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Questions tagged [noise]

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

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Digital 3.3V switching distances <10m

I would like to know what is a reliable way of sending digital signals over about 5m using a 4 core cable. I don't care for isolation as the micro is only 3 bucks but I know that at these distances ...
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1answer
72 views

Amplifier Noisy Output (LA4597)

I have a problem with my amplifier circuit (LA4597). I tested it (12V). It turns on and the speakers and fine and silent. But when I try to add an audio source (RCA) within the circuit, the speakers ...
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1answer
43 views

Equivalent noise resistance(s) - 2 stage amplifier

I came across this question in my textbook: The first stage of a 2-stage amplifier has a voltage gain of \$150\$, an input resistance of \$1500 \Omega\$, an equivalent noise resistance of \$700 ...
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34 views

What could be the source of this noise?

Below is the output of an accelerometer when it is standing still: The zoomed 0.5 seconds of time series voltage data above is from a 4 seconds of measurement with a data acquisition board at 30kHz ...
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2answers
38 views

Amplifier Specifications for Lock-in Detection

Since a lock-in amplifier is effectively a high-precision AM demodulator, what are the most critical characteristics for amplifiers in the high-frequency signal chain? Take a 50kHz lock-in circuit for ...
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2answers
73 views

10 mV spikes in adc readings

I have a custom data logger attached to a sensor being powered by a solar panel(charge controller and battery). I have a problem where I'm getting 10 milliVolt one sided spikes in my ADC readings as ...
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1answer
55 views

Common mode chokes in series

I am designing an ultralow noise audio board. On the first PSU PCB (just talking after bridge) I have a CMC to remove switching noise on diodes to undetectable levels (with plenty of capacitance for ...
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1answer
50 views

High voltage to low voltage buck converter for(60V IN 5V 3A out) making noises?

I've been trying to convert a high voltage input to a lower voltage (5V at around 3A) with no luck using these Modules and all of the LM2596HV iteretions of modules out there and all seem to make ...
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2answers
52 views

Calculating the frequency of data lines?

I read a calculation about determining the bandwidth of USB https://www.edn.com/electronics-blogs/all-aboard-/4425691/Rule-of-Thumb--2--Signal-bandwidth-from-clock-frequency Roughly what was said is: ...
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40 views

Upstairs circuit in house is noisy [migrated]

first of all, I'm sorry if I'm posting in the wrong community. I looked for a stack community more related to my issue but couldn't find one. Here's my issue: all the outlets on the 2nd story of my ...
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18 views

Finding output SNR using Noise figure

am trying to solve this question below: So I did find the system's overall noise figure to be 2.3 = 3.68dB, and you are more than welcome to verify it. However, my problem now is to find the output ...
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1answer
60 views

Dealing with coupling of PWM noise into Hall-Sensors as spikes in BLDC driver circuit

I have designed the first revision of a BLDC driver board (based on STM32 and DRV8323 chips). Right out of the bath (after writing the firmware of course) I noticed that the coupling of PWM into the ...
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1answer
47 views

GSM Interference with Meanwell Switch mode PSU

I am having trouble with interference from a GSM modem and my switch mode PSU. I do not know much about interference and how the radiation patterns works for GSM. Below is an image of the circuit ...
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2answers
36 views

Replacement of MEMS gyroscope with better less noise devices [closed]

Is there any good replacement for MEMS based 6 or 9 degree of freedom gyroscope to use with Arduino ? I read that most of MEMS are not reliable regarding the values, with slow reading and high noise ...
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3answers
88 views

Using shielded audio cable for potentiometer sensor

I'm trying to measure a potentiometer from an Arduino's ADC. The potentiometer has a maximum value of 100k ohms and is located about 1 meter from the Arduino. The potentiometer's wiper is wired to the ...
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1answer
95 views

Bad 100Hz ripple in linear regulator circuit

Background I'm a beginner trying to make a linear regulator and made some decent progress on a breadboard powering from a 20V laptop charger. After battling off the typical opamp instability issues I ...
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2answers
85 views

Why isn’t thermal noise work possible?

