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

learn more… | top users | synonyms

0
votes
0answers
55 views

Can this op amp circuit easily be modified to provide differential input?

I have a "noisy ground" problem which seems to be essentially the same as the one described in this old post: Ground loop? Switch mode power supply noise The solution (as provided in the answers to ...
1
vote
2answers
91 views

Are all USB “audio adapters” DAC's? Can USB ports be used for analog output?

Kind of a weird question.. Background: My motherboard has started producing weird static(buzzing) noises on the audio output(3.5mm jack), it's not noticeable when using headphones, but on speakers it ...
3
votes
2answers
303 views

Noise at 2^n transitions

I am sampling a video signal from a linear imager. I noticed when the illumination is just at the intensity when the ADC increases by another MSB bit at the output, the noise occurs. That is, when ADC ...
2
votes
2answers
288 views

I/O series resistor

I've read that digital I/O pins should have a resistor in series in order to limit noise. Should one also use such approach when interfacing with the I/O pins of an arduino, or is that already done on ...
1
vote
2answers
59 views

Switching regulator PCB layout

I'm putting together a buck regulator (first time around) based on the lm2374 chip. TI provides gerbers of a recommended layout for this chip family, but my configuration differs a bit. I've read up ...
-1
votes
1answer
50 views

Static in earphones when scrolling with mouse [closed]

Why do I sometimes hear faint static in my headphones when I scroll with my mouse? I have noticed this on multiple(4) computers, with Windows 7 and 8. Does anybody else notice this? It happens when I ...
1
vote
1answer
50 views

instrumentation amplifier output noise

I have a low level DC signal from a thermopile sensor of 0-9.1mV with 7uV increment. I feed this to an INA114 instrumentation amplifier with gain of 550 to get 0-5V output. I tried introducing RF ...
-1
votes
3answers
79 views

SPI on long wires with current control

I need to control a 5V CMOS SPI device in my car, but the microcontroller distanced by 5 meters of wires. I googled that standard solution for my problem is differential lines like RS485. But I don't ...
1
vote
2answers
144 views

Noise control in op-amp circuit design by using low spec op amps

I have a rather strange problem. I have a breadboard circuit on a double sided PCB with plenty of ground plane and a good well decoupled power supply. I am amplifying a small medium frequency signal ...
1
vote
1answer
61 views

Best method to eliminate alternator whine from a 12V line?

I've purchased a Miccus Mini-Jack Rx BlueTooth audio receiver. This device will accept a bluetooth signal from my phone and output it to a headphone jack that I plug into the AUX-In on my car stereo. ...
4
votes
2answers
464 views

Why does reversing the oscilloscope probes cause ringing in the signal?

I am measuring a PWM signal in an oscilloscope using probes with a 1X and 10X switch (active?). I'm measuring across a resistor which is in series with an LED which is driven by an NPN 2N3904 ...
9
votes
3answers
648 views

Does a pin jumper adds noise?

When designing a PCB, is it sensible to use a pin jumper in the pathway of a small current signal (around 0.8 uA) or could there be issues with noise? I would use the jumper to select between ...
4
votes
3answers
192 views

Ferrite bead position

I wish to use some extra power supply filtering for my DAC, ADC, CPLD and OpAmp devices. In this question I got the point about the global locations for ferrite beads. If I understood correctly, the ...
0
votes
1answer
70 views

How to calculate RMS of total noise from digital Oscilloscope (FFT)?

Only the red channel is in consideration. The yellow curve is not relevant, which is only another channel of the oscilloscope. The image above was captured from a digital oscilloscope. The vertical ...
3
votes
2answers
151 views

Replacing a FET to avoid the body diode (audio switching)

Here is a circuit I've found online for switching a guitar signal, it uses a mechanical relay in order to rout the signal through a sound processing unit or around it, bypassing the circuit. ...
0
votes
3answers
79 views

Signal to noise ratio for a non-physical property

The signal to noise ratio for a voltage, current, or power is easy to understand, but how do I calculate the SNR when the signal is not a physical property, but instead an abstract quantity? I'll try ...
1
vote
1answer
68 views

