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

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20 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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49 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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2answers
46 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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35 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 ...
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1answer
109 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
33 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 ...
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1answer
59 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): ...
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1answer
54 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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64 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 ...
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1answer
58 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
64 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
63 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 ...
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2answers
74 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
47 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
42 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
48 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
111 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, ...
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1answer
38 views

What current values are prone to noise?

I'm using voltage dividers to drop down from high voltages like 327V peak to 2.5V peak and read it with an ADC. (Also reading lower voltages like 5V from various sources, so the above was just an ...
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1answer
77 views

Reducing signal noise arduino to simulink analog read

I'm using an op amp to amplify the input of a pressure sensor from milli volt to volts using with arduino. Both the amp and the sensor are externally powered using a DC power supply. I'm trying to ...
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68 views

Generating very low noise control voltage from an MCU?

I want to control the THAT Corp. 2180 VCA using an MCU. I'm using the positive VC input (it has one positive and one negative and they are symmetrical). The range that I want to generate is +/-540mV. ...
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63 views

ADS1278 Noise level

I have been using ADS1278 TI ADC, after I made the digital side work with my processor, I shorted the + and - of the analog input for a channel to check the noise (used recommended capacitors for ...
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1answer
62 views

Fixing a noisy I2C bus

I'm trying to get an I2C bus working but there's a ton of noise and I don't really know what's causing it. The circuit is pretty simple, an ITG-3200 and an Arduino DUE. Here is the problem: As you ...
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1answer
62 views

Low Noise Using Opamp And Photodiode?

I'm building a small sensor setup that is able to measure the transmission of light through a (clouded) solution. I currently have a laser light that shines through the solution and a LDR on the ...
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2answers
158 views

Circuit Implementation of Dynamical Systems - Lorenz Equations (Failure Analysis)

Let me begin with the disclaimer: I am a mathematician and not an electrical engineer. That being said, surely I am missing something simple. For classroom demonstrations in dynamical systems, I have ...
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45 views

Inverter noise picked up on USB data lines breaks USB communication - signal integrity

I have an equipment where the CPU is a 16-bit dsPIC. There is an inverter board switching 300V across a 4 MOSFETS H-bridge at 20kHz and delivering 180W. This equipment communicates with a computer ...
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29 views

Reducing noise from an input using an FIR in VHDL

I have a non digital input I want to read in my VHDL file but it has sooo much noise that I would like to filter out using a digital filter that would sample the signal and allow pulse levels that ...
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22 views

RIN measurement of CW laser

Right now Im doing an RIN measurement of a CW Raman fiber laser. In theory, Im supposed to see a relaxation oscillation which manifests as a single peak in the trace. What if I can't detect the ...
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41 views

How much the noise of this circuit?

I have a circuit like this. From the data sheet of the Op Amp I know that it has voltage noise $$e_n=0.85\frac{\text{nV}}{\sqrt{\text{Hz}}}$$ and electric noise ...
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2answers
64 views

Placing electricity, cable, phone and internet transmission lines tight together

Will this cause noise in the phone and internet signal? also placing them through concrete with absolutely no air space around them. This is happening in one of my friends house, he has issues with ...
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2answers
73 views

Electronic compass, RF and batteries

I am currently working with a project where i am creating a small embedded board consisting of a 9DoF IMU which is transmitting its data with RF (BLE or normal RF). Furthermore there will be a battery ...
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1answer
44 views

What is the best practice to measure 3 phase grid voltage using a dsp chip for synchronization?

I want to measure the current grid voltage to synchronize a dc power supply with the grid using an inverter. Now I'm particularly interested in finding noise and harmonic information about the grid ...
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0answers
31 views

Odd red noise appears on the display of my Samsung SyncMaster 943N monitor [closed]

I have a problem with my Samsung SyncMaster 943N monitor. For some reason red noise appears on the displayed screen. Notice the red noise around the white zones in the image: Tried connecting it ...
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31 views

Waterfall diagram for car starting coil signal/interference

Does anyone have a waterfall diagram for the signal given off by an ignition coil when a car starts (or is operating)?
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20 views

single ended signal(low voltage and current) across cable, noise attenuation

I am running an analog signal 0-5v across 20ft of shielded cable. The results are less than stellar but with some software signal filtering, the results are ok. However, I still want to reduce the ...
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1answer
68 views

How to Reduce Serial Noise from a Refrigerator

I am controlling the compressor of a compact refrigerator using an Arduino Mega and an opto-isolated relay block. The Arduino is connected to the PC using a serial over USB (Atmel version). Since the ...
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2answers
291 views

Why does a metal sheet block all noise, but not when wrapped around a cable?

