Questions tagged [noise]

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

175 questions with no upvoted or accepted answers
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2answers
138 views

How to reduce an audio system noise in a way which is similar to a human touching one of the system's components?

I have a somewhat weird question (hopefully not too weird). I work with an audio system. It includes a wave generator, a (33500B series Keysight) wave generator, an amplifier (2003 op-amp based ...
5
votes
1answer
187 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. ...
5
votes
2answers
164 views

Which is the preferred approach to PCB layout for signal vs power traces in analog circuits, and things to consider?

I have had to layout 2 layer PCBs several times now for analog signals, and am just beginning to learn the process. I often face a similar question in one form or another with regard to laying out ...
3
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0answers
55 views

Photon count with ADC, am I doing it right?

I have this LED and I want to characterize this photodiode. The LED should produce light of 370 nm, but I measured it and it is around 358 nm, and at that wavelength the quantum efficiency (\$\eta\$) ...
3
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0answers
50 views

Differentiator circuit sees noise on PCB after 2 min

I'm new to PCB design, and looking for some advice. I designed a PCB shield and I'm seeing a lot of noise in my differentiator circuit. The circuit will run perfectly for about 2 min and then all of ...
3
votes
1answer
83 views

Headphone Noise from Laptop SMPS

I have been facing an issue that has been a mystery to me for quite some time, and I wanted to see if someone here can potentially give me more insights on this so I can understand why it is happening....
3
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0answers
143 views

ADC conversion value spike during ADC conversion

Description of the situation I am trying to get an analog vibration sensor signal to a Raspberry Pi 3 B+. To convert the analog signal to digital values, I'm using Waveshare High-Precision AD/DA ...
3
votes
1answer
109 views

What effect does a logic analyzer probe have on a circuit?

I have an MCU controlling a LED sign. This sign speaks the HUB75 protocol, which is essentially a large shift register. Being a shift register, this requires a clock signal to be generated, which the ...
3
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0answers
78 views

What is the signal-noise model of laser induced fluorescence?

The following image is an example of a fluorescence signal trace from the photomultiplier tube detector (PMT). Each spike represents one fluorescently labeled cell. This signal model is definitely ...
2
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0answers
57 views

How to remove DC power supply noise while load is active?

I'm using a breadboard power supply to power up two STM32F103, two Hall flow sensors, one IC555, and one 16x2 LCD with backlight. While everything is connected I have alot of noise in the system which ...
2
votes
1answer
59 views

Noise for a switched capacitor circuit

I have a switched capacitor circuit that looks like below: It operates at 80MHz to realize a 625k resistor. It works fine in the circuit. I tested with VDAC(input)=1.8V and the voltage at the right ...
2
votes
1answer
55 views

What is the relationship between dark current and the contribution of dark noise in a photodiode?

For example, if I have a datasheet for a photodiode that lists a dark current of 1000nA. I have a transimpedance amplifier with 1kohm transimpedance and 1 mV voltage output voltage noise. Presumably ...
2
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0answers
37 views

SMPS mains hum on guitar rig

My guitar rig consists of Guitar -> Audio Interface (Steinberg UR22) -> Laptop (via USB). I listen to the (processed) audio using headphones connected to the audio interface. ISSUE: When the ...
2
votes
1answer
123 views

Signal noise cancelled by touching the leads

I have a pressure sensor that outputs 0.5V with a +/- 20 mV noise. I am trying to identify the root cause of the noise using an oscilloscope. The noise occurs in waves of twice the mains frequency, ...
2
votes
1answer
101 views

Questions about a design for an SMPS post regulator filter circuit?

For minimizing SMPS ripple and especially noise, I’m trying to make a small interface which is a post regulator cascaded after an LC filter. I have come across some papers related to this topic and ...
2
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0answers
64 views

Noise immunity of single ended analog voltage signal

I want to use a sensor with analog output in my design. The output of the sensor is a low frequency traingular wave (less than 300 Hz) and voltage vetween 0 - 5V. I need to carry the sensor signal to ...
2
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0answers
76 views

What is the reason for high frequency noise when amplifier is powered with battery?

