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

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4
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2answers
61 views

How does Hybrid Ground Works?

The text that is above the figure is from my textbook and i am having difficulty to understand what it is trying to say because it's not in detail!! why only remove high frequency and prevent low ...
0
votes
1answer
23 views

Cut-off frequencies for common mode and differential mode filter?

Attached is the circuit section for the differential signal amplification. The circuit is comprising of common mode and differential mode filter capacitors.So there will be two different cut-off ...
2
votes
1answer
57 views

Noise can be Differential or Common!

I have a basic understanding on this topic but i still have some doubts, my text books says Differential means it will have impact on one of the 2 signal nodes. and Common will have a common impact on ...
-4
votes
1answer
46 views

Connecting to oscilloscope ground reduces noise significantly?

I designed an isolated ADC system. The system is noise when left alone. However, if I connect oscilloscope probe's ground to ADC system's ground, the noise improves significantly. Is my board ...
0
votes
1answer
44 views

reducing the effect of a parasitic capacitor!

According to my text book, the second figure says that the noise current returns to their source without flowing through z1, how is that possible? if the noise returns why doesn't signal/ original ...
0
votes
0answers
24 views

High-accuracy non-invasive current sensors for sub-metering [closed]

Let the smallest home-appliance for which we need to measure current be of 10W rating. For a 220V-240V supply, that current is just above 40mA. One of the main intentions here is to perform ...
1
vote
2answers
75 views

Reduce noise in Buck converter:

I'm making a buck converter, this is the circuit I've: The average voltage at the output is ok, but I'm getting lot of noise at all nodes of the circuit: I'm using as a main source a 30V 5A bench ...
0
votes
0answers
108 views

Ringing at the output of a microcontroller

I'm generating a pwm signal of 125khz, I've no problems with the frequency but the signal has an overshoot: This is a big issue because I'm using this signal to control a dc/dc converter and the ...
0
votes
2answers
20 views

Noise source in orcad pspice

I have a certain circuit and I want to see its ac performance when I send in certain noise as a signal. is there some option like noise source similar to sine etc signals in orcad.... I can make my ...
0
votes
1answer
47 views

Less noise when not following LED Driver datasheet

I designed a board which uses a LED driver (datasheet). It clearly states, DO NOT connect DIM- to Vin-: However, these are the waveforms I get on Analog DIM pin when they are disconnected, and ...
1
vote
1answer
84 views

Noise from stun-gun based butane torch ignition spark is locking up ATmega328 microcontroller

I have a stun gun (http://www.amazon.com/VIPERTEK-VTS-989-Heavy-Rechargeable-Flashlight/dp/B00FPE6UN2) which I am using to create a large 1/2" electrical arc through the air to remotely ignite a ...
0
votes
1answer
35 views

Getting rid of electrical noise produced when one touches amplifier and amplifier's dials

I purchased a Lepai LP-2020A+, which is a pretty good little amp for the price, but I've modified it to make it much better and decided it deserved a better casing to look the part, too. So I ...
0
votes
1answer
57 views

Switching power supply noise and grounding

So I have a +-15 V and a neutral switching power supply. As far as I can see the outputs are floating. The power supply has no earth connection. Voltage from negative terminal to neutral and to ...
0
votes
0answers
41 views

Do I need to worry about FCC emissions when using PWM?

I have a AC-connected (though an adapter) unintentionally radiating device that runs a large DC motor (12v, ~6a continuous) under <10khz PWM control. Naturally, switching this large a motor ...
0
votes
0answers
64 views

What LDO has lower noise: AMS1117 or AP2114?

I'm trying to choose a low noise and low cost 500mA to 1A LDO for my VCO project, but i'm having trouble figuring out which of the AMS1117 and AP2114 choices has the lower PSRR noise. Each component ...
1
vote
2answers
58 views

How suppress bounce-related turn-on spikes in DC bench power supply?