If I place a flat sheet of aluminum foil between a near-field probe and a noisy wire, the sheet completely blocks the noise. However, if that sheet is then wrapped around the wire, it seems to have no ...
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1answer
37 views

Data acquisition noise or defect?

I'm using the following setup to measure a voltage across a resistor. I measure it both by a DAQ system and an oscilloscope. Below is the illustration for the setup: DAQ is the data acquisition ...
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21 views

Sensor analog output changes while using Xbee

We are using a adafruit noise sensor for activity detection. We have setup it with Arduino Promini. It works well. But when we attached Xbee Pro S2B with our setup, the analog reading of noise sensor ...
2
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1answer
79 views

Floating plane in PCB

I just designed a simple class D amp pcb in which the ground plane is in a star configuration with the IC as center as suggested by the datasheet (cuts in signal areas vs big cap areas, etc..). VCC ...
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1answer
107 views

Is a 1.8v supply too low for driving a long bus?

I'm designing a circuit comprised of two boards separated 23 inches away and connected through a ribbon cable which carries an I2C bus (400Khz) and various interrupt digital signals, plus VCC and GND. ...
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2answers
50 views

What's the most effective way to prevent EM noise from coupling onto a cable and radiating out?

I've a PCB radiating noise inside a metal enclosure (this is Product 1 from this question here). Unfortunately, I can't change the PCB itself, so I'm having to tackle the problem by other means. I ...
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1answer
120 views

measuring microampere current without noise

I have a constant current source that can output current in the range of 0mA to 1mA. I am driving 100 microamps through a load resistance (1.5Kohm) and then connected another test resistor (1.0 Kohm) ...
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0answers
64 views

Multipoint Ethernet cable as an RS485 data bus

How can I create multipoint connections with an Ethernet cable an retain the high reliability / low noise achieved by the wires being twisted in couples? I think I need to create Faraday cage, but I ...
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1answer
30 views

Analog input dependent on samples quantity used in averaging

I found this issue using arduino but IMO this relates more to electronic eng. I use pin0 without any pull-up/pull-down/connection. Simplified code: ...
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1answer
63 views

Should you always band limit a signal into an opamp when you are trying to control noise - even at DC?

Saw a Youtube video from TI talk about opamp noise and one of the points they made was limit your bandwidth. TI:How to select an op amp based on datasheet noise specs While I do understand the ...
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1answer
100 views

Audio amplifier coupling issue

I keep getting oscillation / uncontrollable noise with the following circuit. My input is a balanced audio signal which goes through a TL082 op amp configured as a differential amp. The output of ...
2
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1answer
114 views

Filter noise from a high voltage DC-DC converter

After finding a couple of triodes lying around I decided to build a valve preamp. I've built a simple boost converter based on a 555 timer to generate anode voltage. The circuit is powered from a ...
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1answer
44 views

I'm getting a noisey/square wave output for my mux/demux?

I am using a "CD74HC4051 High-speed cmos logic analog multiplexer/demultiplexer" I put 5V to VCC, put my oscilloscope probe to the common out/in, put 3.3V to A1 (channel in/out), and have a wire ...
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2answers
302 views

Accelerometer double integration error

I wanted to use an accelerometer or IMU to measure speed and displacement over a period of about 1 minute or 400m. From this answer I found at stackoverflow, the error propagates at a rate of \$t^2\$ ...
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2answers
36 views

Stepping-down DC voltage (at low current) in the presence of an audio circuit

I'm trying to add a bluetooth audio receiver to an old 12V battery-powered boombox. The receiver board takes 5V and shouldn't draw much current, but I'm trying to understand which type of DC-DC ...