Questions tagged [interference]
For questions about electromagnetic interference (EMI); see also the [emc] tag.
350
questions
1
vote
0
answers
50
views
Second shift register 74HC595 with wrong outputs
I have a controlling panel at my wall to control which electrical device is active (because I have only a single 10 A phase and running way to often to the breaker).
The principle is easy: read Input ...
0
votes
1
answer
36
views
Would grounded conductors placed on skin prevent signals from reaching a shielded body part?
Here is the scenario:
You are in an environment where there are sources of EM signals that your body will pick up as though it were an antenna via capacitive coupling, i.e. what happens with the 50/...
2
votes
1
answer
58
views
Understanding opamp circuit, 13 MHz (interference?) amplification
I have the circuit drawn below soldered to a prototyping board.
Final goal will be to test body coupled communication in which this device must be the receiver.
First, I added a high-pass filter a ...
- 250
0
votes
1
answer
76
views
Why does EMI from a DC motor lock up my Arduino, while consumer electronics remain unaffected? [closed]
For example: my laptop, while connected to the Arduino over USB, runs just fine, while the Arduino locks up.
- 1
1
vote
1
answer
72
views
Two laser diodes beat frequency
With a single laser diode, the interference pattern of the light with itself gives a beat frequency of zero.
Given two laser diodes (same wavelength, same manufacturer), the interference pattern of ...
1
vote
1
answer
58
views
Two transformers with common ground (Split supply)
When and where you can have a common ground? In this case between 2 different transformers. The initial goal is to have:
One Ground
-15 V
+15 V
+12 V
The split 15 volt supply will be used for ...
- 11
0
votes
0
answers
74
views
How does an integrating receiver work?
I am reading some papers and in one paper, the working of an integrating receiver is mentioned to remove (periodic) interference from the received signal. The paper explains the working as such:
The ...
- 250
0
votes
0
answers
64
views
Intersymbol interference on PAM Trasmitter
I would like to simulate on Matlab a PAM signal which, travelling on a time-dispersive communication channel, contains intersymbol interference (ISI).
I have 'built' the transmitter by generating:
8-...
- 35
11
votes
3
answers
1k
views
Why does a 50 Hz, 200 mV sine wave appear sometimes on my portable oscilloscope without a probe connected to anything?
I have a portable oscilloscope, and when I connect just one probe to it, sometimes, moving the probe into the air without connecting it to anything, then I can see (in some of the places of my house) ...
- 239
2
votes
1
answer
78
views
Special considerations for circuit prototyping near an airport?
I am a hobbyist circuit designer. I recently moved to a home near an airport. I am directly under the flight path, and sometimes planes fly as low as 500-1,000 ft over my house. My circuits are ...
- 521
0
votes
0
answers
62
views
RF interference on GPIO?
Novice here.
I think I have an RF interference problem with a 3.3v digital device used to control lights via an API over wifi and need some help making sense of it.
I have an esp8266 based device with ...
- 101
0
votes
0
answers
30
views
RF noob here, help with antenna extension & noise reduction keywords
I have a design restriction. I have 24-bit adcs on the same circuit as a 4g lte module and "i have been told" that the ~250mw (~24db) of the 4g module interferes with adc measurement , i was ...
0
votes
0
answers
31
views
What happens when the attenuation between radios in an RF test bed becomes higher than the RF leakage attenuation of the coax cables?
If I have an RF testbed with radios connected to each other via an attenuation matrix, what happens when that attenuation between radios exceeds the rated attenuation of the braided shield coax cable (...
- 83
0
votes
1
answer
53
views
Shielded header cables or alternatives for IDC / 2x8 header cables
For my project I currently use 2x8 IDC cables, all of them carrying digital data, like SPI, I2C and TDM (digital audio). As I have tested, I found that these cables bring in loads of noise to the ...
- 209
0
votes
3
answers
130
views
Could multiple transmitters on the same frequency work if phase-locked to GPS? (gedanken)
I've been noodling this concept for a while; it seems to me that if it were actually workable somebody would be doing it already, but I haven't heard of it happening. So where do I go off the rails ...
- 1,248
0
votes
1
answer
90
views
Can ferrite beads deal with electromagnetic interference on attached PC peripherals?
This questions is more related to computer + external electromagnetic interference with my PC.
I'm using a PC where one USB 3.2 Gen2 port is occupied with a USB 3.0 USB hub. I'm facing problem with ...
- 239
0
votes
0
answers
35
views
RF noise filtering chassis or power return?
I need to place some filtering on the IO lines of a DC powered device.
