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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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17 views

Allowing different inputs without needing to alter gain every time; a situation for a pre-amp?

The goal I am attempting to make a small diy bookshelf speaker system using 2 16ohm, 25 watt speakers and a 2x25 watt class d amplifier board. If it matters, the amplifier board is a class d amplifier....
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20 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 ...
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0answers
15 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 ...
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1answer
94 views

Making noise on a wire

For some educational purpose I want to make some noises on breadboard wires but they barely become noisy , I'd transfer my data with 5v electrical potential on 50cm wire length, I tried multiple ...
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27 views

noise in ISD4003

I need to record voice in an ISD4003. Using the audio input with a condenser mic isn't sensitive enough. I added a 1 transistor preamp which works well but it now introduces a ticking noise. I believe ...
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6answers
3k views

Is it necessary to separate DC power cables and data cables?

I have had this discussion with my colleague earlier. A DC power supply is non-alternating, so the magnetic field a DC power wire generates is constant (is it?). Now, I know the rule is to separate ...
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1answer
42 views

How to create EMI/EMC noise for testing product behavior in noise environment?

We have product which works on three phase AC supply. We were facing issue on I2C interface of external RTC due to noise from external environment. After some inspection, we realized that because of ...
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1answer
59 views

Maximum Allowable Noise of ADC Input Signal

I have a question about calculating the maximum allowable noise for an ADC signal conditioning stage. I have an existing signal conditioning stage as well as an ADC on a microcontroller. I would ...
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2answers
42 views

What is meant by counts of noise in this context?

Regarding the following paragraph about resolution of a 16-bit ADC: Unfortunately, other factors enter the equation to diminish the theoretical number of bits that can be used, such as noise. A ...
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1answer
111 views

Shaping ground plane on a 4 layer USB Midi controller PCB

I have asked about this before but I have to admit that I didn't read enough before asking and therefore was'nt able to ask the question properly. I hope I am now. I'm designing a 4 layer board with ...
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1answer
28 views

Noise canceling while recording from mobile on PC

I have a setup in which I have to control mobile Android device from the PC and record the outgoing sounds of it. The control is done by a USB cable. For audio recording I use a headphones which I ...
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1answer
39 views

Increase voltage drop required to saturate PNP BJT to avoid noise

I have this circuit which must signal +3.3V or 0V depending on the switch status. The the switch is about 20 meters away and is getting EMI from mains. I realized that it only takes -0.7V of ...
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1answer
29 views

How much does the Bias Voltage affect the NEP of a photodiode?

Look at this data sheet for example. Everything there is measured at 0V, including the NEP, if I connect that photodiode in reverse bias, how will that NEP change?. I'm inclined to believe that it ...
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1answer
58 views

Best way to isolate a white noise source from the rest of my circuit?

I have an acoustic project that self-calibrates every so often by playing white noise and doing some processing on it. My white noise source circuit is below. My plan is to direct the white noise ...
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1answer
35 views

Ground Audio channels when mute

I'm using a PCM5102A DAC in a project and I've noticed that when the IC goes to sleep (>1 second without data on the I2S bus) there is some errant switching noise audible via the amp. If I connect ...
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0answers
33 views

Switching regulator high frequency ripple

I've built a switching power supply with a TI 16006Y IC. It seems to be doing its job correctly however I'm having trouble getting rid of the high frequency ripple that occurs for a short period every ...
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0answers
90 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 ...
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3answers
162 views

32.768kHz crystal making audible noise

I am doing a project to record and log the voltages of an 8 cell lithium battery. The project is based on an STM32 microcontroller, and logging is done on an SD card. I have made the first version of ...
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2answers
64 views

Emitter-coupled logic operation

For the operation of emitter-coupled logic and sedra smith book, 1) Compared to CMOS, why ECL is the faster logic family given that it requires so many transistors to propagate to output Y (T5 ...
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2answers
127 views

Reducing noise in this audio amplifier

Here is a picture of a circuit I built. I'm a novice in building amplifiers, but I'm interested in building a simple circuit that picks up music using a condenser microphone and transmits it across ...
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1answer
61 views

LTC3106 - getting 3.26v instead of 3.3v

We designed a power supply for an iOT. The uses SoCl2 battery and solar panel combination. The circuit is functioning and we are getting 3.26v consistently for over 3 days now. LTC3106 is configured ...
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1answer
65 views

Why does RCA Splitter add noise in output

I have used an RCA splitter (one female input split to two female outputs) to split the Set Top Box (STB) (Satellite TV) output. One goes to TV while other goes to AV capture card on my PC. With this ...
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1answer
54 views

Noise quantification from sampled data

If a sampled voltage signal \$y[n]\$ is composed of its offset \$\bar y\$ plus noise \$x[n]\$; i.e. \$y[n] = \bar y + x[n]\$, are both following equations for the RMS value of the noise component \$\...
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3answers
85 views

A question about measuring white noise in practice

I have some confusion about practical aspects of dealing with white noise. Let's say you want to quantify or view the white noise component of a power supply output or a constant transducer output. ...
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3answers
68 views

How is companding different from pre-emphasis and de-emphasis?

What I know is that interference increases linearly with frequency and thus noise power is concentrated at higher frequency. So, to reduce noise, pre-emphasis and de-emphasis filters are used which ...
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2answers
100 views

How much power can electrical noise (EMI) produce?

