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

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7 views

Arduino Board with Microphone [migrated]

I have this microphone (http://www.digikey.com/product-detail/en/CMA-4544PF-W/102-1721-ND/1869981) and an Arduino Uno board. I'm trying to read audio values off of my microphone (to test the noise of ...
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19 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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0answers
37 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
51 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
64 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
30 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
17 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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27 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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19 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
45 views

How to Reduce Serial Noise from Refrigerator

I am controlling the compressor of a compact refrigerator using an ArduinoMEGA and an optoisolated relay block. The Arduino is connected to the PC using a serial over USB (Atmel version). Since the ...
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2answers
275 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
31 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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14 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 ...
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1answer
63 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
47 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
84 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
49 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
59 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
70 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 ...
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1answer
73 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
43 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
238 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
29 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 ...
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2answers
187 views

Why doesn't aliasing of broad band noise 'pile up' in the sample band?

I recently built a simulation to study sampling, the effects of aliasing and the effects of anti-aliasing filters on the sampled signal. For fundamental frequencies above the sample band it's obvious ...
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1answer
39 views

How much shielding does an ungrounded metal box provide?

How much shielding does an ungrounded metal box provide? That is, a circuit is in a metal box but the box is not connected to either circuit ground nor externally earthed
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2answers
44 views

electrical noise problem with adaptor

I don't know why, but everytime i or someone on the room next door switch off lamp, there is a loud pop coming from the speaker. 1) is that behaviour are caused by my amplifier (diy)(the line in ...
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0answers
47 views

Noise with a MPS-200 power supply

I am testing a 24V medical power supply (Mean Well MPS-200-24) for one of ours future products. The power supply is mounted on a metal chassis connected to the ground. The following schematic shows ...
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1answer
116 views

Linked grounds produce “noise” on Arduino's 5V lines

I'm using an Arduino to realize two "simple" tasks. The Arduino shall receive messages by an 433MHz receiver and send them via ESP8266/ESP-01 to a server. The schematic/wiring plan is attached below. ...
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1answer
26 views

LPF a digital step to prevent crosstalk?

I'm driving a small signal relay using a pair of pins of an MCU. The problem I experience is noise coupling to the signal being switched. I have isolated the noise from the signal relay and that is ...
0
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0answers
38 views

ckt flicker removed with hand touching drain

I have a boost circuit to control LED light. The circuit PI is controlled by microcontroller through software. This circuit works fine till some current at load but as I increase current after some ...
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0answers
48 views

Ripple in simple common emitter DC amplifier output

simulate this circuit – Schematic created using CircuitLab Hi. I am experimenting with this circuit to drive a piezo stack actuator. The piezo actuator will be connected across the ...
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2answers
584 views

Reduce noise from a Hall effect sensor

I am currently working on a magnetic levitation project using a Hall effect sensor for distance measurement. I drive the coil using two 12 V car batteries in series to form a 24 V DC source, ...
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1answer
32 views

ADXL 345 Noise Issue for my use case

I am building a solution where I want my MCU to wake up based on a trigger generated by accelerometer after detecting an activity. There are a number of samples available for this and I am able to ...
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2answers
40 views

Decreasing ADC Reference vs. Amplifying signal

I have a sensor interfaced to ADC but the Range I am getting is not enough, so now there are 2 options, Gain up the signal or Reduce ADC Gain. But as I heard it, reducing ADC gain will cause more ...
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2answers
110 views

Reduction of DC motor noise

I am designing a circuit with a DC motor (http://www.jaycar.com.au/products_uploaded/YG2732.pdf) and some other stuff including a MCU and a LASER, all driven from a single 12V source and am concerned ...
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1answer
58 views

What's the best phone cable for DSL? [closed]

I want to know what cable I should be using to connect my demarc to my DSL modem. When I plug in my DSL modem in the utility room (which is about 20' of wire from the demarc) I get a pathetic 4Mbps ...
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4answers
158 views

Unknown source of noise when measuring with oscilloscope

The original question was how to decrease power supply noise, but after discussion it seems to be just a measurement problem. Case 1: When I short the ground lead to the probe, I read about +-2mV rms ...
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1answer
76 views

RFI on the amplifier due to Wifi

I have a board with a sensitive analog amplifier. This amplifier is optical in nature and it has a gain of 6M times. On the same board there is a Wifi module. Somehow when Wifi is transmitting I see ...
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2answers
72 views

Relay causes USB sound card to freeze

I am using a relay to control a 230 VDC duct fan. Sometimes when the relay turns off my USB sound card freezes, to get it back I have to toggle the power (pull the USB cable, as it is USB bus ...
11
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1answer
1k views

What's with all this noise?

People often talk about noise in circuits. Cheap op-amps are noisy, running a motor can create noise on the supply, and a lot of analog circuits deal with the signal-to-noise ratio (ie: trying to keep ...
0
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1answer
113 views

high speed optocoupler circuit

I have 4n35 optocouplers, I am using these to isolate a motor driver circuit and the Arduino controlling it. I put one on the slave select pin and one on the tx line to the motor controller (there is ...
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2answers
237 views

Electrical noise on guitar pickups from computer. Due to radio interference, or inductive coupling?

When I point my guitar pickups towards my desktop computer from several feet (2 1/2 - 3) away, I can hear a lot of buzzing/clicking, depending on what the computer is doing (idling vs, say, playing ...
3
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2answers
492 views

Physically, how does connecting a PCB to chassis ground reduce noise?

I realize this may seem to duplicate Should chassis ground be attached to digital ground? but the answers in that thread don't explain why one should connect the chassis to PCB ground, aside from ...
4
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4answers
400 views

How to fix EMC problems for existing designs?

I'm going to be looking at a few products that have failed EMC radiated emissions testing and will need to apply fixes in order to make them pass (unfortunately, in these cases, two of the designs ...
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0answers
54 views

How do I draw M-PAM curves of Channel Capacity Vs SNR?

I've seen the following figure in several different articles: (this one was taken from here) I understand that channel capacity of the Gaussian signal is ...
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0answers
53 views

Modified Sine Wave Inverter to power MPPT circuit/microcontroller and Laptop?

I am going into uncharted territory for my senior design project. I need to build an MPPT circuit to efficiently charge a 55AH or 75AH battery. The design because of my lack of programming expertise ...
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2answers
292 views

Ground Loop? Noise from 12v to 5v converter manifest in bluetooth audio source

I've created a custom, bluetooth audio harness for my Jeep WJ using off the shelf parts. Amp - Clarion XC1410 Converter - 12v to 5v buck converter Bluetooth Audio - Logitech Wireless Speaker Adapter ...
3
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1answer
70 views

Power supply noise measurements

Im working on a project where I need characterise the noise from a power supply so I can then design some filters. The power supply provides 5V, 12V and -12V to a set of analogue sensors (hence the ...