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

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9 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
50 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
104 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
41 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
72 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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46 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
56 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
59 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
58 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
40 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
208 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
27 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 ...
11
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2answers
171 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
37 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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0answers
36 views

How to make a noise radiator to check the resistance of systems against radiative noise?

You have seen many good AVR projects that were made to be used in industrial places and who had made it was sure of the noise resistance but the device didn't work. It was better if there were a way ...
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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
43 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
84 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
22 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 ...
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0answers
36 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
45 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
482 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
24 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
39 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
62 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
53 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 ...
3
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4answers
148 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
53 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
64 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
86 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
213 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 ...
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2answers
395 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
380 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
46 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
47 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
195 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
62 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 ...
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3answers
63 views

How to convert noise to noise density in mic pre amps

I am trying to compare two low noise mic pres for the lowest noise, and I am looking at the TI1012 and MAX9814 MAX9814: ♦ Low Input-Referred Noise Density of 30nV/√Hz TI1012: Output Voltage Noise ...
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1answer
74 views

Filtering Noise on Strain Gauge Circuit

I am making a digital weighing scale circuit and currently having difficulties understanding filters that are commonly used to reduce noise in these type of circuits. My load cell is a full-bridge ...
2
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3answers
198 views

How differential amplifiers help reduce noise?

First off, I'm new to electronics. Can anyone please explain how differential input reduces noise? My understanding (please correct me if I'm wrong): noise usually gets added to the original signal ...
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2answers
76 views

Noise on power line when charging USB

For the starter: I have build device that use DTMF code to control LED light the device can be both power from USB charger or integrated on the board PoE module. The power is also used to power ...
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2answers
78 views

How does water damages the phone lines?

Today, we just replaced the phone line which was damaged due to moisture and were causing a great deal of disturbance and noise in the phone. What exactly causes this noise? Does the signals gets ...
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0answers
66 views

Design a low-pass RC circuit to eliminate SMPS noise

As per a previous question I've asked - trying to track noise from a circuit. I've built a audio relay switch and the audio path seems to be inducting noise from the relay power supply (shared ...
0
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1answer
96 views

Clean DC power supply from a dirty souce

I'm building a guitar pedal which uses a series of relays to switch various signals. The relays are currently being powered by a cheap 5V switchmode supply and the audio path is inducting high ...
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2answers
80 views

OpAmp: Better to actively attenuate, or drive full range into a divider?

I want to get a +-15V differential signal (60Vp-p) into an ADC that has a single 3.3V supply. When I asked a friend to proofread it, he was concerned about the noise performance of R5-R6 vs. using ...
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2answers
202 views

Arduino - How do I reduce the noise in my circuit

I have a fairly simple circuit consisting of an arduino an accelerometer and an amplifier. I am collecting data from the accelerometer using I2C and playing some sounds through a switching amplifier ...
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0answers
54 views

Long range PIR sensor circuit

I would like to develop a long range motion sensing circuit. I have done some research and the most cost-effective solution seems this. This approach is based on the use of more PIR sensors. However ...
3
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4answers
159 views

How to select gain for an amplifier before ADC?

The circuit has been simplified as shown in the picture. Signal source is connected with an analog amplifier, which amplifies the ac signal and also raise it by 1.5V to match with the range of the ...