The RF noise is induced or conducted into the chassis of the equipment and also into the interconnecting cables. The frequencies ...
- 161
1
vote
1
answer
163
views
FM radio interference on PCB
I have designed a few PCBs for one of my projects. The PCB is picking up FM radio signals. I can see this as spikes in the spectrum where each radio station is broadcasting.
I tried covering the PCB ...
- 25
0
votes
2
answers
84
views
Coaxial 75ohm cable parallel to electrical mains 127V AC @ 60Hz
Everywhere we look at, the same recommendation is made: "never run coaxial cable parallel to electrical cables". Well, I get it, but.... I have no other option™. More than that, those cables ...
- 121
1
vote
1
answer
110
views
2-stroke engine interferes with Arduino project
I'm currently working on a bicycle project where I have mounted a 25cc 2-stroke (weedeater) engine at the rear of a bicycle. I have also created a speedometer (based on Arduino) which is mounted on ...
2
votes
1
answer
242
views
PCB Ethernet instability - CM4 Breakout Board
I am creating a breakout board for the Raspberry Pi CM4 which should support Gigabit Ethernet and POE. I embedded a magjack onto the breakout board.
I am struggling with the connection stability, ...
- 143
0
votes
0
answers
80
views
Help with the design of a RF PCB transmitter
Edited with previous suggestions
I work for a company that builds (redacted for privacy), and a big company lent us a special GPS anti-jamming device, and I am in charge of implementing and testing ...
1
vote
1
answer
116
views
Puzzling mains-frequency interference at output of signal generator
The output from the 1940's-era modulated oscillator I'm restoring is being fouled by a 50Hz signal and I haven't been able to find the cause of it - so I'm far from being able to eliminate it. It's a ...
- 629
8
votes
2
answers
949
views
Radio static due to neighbor's shredder
I live in a condominium apartment building. I have a Bose Wave Radio with a dipole antenna connected. I frequently listen to FM radio stations. One of the stations I listen to has pretty good power ...
- 689
0
votes
0
answers
36
views
Avoid body interference in a parallel plate capacitor
I'm making a parallel plate capacitor. Each plane is 4"x6" and they are separated at about 1cm.
I am using an LC meter to measure the capacitance, and the results agree with the parallel ...
- 80
0
votes
1
answer
215
views
Coax cable 130 dB vs 135 dB, which one is better?
I need to buy some coax cable for TV via satellite. I see they are marked in dB: 135, 130, 120 down to 95. Then there are multiple layers (up to 5) and shielding copper (cu) vs aluminum (alu.)
Is my ...
- 343
0
votes
2
answers
65
views
LCD scrambled by interference from RF plasma
My lab uses a custom-built setup to generate reactive plasma; basically metal plates in a vacuum desiccator energized by a BD-10A. I've built an arduino-based control box for it to allow more precise ...
- 101
3
votes
1
answer
277
views
Two devices sharing the same coaxial cable, what frequency channel should I chose? [closed]
The 2-stories house is equipped with a coaxial cable that has wall plugs in 1st and 2nd floors (it's also connected to the antenna on the roof).
Our IAP installed a modem for Internet (Arris CM820C) ...
- 281
0
votes
0
answers
69
views
Can inductors interfere with a BLDC motor?
I'm working on a student project. It involves running a brushless DC motor with 70uH external unshielded inductors on each phase.
Can the inductors, seeing as they generate a magnetic field, somehow ...
1
vote
3
answers
169
views
Interference effects on a wireless signal
I am trying to get my head around the effects of interference on a wireless signal and its signal strength. I do not have an engineering background, but I do have a background in wireless sensor ...
- 13
0
votes
1
answer
102
views
Can I mix three wires that carry single phase 240V AC and four wires that carry USB signals into a signal custom cable?
I am planning to design a system that requires AC power supply as well as a USB connection. I found a connector that has provision for the same here.
If I were to pass 240 VAC single phase along with ...
- 73
3
votes
1
answer
66
views
Roughly how fast can a constant current LED circuit ramp to 1A without EMI issues?
I have a constant current circuit supplying a 1A LED for a carefully controlled strobing application; for my application the LED needs to turn ON (no dimming) for ~1ms and then OFF (fully off), at a ...
- 69
0
votes
1
answer
113
views
Is the amplitude of the sum of 2 transmitters of white noise at a given frequency greater than each individual transmission?
If you have two antennas \$T_1\$ and \$T_2\$ each broadcasting 10GHz Gaussian White Noise at the same receiver, each with an EIRP of say 20 dBW with a random phase offset between them, then is there ...