Hi I made a small headphone amp and powered it using lipo battery.voltage is stepped up to 5v.everything is working with direct supply (ie., while charging battery)but as soon as I unplug the charger ,...
2
votes
1answer
422 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 ...
2
votes
1answer
55 views

IR emmiter and reciever layouts for custom sensor

I'm having a hard time designing a PCB for a sensor array that need to detect if there is a small reflective object (3-20 mm section) in the way. That object can slowly rotate around a shaft. I have ...
2
votes
3answers
1k views

Controlling PWM noise on power supply

I've got a problem I haven't been able to sort out experimentally and am looking for help from someone who knows more than me. I'm making a handheld prop with audio and lighting effects. In the past ...
2
votes
1answer
177 views

How to reduce the effect of electric lighter noise on Micro controller?

I am using a kind of electric lighter in my circuit in order to turn the fire on. And also i have used some sensors that alert in danger by sending a signal to the MCU (ATmega 32) interrupt. The ...
2
votes
0answers
494 views

Modded speakers emit high frequency noise, how to filter it out?

I came up with an idea to convert my PC speakers into Bluetooth speakers. It's not really a serious project, rather a proof of concept, but I want to get it to work as well as possible. Here's my ...
2
votes
1answer
265 views

SMPS output noise: Why is it amplified further away from the output capacitor?

Well this is just a general question about switch mode power supplies, but i have recently built a buck converter, and read that it is very important where in the circuit you place your probes, to ...
2
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0answers
531 views

RS485 ground noise problem

I'm using the USB FTDI dongle to convert USB to RS485, half duplex, 3 wires (A+, B-, GND) with 115200 baud rate. I'm working with controller of NXP (K64) and I'm experiencing random tx enables on the ...
2
votes
1answer
126 views

Noise in FET reverse-polarity protection for ADC

I have quite precise ADC circuit. I want to protect input supply voltage (not ADC input) from reverse-polarity using FET transistor as shown on the picture below. I wonder: is there any noise / worse ...
2
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0answers
163 views

How does this diode improve the common mode conducted noise?

This image was taken from UCC28881 (page 16) The desciption in the body says: A half-wave rectifier is chosen and implemented by diode D2 (1N4937). It is a general purpose 1-A, 600-V rated diode....
2
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0answers
479 views

What's necessary to properly decouple/filter a PWM-controlled fan from an Arduino?

I've got a small problem I could use some help with. I am using an Arduino to control a cooling system I am building for a DSLR. Primary goals are to use PWM and some pots to control TEC power, as ...
2
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0answers
140 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 \$systemVariable(t)\$...
2
votes
1answer
63 views

Relay+SMPS = Noise in RS-485 bus

I designed a board with a microcontroller (Atmega328), 3 relays and a RS485 transceiver. The relays control SMPS LED drivers (Meanwell LPF series). The system consists of 10 boards, each one ...
1
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0answers
29 views

Need help troubleshooting Teensy 3.6 SPI to DAC8568

running out of things to check with this problem I'm having. I designed a board around the Teensy 3.6 microprocessor, and I wanted to connect a DAC8568 chip to it for some analog outputs. It works ...
1
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0answers
42 views

Phase noise of a digital PLL

I assume the reader is aware of how a DPLL works. The DPLL oscillates with a frequency of \$F_{out}\$. The DCO free running frequency is \$F_{free}\$. In the model of our DPLL we've only considered ...
1
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0answers
26 views

How to reduce noise for arduino capacitive sensing

I have an artistically-painted 5mm-thick wood panel that I want to use as a light switch without alteration to the image. My solution was to (try to) make a specific region on the panel touch-...
1
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0answers
104 views

RC filter for UART

I am working with a device. Block diagram looks like this: I was facing a noise challenge and asked a question here. I implemented the RC filter design suggested by @analogsystemsrf and got good ...
1
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1answer
75 views

Is there a standardised noise source symbol for circuit diagrams?

Does anyone know of any standard symbol for a noise source, for example of one wants to represent the Johnson-Nyquist noise, what is best to use?
1
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2answers
94 views

Design Considerations for comparator with ~1mV accuracy?