I have a 5-meter-long wire connected to an ESP8266 input. The wire is connected to a regular wall-mounted switch and goes through my room's wall and is adjacent to mains power lines. As you would ...
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1answer
59 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 ...
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1answer
50 views

How to use my bits to transmit this photodiode signal in the most efficient way possible? [closed]

Suppose I have photodiode with a Dark Current of 5 pA and that using the NEP of that photodiode at some frequency \$\lambda\$ I determined that the smallest signal I could detect was of 1 pA. First ...
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1answer
52 views

Heaphone amplifier PSU noise

I built myself a headphone amplifier using the LM49600 and a PGA2310 for volume control. This part of the circuit is fairly standard and I don't think it's the problem. I wanted it to be powered by a ...
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1answer
93 views

Problem in temperature transmitter because of VFD (Variable Frequency Drive)

I made an amplifier of PT100 bridge which operates on 24V DC supply and gives 0 - 10V DC for 0 - 400°C when tuned. The circuit is as follows : Here P2 + and P4 S+ are shorted and P4 S- is left open....
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0answers
42 views

What is the point of the zero ohm resistor between LED_VCC and VCC_3V3?

I am designing a IR sensor transimpedance amplifier circuit based off of the Texas Instruments Particle Sensor (TIDA-00378). Between the separate power buses (LED,TIA,VCC) there is a connection with a ...
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0answers
99 views

How can I get this circuit to “make noise”

I designed this noise generator circuit that uses a 1N514 Schottky diode with a VDB transistor amplifier(note: the upper VDB resistor is actually 15kOhm). Looking at the oscilloscope trace it seems to ...
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0answers
48 views

Origin of increased noise in BF862/OP27 charge amplifier

For the amplification of piezoelectric sensor signals I am currently building a charge amplifier with a low noise JFET frontend utilizing an NXP BF862. The amplifier design is based on application ...
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5answers
130 views

Please explain this formula for the relationship between bandwidth and the temporal response of a photodetector

I am reading "Optoelectronic Sensors" by Didier Decoster and Joseph Harari. At section 1.8.2 they start explaining the relationship between rise time and bandwidth, and they give a very weird formula ...
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1answer
80 views

Eliminating ADC Noise

Im currently using STM32F4'S built in 12 bit ADC. When I get my measures, it varies wildly at +- 40 numeric range. Is there a way to eliminate this? I have tried software filtering with no luck. ...
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0answers
43 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
83 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 ...
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1answer
32 views

dual rail DC/DC convertor and CMC

I have a DC/DC convertor that tales 5V and makes + 15V and -15V rails My question is how to place common mode chokes to reduce common mode noise. Should I place 3 of them (1 on the negative to Gnd , ...
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2answers
145 views

Shot or thermal noise of a MOS transistor

I'm trying to compare the shot and thermal noise contributions in a MOS transistor. In the literature, the above-threshold MOS transistor has only thermal noise, which is found by integrating the ...
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0answers
57 views

Estimate minimum detectable light pulse in a photodiode (5 ms, 44 kHz modulated)?

I'll use an IR LED modulated at 44 kHz to illuminate particles in air or water, and will use a silicon photodiode to detect weak pulses of scattered light as they pass through the LED's collimated ...
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2answers
111 views

Ferrite bead in Ground path of Input Power Supply

I have been following the schematics of Colibri Toradex Carrer Board. I have used most of the components from their design. However, they have used ferrite beads in Positive terminal and Ground ...
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2answers
43 views

Isolating A Noisy Component In A Circuit

I've been working on a project the past couple months or so and I am incorporating an lcd touch screen as an interface for it. The device is a small digital synthesizer. The problem I am having is ...
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1answer
79 views

Noise on my oscilloscope when probing a wire

I am prototyping a NTC voltage divider circuit and I am having trouble with noise on my probe. It seems like I am constantly getting a large amount of noise (200-300mv) on my oscilloscope waveform ...
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1answer
50 views

Crosstalk between AC and DC

First time asking a question but I've come across something I just can't find the answer to. Whether or not it's because a silly question I hope to find out. So I understand that with crosstalk ...
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0answers
57 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: https://power.murata.com/data/power/ncl/kdc_nmv.pdf The problem is they introduce so much switching noise. I try ...
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1answer
31 views

Initial noise prior to square pulse

I have a high voltage system (~5kV) to generate pulsed spark. I was able to detect the spark ignition. It has been shown in the images by the yellow line. This signal will be used to generate another ...
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2answers
85 views

Ferrite bead for high-speed digital IC

Although I've seen numerous recommendations for the use of FBs on the power supply rails of noise-sensitive analog circuitry, the opinions regarding their use with high-speed digital circuitry are ...
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1answer
69 views

Connecting bandpass filter to comparator generating excess noise

I have a band pass filter with a center frequency of 100kHz, a bandwidth of 10kHz, and a gain close to 1. Input signal is 100mV-150mV peak to peak with frequencies varying from 80kHz to 120kHz. I am ...
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2answers
154 views

How can I remove 1.4MHz and 150kHz switching noise?

(Please excuse my English) I have two types of DC-DC step-down(buck) converter modules, and the switching frequencies of the converter modules are 1.4MHz and 150kHz each. The two converter modules ...
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0answers
26 views

Unwanted buzzing and reduced volume in a basic speaker set

I have the following device, which basically contains 18 songs. we can play the next song by switching the switch on and off. It also has a volume control. Recently it started to buzz a lot and the ...