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

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47 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 ...
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19 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 ...
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1answer
35 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 ...
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1answer
67 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 ...
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3answers
63 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 ...
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1answer
32 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 ...
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44 views

How to remove noise from the output of inverter circuit created from 741 IC [closed]

I'm trying to provide a negative input to ADC0804 through an inverter circuit. The inverter circuit is made using IC 741. But, the inverter circuit is giving a lot of noise. Is there any way to ...
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2answers
127 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 ...
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0answers
31 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
38 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
29 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 ...
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1answer
79 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 ...
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1answer
54 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 ...
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2answers
189 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 ...
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0answers
31 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
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2answers
72 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
44 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
125 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 ...
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3answers
139 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 ...
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1answer
35 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 ...
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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
58 views
0
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1answer
32 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 ...
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1answer
56 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
87 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 ...
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1answer
71 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 ...
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2answers
263 views

Noise caused by improper decoupling of VDD pin

I have posed a question, "Function run in MCU generate noise to the analog circuit", before but at that time the question was not detailed enough. After several days` of testing, the problem is now ...
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1answer
44 views

USB switching power supply filter

Good afternoon fellow students of life, I have a particular question that relates to the use of a Duracell USB switching power supply as the main supply for a high sensitivity sensor board. Most of ...
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0answers
25 views

What is a cheap way of isolating a large parallel plate capacitor from background fields

I am making liquid level detector that will rely on a change in capacitance to determine the changing heights of various solutions in a tube placed between two stainless steel plates(20cm x 12cm). I ...
0
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2answers
90 views

Function run in MCU generate noise to the analog circuit

As my circuit is a little complicated, I don`t know how to pose the PCB here. So I just want to know the probable causes of the problem and I will test them one by one later and report back. My ...
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0answers
41 views

Noise on a tda2003 circuit

I've built an amp using TDA2003. If I use a common 9V battery, it works nice, with very low noise. But, if I change to a power supply (that I borrowed from a cell phone charger) that delivers 8.4V ...
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1answer
62 views

Noisy sensor on a prototyping board

I made a small prototyping board where accelerometer data is read into a microprocessor, showing the data from the accelerometer after it is sampled, gives a very noisy signal. (50 mv peaks) I had a ...
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3answers
55 views

Removing spikes from multiple onboard power supplies

I have a board that is based around an STM32F303 and am using the onboard ADC/DAC, fed by a 3V power supply derived from a USB 5V input. The 5V also feeds a module, RD0515, which creates +/- 15V for ...
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42 views

Possible ways of protecting comparator input from coupling?

Overview So as I'm implementing some logic with a comparator, I've run into the problem of the output swing coupling with one of the inputs, and now I'm searching for possible ways to minimize or ...
7
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1answer
159 views

How serial resistors actually reduce EMI?

I am recently working with a GSM based system, and there was this advice in the datasheet of the GSM module: 22Ω resistors should be connected in series between the module and the SIM card so as ...
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2answers
81 views

Can a malfunctioning relay in an amp cause or allow a speaker to crackle when turning the vol potentiometer? [closed]

Ok, so this question has several layers, I admit it. I recently acquired a Lepai 2020A+ amp. It is, I believe, the latest version PCB because it has the two relays for speaker protection instead of ...
0
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1answer
71 views

Inverting Opamp on Noisy Ground. Would an LC filter help?

Alright, say I have this Inverting Opamp, but it so happens the positive input to ground is also connected with another sub-circuit that happens to produce a lot of noise (no pun intended): ...
0
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1answer
63 views

Stop earth from introducing noise to piezo circuit

I am currently prototyping a circuit which measures pulses on piezo-electric sensors; however, I seem to be having an issue with noise. When the circuit is battery powered (and therefore floating), ...
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69 views

Does anyone know why DC-DC converter have noise

I am running an issue that my custom board has noise come from DC-DC converter after running a while. I used V78W-500 as the DC-DC converter and already replaced a new one. Except noise, the voltage ...
2
votes
1answer
68 views

Sonar single transducer element SNR vs array SNR

Background: I'm taking a flexible learning unit on radar and sonar systems in a vocational college for an assoc. degree level course. The teacher has given us a reading assignment: "Chapter 15 ...
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1answer
173 views

Noise on TL074 / TL084 but not on LM324

I made a circuit that modifies a signal so it can be safely read by an ADC. I'm using an op amp to shift the signal +2.5V so I can measure AC. When I do this shift another signal appears. About 40mV ...
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1answer
66 views

What does zero-mean noise mean? [closed]

I asked this question about zero-mean noise on Physics Stack Exchange and got this answer: Zero mean so that the noise does not present a net disturbance to the system. There's as much positive ...
3
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2answers
93 views

Does transformer humming cause notable waste of energy?

AFAIK transformers hum because alternating magnetic field causes pieces of laminated core to slightly deform and vibrate and that is simply a byprocess of how transformers work. However for the same ...
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1answer
60 views

ADC outputs random values to constant input

I am using ADC (ADS7822) from TI and I have some strange behaviour with it. Below diagram explains the voltage inputs and connections. I was reading strange values with this setup. I removed ...
2
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1answer
62 views

Ground Plane Noise?

I have some noise issues on a PCB that I am having a hard time troubleshooting. Below are pictures of the schematic as well as 2 scope traces. The first trace shows the amplified signal with the noise ...
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1answer
54 views

Tunnel diode I-V curve noise [closed]

Wikipedia gives this example of an I-V curve of a tunnel diode. What is the "noise" in the negative resistance region? Is it a characteristic of the diode or of the measuring circuit? The caption says ...
3
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1answer
163 views

Micro controller reset due to noise, PCB design for noise immunity

After making this PCB, I learnt the importance of ground plane. Besides ground plane, there is considerable amount of theory behind PCB designing which can provide immunity against ESD, surge, EMI, ...