I am working on building an "exploded" analog to digital converter (ADC) (tracking type: up-down counting) for teaching purposes. I am working with a 0-5V reference, and 12-bits of precision (values ...
1
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0answers
44 views

1V Overshoot and Undershoot on Power Rails of LTE Module

I have designed a PCB (four layer) having SIM7600I LTE Module. The Stackup is: Signal & Component Layer with Ground Pour Internal Ground Power Plane Internal ...
1
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0answers
27 views

Using a switching DC-DC converter in high dynamic range current/voltage sensing

I'm thinking of making a power meter circuit which will have a high-side current-sensing amp (LTC6102), a resistive voltage divider for sensing the voltage, a dual op-amp (OPA2365) as a buffer for the ...
1
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0answers
123 views

How to make a guitar amp switcher?

So I'm trying to build a guitar amp switcher (and I don't really know what I'm doing =)). The idea is that guitar out is connected to X4 jack and then switched to either X1, X2 or X3 jack, which ...
1
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0answers
82 views

What factors cause the harmonic distortion in ADC at high signal amplitudes?

I have been studying about the ADC's SNR vs amplitude relation. A sample curve is shown below: I am interested in the region rounded (orange) of the gray curve. At that region, we expect to see ...
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0answers
103 views

Noise floor raising at high RF input power after filtering

I have a USRP b205mini with AD9364 transceiver. When it receives a very high RX input of about -5 dBm at different frequencies, not in the original RX range, the noise level raises slightly. The RX is ...
1
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1answer
94 views

How do I get rid of switching noise from these types of DCDC converters?

I am using a lot of these types of isolated DCDC converters for measurement circuits. The problem is they introduce so much switching noise. I try to put filters on the output and even put the ...
1
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1answer
119 views

Reduce Noise Added With Zener Clipper

I'm working on a hobby Arduino project to create an audio visualizer using an LED strip. I'm using the MSGEQ7 to separate the signal into 7 bands, then send it to a Wemos D1 Mini. I started by ...
1
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0answers
119 views

STM32F4 ADC oscillating

I am trying to read the ADC of a STM32F4. The code skeleton was generated by CubeMX, the HAL library is used. The read values are feasible but have periodic noise, as seen here: The plot was ...
1
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0answers
70 views

Gyroscope drift in IMU

So, a brief foreword. I'm not sure if this question belongs here or in the DSP community, its closely related to both, but I have a feeling this will be more of interest here nonetheless, so I am ...
1
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0answers
31 views

Noise on Input Buttons for H-Bridge

I'm constructing an H-Bridge to control a linear actuator. I've done so by using a 2-channel relay module, some buttons, and a ESP32. I do not believe this is an issue of debouncing as I account for ...
1
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0answers
103 views

Identifying Noise in 12AU7 Based Headphone Amplifier

I've been working on making a tube based headphone amplifier as a fun personal project. The amplifier is based around this 12AU7 vacuum tube. The project for the most part is following this existing ...
1
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3answers
78 views

Inherent DC Bias in ADC sampling

I was just simulating the quantization behavior of ADCs of different bits, on data sampled by a 24-bit ADC. What I noticed that as we go towards ADCs with less bits a DC bias in the signal becomes ...
1
vote
1answer
103 views

Good PCB Design - Single Power Plane with 2 Power supplies (+ve & -ve)

Recently I've taken over a project which requires low noise but the design given to myself does not meet the requirements. I noticed on the PCB design It has a single Power Plane with 2 separate ...
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0answers
69 views

MEMS Microphone noise floor power level & audio noise spikes measurement

I have a circuit with a MEMS microphone and would like to be able to measure the audio noise spike contents and check the noise floor power level in the audio circuit. My intention is to connect the ...
1
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0answers
52 views

How to calculate circuit noise in dB from measurement

I've never quite understood how to calculate the noise in dB from an analog circuit at the output of the ADC. This is my measurement: It is a 16bit ADC, as we can see there is roughly a +/-1 bit, or ...