Weird samples from SAR ADC

I am playing around with some SAR (Successive Approximation) A/D-converters. I have made a test circuit where I have a 16-bit DAC from Texas Instruments (R2R-based) and an 16-bit SAR ADC from Analog ...
1
vote
1answer
99 views

NRF24L01+ false detection

I use a NRF24L01+ module configured for receiver, 3-bytes address, 1-byte CRC, 1 Mbit/s, channel 2402 MHz, 2 pipes listening. Addresses are non-trivial (0x525443 and 0x4d4252). But when transmitter ...
0
votes
1answer
113 views

Can I set thresholds for 74HC14N (6 NOT gates)? and use as schmitt trigger

I'm trying to convert sine-like wave from IR sensor(quadrature wheel encoder) into square one. Can I make it with 74HC14N(set some fancy RC configuration) or should I use op-amp configuration to be ...
0
votes
2answers
64 views

Low noise amplification - Op Amps vs Transistor based amplifiers

Whats the best amplification strategy to use for something requiring very low noise like an EEG (brain wave detecting)? Efficiency isn't really an issue. Op amps with high CMRR are expensive, and ...
0
votes
1answer
48 views

Current Monitors for Avalanche Photodiodes

I've come a across a document by Linear Technologies that suggests several circuit schematics to interface with an Avalanche Photodiode (APD). They are referred to as current monitors and placed ...
1
vote
4answers
73 views

High input impedance devices - induced noise sensitive

I am currently reading about 4-20mA current loops and the reason we use them .As stated there , using voltage to transmit signals we get voltage drops over long cables due to cable resistance. We ...
1
vote
1answer
146 views

Any tricks to generate triangle wave to add to analog signal for oversampling?

I want to increase the effective resolution of the ADC by oversampling and decimation. Unfortunately the signal I'm realing is too clean, so I would like to add a bit of artificial noise (1LSB peak to ...
1
vote
2answers
99 views

Power supply noise caused by external heat pad

I have a circuit that switches a 50W Sunbeam heating pad via a relay (for regulating temperature). My circuit is driven by a 5v AC/DC switching converter. The AC input to the power converter is shared ...
1
vote
2answers
100 views

Simulating accelerometer noise

I would like to create a software simulation of an accelerometer (MPU-6000). As part of that simulation, I need to model the noise on the accelerometer signal. According to the datasheet of the chip, ...
1
vote
1answer
52 views

Does NI Multisim simulates op-amp input and output noise?

I just created a circuit with AD620 in-amp and I'm worried that there is not enough noise. I wonder if Multisim simulates advanced op-amp/in-amp properties, like input noise and such? I mean, if I ...
1
vote
3answers
199 views

the causes of Fading of signals

I have read about fading of signals , and I have notice that the major cause of fading is multipath , but I have ask myself , what about attenuation , noise and free space loss , all of these make the ...
0
votes
1answer
56 views

How much is the noise of a multiplexer for analog inputs?

I have 4 sensors, each have with two differential output (S- and S+) that I need to use in a differential amplifier (with a gain equals to 1000 in my case). The difference between S- and S+ is ...
0
votes
0answers
77 views

Demanding design on bandpass filter/ Notch filter with gain

I have posted a related question before, which can be found here: Very low noise high pass filter design However, since a different stage is to be considered, I started this new post. We are not ...
0
votes
4answers
249 views

Very low noise high pass filter design

We are trying to design a high pass filter, which mainly goals are: very low noise. Low noise is the first concern. suppresses 1kHz by around 50dB and passes 2kHz. Gets rid of DC Dont care on other ...
0
votes
1answer
158 views

How to filter low frequency noise on power supply from ChipCorder?

I've built a circuit using an ISD4003 ChipCorder, which is an IC for recording and playback of audio (in a telephone answering machine, for example). I've written code to send the SPI commands to ...
2
votes
3answers
327 views

Fighting overshoots/undershoots using ferrite beads does not help?

I posted relative problem a while ago here but we came to conclusion that the overshoots were just artifacts. Later, when I extended the signal lines, the overshoots increased and were about 2V of ...
0
votes
1answer
130 views

Will motors cause more noise when connected to a ground plane instead of directly to batteries?

I am making a small robot using an Arduino and two servo motors. There are two ways that I can provide power to the motors: 1) Run power and GND wires from the battery holder to the motors, then ...
0
votes
1answer
39 views

Is the Delay in Strain Data Due to Capacitance?