I'm taking a refining pass on my DC Bench Power Supply design. It generally works quite well on veroboard, so I thought I'd move on to SMD PCBs and refine the design while working out a few of the ...
1
vote
3answers
109 views

Protection For This Circuit

This is my theoretical (haven't tested yet) circuit I have designed for a project of mine. Electrics is a new field for me so please raise flags if my circuit has flaws. Assuming the circuit is ...
0
votes
2answers
90 views

4-20mA Error vs Distance Relationship [closed]

Is there a relationship between noise error and distance for 4-20mA? This noise error could be expressed as S/N ratio, percent from full range, dynamic range, noise density, resolution, etc. Digital ...
14
votes
7answers
2k views

Is there any downside to using a larger than needed smoothing capacitor?

I work with low-power DC voltage regulators. I am already aware of the formula to calculate the size of smoothing capacitor(s). This can be an iterative process of testing one size with a scope and ...
2
votes
3answers
93 views

Mains hum without ground loop

When I hook a device to the monitor input of my digital piano, I get a very noticable 50Hz hum. I understand that the monitor input doesn't have to be particuarly good quality, but it really is ...
3
votes
3answers
167 views

What is the peak - peak voltage of 15mV rms white noise?

I've been experimenting with zener diode based noise sources. I have such a source for which I want to determine the peak to peak noise voltage. I've measured the noise with my trusty multimeter and ...
0
votes
1answer
23 views

What is the difference in the input from inbuilt microphone and an external microphone amplifier?

I wrote a MATLAB script interfacing my laptop's inbuilt microphone to calculate the dbA levels of noise in my classroom. (un-calibrated, as of now) I want to now use this dbA calculation script on ...
1
vote
0answers
44 views

Inverting op amp gain using high value resistors and using oscilloscope measuremnts

I built an inverting op amp circuit as shown in above figure using varying values for Rf and Rin. When I used Rf=10kohm and Rin=100ohm, my measured gain (using national instrument's virtual ...
4
votes
1answer
66 views

Grounding Scheme for Signal + Power

Background I am working on a project which requires a both digital and analogue signals along with power and biases to be connected between two devices over roughly 1 metre is quite a harsh (magnetic ...
1
vote
0answers
30 views

Noise inducing on circuit

I am interested in adding noise in two circuits, to examine the filters I designed, and the overall performance of the circuit. I currently have in mind two cases, but I believe in both cases the way ...
0
votes
0answers
33 views

Noise appears in image when IC is cold, disappear once getting hotter

We're using ADDI 7004 to convert signal from CCD to image, but one strange thing we observe is that when the board boots from cold, there are a lot of noise on the image, but once the ADC getting ...
1
vote
1answer
30 views

Why is noise input referred?

Many of the textbooks I have read analyze noise signals. We have a circuit and find the output noise RMS voltage. But there is always the "extra" step of finding the input-referred noise. Why do we ...
0
votes
1answer
27 views

Signal Switching Advice/Recommendation needed

I need to design a switching circuits for this: A tester device is used to test a controller(lets call it controller A). This controller have both input/ouput(analog and digital for each) which is ...
7
votes
3answers
84 views

Alkaline battery noise varies with temp

I had an 9V alkaline battery connected to a resistive bridge, that stepped out the voltage to several analog channels. I was testing the analog channels over temperature and when it got below 10C I ...
0
votes
0answers
35 views

Shortwave RF amplifier transistor selection

I want to design a RF amplifier operating at 1.5 MHz. I'm searching for a suitable transistor (with good noise figure). I have two questions on selecting the transistor: Are low noise general ...
0
votes
1answer
34 views

Reading ECU tacho signal with PIC MCU - noise issues

Am trying to read the frequency of a 0-12V square signal generated by a motorbike ECU with a PIC. Range 20Hz-300Hz I'm getting strange intermittent noise on the output of my optoisolator, and wondered ...
0
votes
2answers
48 views

How to calculate appropriate value for noise-removal capacitor?

