About issues caused by electrical noise, or improving the Signal/Noise ratio of an analog circuit.
10
votes
2answers
1k views
How do you choose an inductor for connecting separate ground planes?
On a board with separate analog and digital ground planes connected at one place, the connection is often made with an inductor. How is this inductor chosen? Obviously it has to be able to handle ...
9
votes
3answers
597 views
Why use LNAs in a noise generator?
In this Maxim appnote the avalanche noise of a zener diode is amplified by two cascaded LNAs (Low-Noise Amplifiers):
You can guess what my question is: why use low-noise amplifiers if you want ...
3
votes
2answers
515 views
Power supply noise in audio
I have what is surely a classic problem with regard to power supply switching noise and audio but I am unable to sort myth from reality with regard to what I found so far on the topic.
Setup:
I ...
3
votes
1answer
593 views
What component of my phone charger produces chirps and how does it do that?
My Nokia cell phone is charged with a very lightweight compact charger similar to this AC-15 (can't find the one I actually use).
While the battery is close to empty the charger works silently - just ...
14
votes
6answers
2k views
Noise reduction strategies in electrophysiology
When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio.
These signals are usually in the 10uV ...
13
votes
2answers
1k views
Noise and what does V/√Hz actually mean?
Noise figures in (opamp) datasheets are in expressed in V/√Hz, but
Where does this unit come from, why the square root? and how should I pronounce it?
How should I interpret it?
I know lower is ...
10
votes
6answers
3k views
Why does GSM cause speakers to buzz?
Based on numerous internet resources, speaker wire acts like an antenna which picks up the transmitted signal of nearby cellphones and causes the speakers to buzz. But I'm not really buying that...
A ...
7
votes
4answers
3k views
How do I eliminate PWM noise when driving a fan?
I'm driving a 12V 0.11A brushless DC fan with PWM using an MSP430Gxxxx --> TC427CPA FET driver --> BS170 N-FET. The fan is on the low side of the FET.
Even with a duty cycle of 90% and a frequency of ...
9
votes
3answers
533 views
What problems could occur when chaining 40 shift registers?
I'm planning on chaining together 40 x 74HC595 shift registers. The whole chain of 74HC595s will be controlled by a 5 V microcontroller, which will generate the ...
5
votes
4answers
744 views
Advice on cleaning up 5VDC from a wall-wart
Assumption: I think it's generally true that commercially available AC/DC wall-worts can be expected to be pretty noisy (e.g. you can't count on much better than 5% stability).
Background: I'm ...
7
votes
1answer
193 views
Ground noise and voltage drop problem
I have an RC device powered by a 3.7V poly battery, which includes a motor and a 40KHz sonar. The voltage across the sonar sensor is amplified and then adc-ed. The motor is driven by a 2KHz PWM.
When ...
4
votes
4answers
2k views
Implementing guard trace/ring in PCB design
I have read here and there some articles about pcb guard trace/ring. But none of them discussed how to correctly implent it. What I could find were some pictures and comparison that cant help me at ...
3
votes
3answers
518 views
Novice question about low-pass filter
I am trying to construct a simple low-pass filter for the following scenario: A high-voltage DC signal with lots of noise. I looked at Wikipedia's article on a simple passive low-pass filter. I ...
2
votes
2answers
239 views
Minimization of electrical noise?
I read a textbook and it states that:
"The effects of electrical noise can be minimized using circuitry external to the MCU"
I don't understand how this scenario works. What does it mean with ...
4
votes
2answers
1k views
I2C - Cannot read temperature from TC74 with PIC16F887
The question was:
I want to read temperature from TC74 using I2C module of PIC16F887, however, in Proteus
simulation, I see noises in I2C Debugger Tool's output.
...
4
votes
6answers
871 views
What's causing this high frequency ripple on the output of my LM317?
I'm using an LM317T to regulate 5V to 3.38V for a microcontroller. R1 is 330 ohms and R2 is 560 ohms. There is no input capacitor and the output capacitor is a 470µF 25V, because I had that value in a ...
3
votes
3answers
228 views
What could be causing this sine on 7810 output when powering BLDC fan?
I'm powering a 12 V computer fan with a simple 7810 circuit shown here:
When the fan is connected to the regulator, on the output I get this wave:
When I zoom out in time, I get something that ...
2
votes
0answers
360 views
Voltage Fluctuations in Arduino-opamp-thermistor circuit [closed]
I'm working on a board that takes measurements of voltage off a thermistor through an Arduino and amplified by an opamp (really an instrumentation amp AD623), also there are two potentiometers. See ...
0
votes
2answers
193 views
Noisy data line clears up on wiring up multiple output pins of uC to Logic Analyzer
Some people reading my question might be familiar with a string of questions (latest being this one) where I have been asking about how to decode data from an ISM-band ASK/OOK type RF receiver module. ...
-2
votes
1answer
133 views
How strong are the Arduino boards relating to interference robustness?
In my previous question the problem was related to EM noises with the Arduino boards, then I asked myself: How strong are the Arduino boards relating to interference robustness?
For example, if I ...
