5 Hz ...
1
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1answer
46 views

Unity gain op-amp buffer, single supply - potential problems?

I need to precision buffer a DC (or slow changing) voltage of around 2.5V using an opamp in non-inverting unity gain mode and driven from a single supply using no resistors. Supply voltage is 5V. Is ...
3
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2answers
892 views

Skin depth at 50 Hz is much longer than the thickness of the shield of a coax cable. Then how does it work?

The title already narrates the question. We know that using a coax cable for audio amplifier input remarkably reduces 50 Hz noise. However the skin depth of the EM radiation at 50 Hz for copper is ...
2
votes
1answer
47 views

Relay EMI. Should I be worried?

I am using PCB soldered relay to switch 8-10A 220V appliance. Out of curiosity, I tried to visualize the EMI being radiated from arc sparking. I attached the GND to Neutral pole of proble and kept the ...
0
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0answers
33 views

Switch Mode power supply and ADC measurements

I've got a controller, measuring on 4 channels, but I see the (~50mVpp)ripple of the power supply, when I oszilloscope the ADC pin. The adc values jump around too. I tried to add an LC filter, but it ...
0
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1answer
49 views

DAC quantization noise on DC output

Does the output of a DAC have quantization noise when outputting a DC voltage value? It seems to me that it will not as long as the DC value does not fall between two output levels of the DAC. All ...
0
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0answers
23 views

Arduino + 4051 -> noise on certain 4051 pins

I am trying to use two 4051 ICs with an Arduino Micro right now. The idea was to have an 16-sensor demo station (8 sensors per ...
0
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1answer
43 views

pseudo differential input of amplifier

The Signal Recovery Model 5184 is an ultra low noise preamplifier. The product description says ... and incorporates a special pseudodifferential input stage that can be floated to give the ...
0
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1answer
68 views

Is It Okay to Run a Single-Ended 5V Pulse Train through One Strand of a Twisted Pair?

Okay, I have a motion control application that I want to wire up. The motor drives run from single-ended step and direction signals. I am designing a circuit board, and was thinking of using 8-pin ...
1
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3answers
69 views

Electrical noise sources in farms

I am designing the data logger of a solar-powered automatic weather station that will be installed in farms. It's used to gather data from environmental sensors (wired) and send it to a host using the ...
0
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1answer
42 views

Understanding input voltage noise of AD8232

AD8232 has a built-in instrumentation amplifier with a fixed gain of 100. I am interested in using this device for amplifying EEG signals. Page 3 of the linked datasheet describes input voltage noise ...
0
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2answers
135 views

Noise resistant microcontroller used in high power inverters for PWM generating [closed]

In order to generate PWM pulses for driving switches of a high power(80 kW) three-phase inverter,which microcontroller family(and which member) is suitable? ,taking into account the noise effects on ...
2
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0answers
38 views

Low Pass Filtered Noise Power Spectra, Showing Low Power @ Lowest Frequencies

White noise is being passed through a voltage follower, then filtered through a simple first order low pass RC circuit (C=0.5 micro Farad, varying resistance between 2k-10k, ohm depending on RC value ...
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0answers
74 views

Tips for improving this PT100 sensor amplifier circuit?

I'm designing a circuit to read a PT100 temperature sensor using an OP-amp and the ADC of a PIC 16F1788. I've designed the following circuit: The PT100 sensor is labelled PT100. The basic idea is a ...
0
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1answer
34 views

Expected repeatability of PT100 temperature sensor

I'm designing a circuit to measure temperature using a PT100 sensor. I'm putting 1mA through the sensor, and measuring the voltage drop. Assuming a perfect voltage measurement, what would be the ...
1
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1answer
100 views

Mixed signal Microcontroller grounding

I have a circuit with split ground planes one for analog, and one for microcontroller/DC-DC etc. The microcontroller will be using its ADC to sample from the analog circuitry. Ideally I would like to ...
0
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1answer
57 views

Power rail decoupling caps for analog circuitry

First off, the terminology I'm using could be complete rubbish - I'm still learning I have a mixed signal board for measuring bio-signals. The 4 layer board will have a split ground plane, analog ...
0
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2answers
190 views

How do I increase the signal to noise ratio in a true condenser microphone?