This must be an absolute naive question, but I’m going to ask it anyway. Aside from the obvious thermodynamic law violation, if I short cut a resistor’s terminals, why doesn’t thermal Nyquist noise in ...
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2answers
99 views

Reducing noise on a voltage reference

I need a stable, low noise voltage reference that I can adjust between 1.4V and 1.8V. The output should source or sink up to 0.25mA @150Hz max. The output will provide a +1.65V bias for a bipolar ...
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2answers
109 views

How to amplify a low Amplitude, High frequency signal from Ultrasonic Transducer?

I am working with some ultrasonic transducers, the receiver gets a signal of around 10 mVp-p at 125 kHz and for its purpose needs a gain of around 10. So far have a simple inverting OP-Amp setup, ...
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2answers
310 views

How does the differential cap at the input to an ADC/amplifier help reduce noise?

I often see differential amplifiers/ADCs with a conditioning circuit that looks like this: I'm trying to figure out how Cdiff helps reduce noise/improve things. So far as I can figure out it's ...
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1answer
67 views

Loudspeaker / Amplifier “POPP” sound [closed]

I have different sound systems here. Some of them share the "problem" that they make a "popp" sound when I switch them on or off using the front-panel switch. If I accidentally switch off the socket ...
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40 views

How to do switching noise analysis of dcdc on LTSpice

Background : In one of my board i have used LT8471 as DCDC , as my cards being analog cards, i tried maximum to seperate the power network and analog chain from noise, my initial problems with dc-dc ...
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2answers
148 views

DC-DC switching converter PCB design

Recently I had a problem with noises in my led driver. I realized that my PCB design was terrible, so I redesigned whole PCB following common rules. Could you take a look and check if my new design ...
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2answers
26 views

How to implement sealed line noise-proof method in this circuit?

I am trying to generate -8.5V from my 5V battery. I found a suitable IC for my purposes. The datasheet of the IC (circuit schematic is available below) says use sealed line noise proof method (...
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1answer
20 views

Netfilter (230VAC) without protective earth (PE)

I need to filter my mains input, but I don't have any protective earth (PE). Will a mainsfilter (schaffner for example) still be usefull? I think so. I think the mains filter despite of not being ...
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1answer
50 views

Conversion of Additive Noise to Phase Noise

RF Microelectronics by Razavi contains the following snippet in section 8.7.3 concerning the analysis of phase noise in oscillators: We write \$x(t)=A\cos(\omega_0t)+n(t)\$ where \$n(t)\$ denotes ...
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4answers
121 views

How do I measure very low frequency noise?

I'd like to measure low-level noise in the 1 Hz to 100 kHz range, for example at the output of a LDO. For higher frequencies a spectrum analyzer would do the job, but most only go down to the MHz ...
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0answers
44 views

strong noise in microphone unless usb receptacle is grounded

I installed a Banana Pro (like Raspberry Pi), plugged an usb audio stick in, and a microphone in it. I run this thing with a properly dimensioned usb power supply (tried different ones). This way, ...
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1answer
78 views

How to route a nasty signal (200V/µs)?

I have to route this signal for a distance of ~70mm† through a dense (mostly digital) 2-sided board. The signal is generated externally and I have no control over its shape, it's basically a pulse ...
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4answers
113 views

Does reactance increase noise?

Impedance is made of resistance and reactance which is capacitance and inductance. I read that increasing resistance increases noise, but what if capacitance or inductance is increased, does the noise ...
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2answers
328 views

What's the cheapest way to make a dithered-input ADC?

I know that some of these PICs have ADCs built in, and I may want to use that. I am wondering if there is a way I can effectively dither the input to a low-bit (like 8 bits) ADC with the fewest parts ...
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1answer
85 views

Which design to choose for highly stable LED or laser diode driver?

I'm looking at several design choices for driving a LED and/or laser diode in a very stable, low noise way. The specs are as follows: current: 1-100mA, adjustable (the adjustment can be either ...
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1answer
49 views

How to reduce noise in this circuit?