I have designed a sensor board which gives a strain o/p based on wheatstone bridge principle(change in stress is measured through change in resistance). But the starting value is not at zero level,it ...
4
votes
1answer
103 views

How can I track where this 471kHz noise is coming from?

I'm new to EE in general and I just received my first oscilloscope (Rigol DS1102E). Anyway, I'm building an audio circuit using an Arduino Micro and the infamous ...
2
votes
1answer
252 views

Clean DC power design for very high precision circuit

We have been designing a very high precision control circuit for quite a while. And we are thinking to make it much easier to use, which is to get rid of the Lab DC Sources and use AC to DC switching ...
0
votes
1answer
102 views

Curious noise on FPGA Microcontroller connection

I have the following setup: An FPGA eval board has a daughterboard with pin headers connected to it. From these headers I have connected 16 ~10 inch 24-gauge wires to feed a bus to a TI OMAP-138 ...
1
vote
2answers
143 views

Filter 50Hz hum picked up by the oscilloscope

I am measuring huge 50Hz oscillations on my oscilloscope, but I am not entirely sure the probe is generating those by behaving like an antenna (an ADC at the same point gives stable values but it's ...
3
votes
1answer
91 views

Can unwanted coupling drive signal lower than intended?

Let's consider the following schematics- a switch connected to microcontroller's input with internal 50kOhm pullup resistor. simulate this circuit – Schematic created using CircuitLab ...
3
votes
2answers
79 views

CMOS 4066 Question

This is my first post here and I have a question about a CMOS circuit I have been designing for I while using the 4066 (I'm a noob to digital electronics). I am using a 4066 to pass random pulses I ...
1
vote
1answer
215 views

Reading noise from allan variance plot for MEMS sensor per IEEE Std 952-1997

I am following the Standard Sensor Performance Parameters from the "MemsIndustryGroup" to test some Gyroscopes: I conducted a test and plotted the square root of AVAR (Allan Deviation) against Time ...
0
votes
4answers
90 views

MOSFET gate grouding via LED - noise

simulate this circuit – Schematic created using CircuitLab I use D1 to visually indicate the active transistor. However, gate pin acts as if it were floating. What is wrong with my ...
2
votes
1answer
98 views

Ground noise measured on scope

I've connected a scope probe directly to the ground clip of the scope. I then observe the signal on the scope and it's reading 0, as expected. I set my trigger to be 1V above the 0V reading it ...
1
vote
1answer
87 views

Thermal Johnson-Nyquist Noise Generator

I have no background in electrical engineering so please bear with me. I want to create a random number generator/displayer using a resistor. My idea is to wire a resistor to an amplifier of some ...
1
vote
0answers
118 views

USB battery charger noise in an audio amplifier

As the title says, I'm having some issues with battery charger noise and an audio amplifier. The PCB with the charger and amplifier is connected to a GSM device, and that's where the audio signal for ...
1
vote
1answer
61 views

Thermocouple on a grounded stainless steel box

My present project is a ~6kW switching converter in a sealed stainless steel box. The box is grounded well. When I put a thermocouple on the surface of the box, the reading is noisy. Even if I put ...
0
votes
2answers
56 views

Sporadic Clock Signals from Momentary Switch

I'm having trouble using a NO momentary switch to send clock edges to a J-Kbar flip flop, specifically the TI CD74AC109E(datasheet). I have a switch between +5V and the clock pin, and also added a ...
18
votes
2answers
1k views

Why does connecting a high-current device to my digital circuit cause weird behavior?

I have a arduino microcontroller other digital thing and when I connect a motor pump heater other high current thing I experience weird ADC measurements reboots crashes errors in digital ...
2
votes
2answers
113 views

noise caused by square wave signal

I am using electronic switches to create non-TTL square wave clocking. The oscilloscope graph demonstrates two measurements: Yellow signal: 0-8V Blue signal: 0-5V As you can see, yellow signal is ...
2
votes
2answers
175 views

Reduce gear box and DC motor noise

I'm working on a project where I use DC motor and gearbox to reduce the speed and get a higher torque. The problem is, when the project sit, for example on a table, the noise is amplified. (with ...