I made a simple condenser mic as a test project for something more functional. However, when I connect my microphone I only hear the mains hum. Using a factory-made condenser I hear the mains hum ...
0
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0answers
36 views

LCD Flickering when Shielding is not Connected to Ground

I got myself one of these LC-Displays: http://www.sainsmart.com/sainsmart-hdmi-vga-digital-9-9-inch-1024x600-lcd-driver-board-for-raspberry-pi.html It's a barebone LCD setup with just the components ...
3
votes
2answers
82 views

Coaxial cable vs shielded pair

I need to wire a sensor with analog output to an acquisition system, and the presence of a separate "shield" connection on the DAQ made me thinking: why would I use a shielded 2-wire cable versus a ...
1
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1answer
45 views

In current mobile phones, what are some specific techniques that prevent handling noise (rubbing, jostling) from being picked up by the microphone?

I've noticed that when using my smartphone the vibrations from my actions aren't picked up, or are picked up very faintly by the microphone. I've worked quite a bit with microphones and I know it must ...
2
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3answers
131 views

Debugging when oscilloscope grounds cures the problem

In a nutshell : My circuit behaves erratically I connect the 'scope to find out why The problem disappears In particular, this concerns the circuit in my last question although this is not ...
6
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3answers
143 views

60Hz “click” or clipping noise when differential amplifier is surrounded by salt water

I am a graduate student attempting to take electrophysiology recordings from a lobster under water. In the current set up I am using, two differential amplifier boards are attached the the lobster's ...
1
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1answer
39 views

GSM module noise

I'm developing an embedded system that uses telit gl865 modem to connect to a server using gprs. I've noticed that the module makes a strange noise when connected. It's the same noise I used to hear ...
0
votes
1answer
41 views

Where and how do I put an inductor on a volume control

I built an stereo equalizer but I made some mistakes. As the potentiometers didn't fit on my PCB I had to put them separated and make the connections with some wires. The other mistake is that I made ...
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2answers
63 views
0
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1answer
36 views

Low current more susceptible to noise?

Supose I have an opamp with pnp input stage (constant current flowing out the input pin), like the following: simulate this circuit – Schematic created using CircuitLab Would the input ...
17
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4answers
1k views

How to clean up a noisy signal?

I'm controlling a 4-pin PWM PC fan from a PIC16F684 with the fan speed driven from an ADC reading of a proximity sensor. This all works ok. I wasn't originally planning to use the tachometer output ...
1
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1answer
57 views

Am I getting DC bandwidth correctly?

I am computing Johnson and shot noise in a DC circuit, where I have an Arduino Due sampling with "delay(100);", i.e. at 10Hz. Sampling rate and bandwidth follow Nyquist sampling theorem. According ...
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0answers
41 views

Low-noise SPDT switch

I need to produce an extremely low noise SPDT switch. This switch will take two different inputs to a single 16 bit ADC. The inputs are 50 ohm BNC outputs from trans-impedance amplifiers. The ...
0
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1answer
75 views

misunderstanding from definition of SNR

We know that SNR is defined as "power" of the transmitted signal to the "power" of the noise. In practice we transmit time limited signals (for simplicity consider the case that there is only one ...
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2answers
90 views

Concept of noise floor

Can anyone please explain the concept of noise floor. If we want to design an active high pass filter with a cut off frequency of 12 kHz and pass band gain of 2, how do we apply the concept of noise ...
0
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1answer
93 views

Motor noise interfering with I2C

I built a robot using the Arduino Due with all the sensors running at 5V over I2C. There is a level shifter on both I2C lines. The motors are controlled using a VNH5019 motor driver carrier from ...