- 101
0
votes
1
answer
171
views
Running and grounding paired shielded cable thru a connector
I need to run two logic signals around a vehicle, so for good measure, regardless if its overkill or not, I want to use a shielded single pair wire for that job. At one point it should be crimped to ...
- 43
0
votes
1
answer
178
views
NFC and magnet interference in a concrete piece
Do you know if both NFC and a magnet would work correctly in this scenario?
I´m designing small pieces of concrete (imagine chess pieces) with three layers: magnet inside, NFC tag in the middle, and ...
- 11
0
votes
2
answers
128
views
Flashing random LEDs when multiple wires fished through hole
I've been building a large, 3D printed dodecahedron infinity mirror. Prior to adding the polycarbonate pentagons with mirror film applied, the LEDs worked perfectly in the frame. Once I fished the ...
- 185
-1
votes
2
answers
170
views
What can negatively impact a motherboard's / CPU's clock generator / oscillator?
Is it possible for a clock generator / oscillator to be skewed by something from the electrical grid (e.g. to work perfectly fine at place A, and have issues at place B - all reproducible)?
What would ...
0
votes
1
answer
215
views
Bluetooth antenna on top of large metal object and other RF questions
I've been doing some research on RF antenna design considerations but haven't really found anything close to the situation my device will be in. I am designing a wireless sensor for my FSAE team that ...
- 69
1
vote
2
answers
52
views
RF interference in high node density 2.4 GHz networks
These days, there are a lot of products that are working on 2.4 GHz RF - mobiles, laptops etc using 2.4 GHz wifi, earphones using BT, home automation products using 2.4 GHz zigbee. Though these ...
- 7,696
0
votes
2
answers
86
views
How best to allocate signal wires to 4 twisted pairs that best reduces inteference
I have to transmit digital signals 30meters including power. I am going to use a cat 6 ethernet cable with 4 twisted pairs (8 wires in total). I can already assure that my signal gets to the other end ...
- 669
0
votes
3
answers
145
views
Relay is switching by touching optocoupler with finger
To switch a 12V relay with a micro controller, I designed ("borrowed") this schematic.
Build the pcb and it works great. But there's a little bug that got me a bit worried. If I touch the ...
- 1
0
votes
1
answer
74
views
Desktop screen goes black because of radiowaves from phone?
I hope this is the right community for this phenomenon.
For some weeks my desktop screen went black for some seconds - no warning prompt no nothing - and then came back to life.
I usually change my ...
0
votes
0
answers
510
views
How to stop LED EMI on capacitive touch sensor TTP223
I am trying to make a piece of wood touch sensitive. I have a piece of wood carved with runic letters.
I inserted LED's inside then filled the letters with epoxy resin.
When I touch one I want the ...
- 317
0
votes
0
answers
58
views
RF line: routing it orthogonal over SPI digital signal lines
SPI will be kept below 1MHz. RF signal is under 434 MHz. Is this crossing fine through the big zero ohm resistor ?
Side question: will the outermost SPI line (it is the chip select one), or any of the ...
- 1,000
8
votes
4
answers
920
views
Why does analysis indicate that ground lifts do not fix ground loops?
Note: "Ground loop" in this question refers to a ground loop caused by linked magnetic fields. (Sometimes ground loop refers to slightly different scenarios.)
Recently I've been looking into ...
- 453
3
votes
1
answer
123
views
Oxygen sensor voltage changes when machine is powered on. Interference?
I built an Arduino Uno based control panel for an altitude training machine, which connects to an oxygen sensor. The value is amplified by an instrumentation amp (INA122P) and read into the analog ...
0
votes
3
answers
78
views
Better to Opto-Isolate on Sending or Receiving End? Isolating to Avoid EMI
I am working on an art project using some modified bug zapper circuitry to produce loud and bright sparks. I have the circuit working and the sparks are very impressive, but I'm running into a issue ...
- 331
2
votes
1
answer
96
views
Protecting against static interference/noise for encoder
I have a chassis that is made from box steel beams, they are painted/surfaced. Attached to it is a fiberglass tub which can rotate. Attached to the fibreglass tub are supports and mounts where some ...
- 31
2
votes
2
answers
623
views
Best configuration for ethernet-as-speaker-wire?
I'm hooking up a couple of small speakers (3w max each) outside, and I have a small run in my house from inside to out that was done with ethernet cable. There's no way I can pull speaker wire through,...
- 23
1
vote
1
answer
539
views
Power Supply issues with CAN bus
I am currently working on a system using C# for a windows GUI with an Ixxat USB-to-CAN and an STM32F303K8 that runs CANopen, The system itself is running fine I can send and receive messages to and ...