I'm using a Raspberry Pi in a circuit I'm building that includes a few elements. Elements in the circuit: PWM driver to control 3 servos Mic board for recording Class D Amplifier that drives 2x3W ...
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2answers
50 views

Phase noise in spectrum analyzers

I'm reading about spectrum analyzers from Keysight's AN 150 and I have two questions regarding phase noise. The AN states: No oscillator is perfectly stable. Even though we may not be able to see ...
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4answers
71 views

Voltage Dividers for a beginner (with respect to soil moisture sensors)

I've just started with electronics and want to make an analogue soil moisture sensor (with Arduino). When I looked online for an explanation of the working, every site said that it works as a voltage ...
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1answer
69 views

Canceling ambient sound [closed]

I've just moved into a new flat and I noticed that there is a lot of car noise coming through windows. I know, I could just close the windows, but that's a less interesting approach to a problem. So ...
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64 views

UART noise on A6 GSM module

I'm using the A6 GSM module to send data from my sensors board to a server via GPRS. The problem is that most of times, usually when the module attaches to the network or connects to the server, ...
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1answer
62 views

Eleminating radiation from chargers

When I move my EMF radiation meter near a charger it shows me that there is radiation from the charger, and even the device itself radiates when the charger is connected to it. The chargers emit ...
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1answer
36 views

Bluetooth audio circuit noise problem

I am working with a bluetooth audio circuit. I am facing noise problems in the mic input so I used B0505S DC DC isolated module. It worked but now when I printed a PCB of the same circuit and I am ...
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0answers
32 views

Is this SNR change related to aliased common mode noise or some other phenomenon?

Below time series offset value of a force transducer amplifier which is sampled by a 16-bit single ended earth grounded data-acquisition board at 500Hz (red plot) and 12kHz (green plot). Before I was ...
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2answers
427 views

Why is this the maximum dynamic range in a spectrum analyzer?

In Keysight's popular AN 150 there is a plot of noise and harmonics amplitudes versus the level of the input signal at the mixer (page 57). It's stated there that the maximum n-th dynamic range is ...
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1answer
46 views

Effects of increasing current on external noise and SNR for analog transmission

This is a conceptual question about long analog signal transmission exposed to capacitive coupling and EMI noise as shown in below figures: simulate this circuit – Schematic created using ...
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103 views

Where exactly in the environment does the 60Hz power line noise be picked up from?

I am measuring EMG signals using ADS1299, and I have problems removing/eliminating the 60Hz noise in my measurements. I measured the EMG signal in differential mode, and I also incorporated a driven ...
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200 views

How to avoid noise in YHDC SCT-013-000 current transformer?

I have a SCT-013-000 current transformer which I have connected to Arduino Uno with a burden resistor of 33 ohms and the calibration value I am using is 60. The problem is we are getting current ...
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2answers
73 views

What can be said about the nature of the noise by looking at this spectrum?

I use some industrial amplifier modules where each of them amplifies force transducers. All amplifiers are powered by a single power supply and the output. Amplifier is set to 6kHz filter. And there ...
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1answer
72 views

Noise problems in current sensing

I have the following circuit: simulate this circuit – Schematic created using CircuitLab I am using a motor from an electric bike, as a generator and I am rotating it using a drill, to test ...
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0answers
85 views

Induced power supply noise on switch contact

I have a circuit that has a 24V section and a 5V section, separated by opto-isolators and an isolated DCDC converter. Both sides of the DC-DC have decoupling caps, and the MCU has one per Vcc pin. ...
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2answers
48 views

Trying to couple some noise

My problem is easy to explain. I want to couple/add some Noise into 240V 50Hz. For this purpose, I have a Noise Generator which is triggered manually with a signal processed by a microcontroller. I ...
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1answer
138 views

Electrical noise resets & chattering in relay modules using ESP8266

I am trying to build my own SONOFF like device by using a Wemos D1 mini and associated circuitry. I am facing an issue with electrical noise where whenever switching of the relay causes chattering ...
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1answer
56 views

Design/Purchase a Filter for Data Acquisition System

We have several types of data acquisition devices where I work. They're used primarily to measure low frequency voltages (<100HZ, +/-10V). One device has a built in filter that does an excellent ...