I'm still figuring out analog electronics with my waveform generator project. It has a 9V power supply that I split into +/-4.5V rails with an op amp virtual ground (the subject of an earlier ...
1
vote
1answer
51 views

Weird noise waveform on signal line

I'm doing some electrode recordings and a large noise waveform keeps appearing on the oscilloscope (see pic attached). Interestingly the recording set-up functions just fine with a clearly ...
-3
votes
1answer
95 views

noise calculation for LM741 [closed]

my circuit is very simple, i want to calculation output when i apply 0 amplitude sine-wave to do circuit from datasheet, ...
1
vote
3answers
208 views

How to decrease distortion/noise of LM386 amplifier at max gain and volume?

From my previous question, I've made LM386 amplifier and it works better than LM1458 amplifier. I've added gain and bass boost in my LM386 amplifier. How to decrease distortion/noise of LM386 ...
0
votes
1answer
59 views

Hum Cancelling Circuit

Consider the following circuit: I was just thinking about how connecting consumer grade unbalanced electronics together has a tendency to generate hum. For example, I have a little mixer that has ...
1
vote
1answer
63 views

Why the need for capacitive loads?

Pioneer, Kenwood, Sony, Onkyo, Denon you name it, they all have a similar circuit like this: Why they use C1 and C3 for? Thanks
2
votes
1answer
212 views

Triac spurious triggering issue

I have a circuit where I am using triacs to switch home appliances like fan, tube light etc. This is the circuit I am using: (TRIAC1, TRIAC2, TRIAC3 come from arduino GPIO pins) First load is a ...
0
votes
1answer
24 views

How to 'simulate' an input device?

I made a diy guitar amplifier with two seperate amplifiers. When potentiometer is raised something strange and annoying begins - various whispers, noises and reacts really strange. HOWEVER this never ...
2
votes
1answer
78 views

Spurious triggering in TRIAC due to EFT

I am working on a project to control AC load using TRIAC In normal operation it working complete fine But when a fan regulator specifically step type capacitor regulator is used in vicinty the ...
3
votes
3answers
717 views

How to clean/remove distortion/noise in my LM1458 Op-Amp?

I've made a LM1458 Op-Amp based on this video. it amplifies the input music but it produces noise and has low volume. How can I remove the noise and how to increase the volume? when i parallel ...
3
votes
2answers
102 views

Trouble with Schimtt trigger settings for varying sinusoidal inputs

To make my problem easier to describe, I drew the above figures (abbreviated as Fig.). The sinusoidal input comes from a rotating device, from a small alternator(a permanent magnet AC generator). ...
0
votes
0answers
37 views

Signal generator showing an atypical noise power spectral density

As an orientation exercise in the new lab I have started working in, I was tasked with characterizing the phase noise spectrum of some of the signal generators present in the lab. Doing so made me use ...
0
votes
1answer
68 views

Automatic Gain Control Circuit Design

I am designing a receive signal path for Ultrasonic Transducer. The circuit needs to measure time of flight of ultrasound wave pulses with frequency of 1MHz(about 16 periods - 16us). Below is the ...
0
votes
3answers
109 views

How to test if my circuit is affected by noise?

I have a PCB I designed for a project and I'm testing it. In general, it has some analog channels and a MCU to handle all the logic and the communications. I used an isolated DC-DC converter since ...
4
votes
1answer
77 views

Phase noise measurement with IQ mixer

I have a question regarding a measurement scheme of phase noise that I'm trying to implement. The idea is that I have two identical signal generators (I actually do) that generate a sinusoidal voltage ...
0
votes
0answers
29 views

What are the contributors of noise to MOSFETS [closed]

What are the contributors of noise to MOSFETS? Aside from thermal noise.
1
vote
1answer
94 views

Noise in a non-inverting op-amp configuration

I came up with this circuit: With this setup \$V_{in}\$ is the thermal noise associated with \$R_1\$. I've been trough some calculation and I obtained this expression for the apport of the thermal ...
5
votes
1answer
114 views

How can I observe rectifier switching noise?

I understand there is such a thing as rectifier switching noise. I would like to observe it on the bench, but I don't understand its causes well enough to design a test setup. Once in hand, I'd like ...
0
votes
1answer
81 views

100Hz noise from a mains transformer

I bought a new speaker and it hums even with volume knob turned to 0. After opening it up, I noticed it was the iron transformer oscillating (and screwing it tighter does reduce the noise). How is ...