As of May 31, 2023, we have updated our Code of Conduct.

Questions tagged [interference]

For questions about electromagnetic interference (EMI); see also the [emc] tag.

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74 views

RF interference from laptop power [closed]

I've been using a pair of RF receiver/transmitter units for making my PA speakers wireless but I have an issue with static noise coming through when connecting my laptop power on the same power ...
1 vote
3 answers
425 views

I2C noise from 433MHz transmitter

I have built a little thermostat based on BMP280 temperature sensor over I2C, ESP8266 Lolin v3 and STX882 433Mhz transmitter. I have not added additional pull-up resistors or decoupling capacitors. ...
0 votes
1 answer
29 views

Interference of RF currents with a combiner

I am trying to understand what happens to 2 RF currents flowing in separate planar waveguides (such as microstrip lines), when combined with a power combiner. More specifically, will they interfere, ...
0 votes
1 answer
256 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 ...
2 votes
1 answer
249 views

Weird SWD debug port behaviour

Today I have started to encounter strange problems with SWD debugging. The debug only works if I keep my finger on the SWD pins. To be more interesting I have the same problem with the boards I was ...
0 votes
4 answers
87 views

Weird component in radio player interferes with FM functionality of the radio itself

I got my hands on an old radio player which has both cassette player and FM/AM functionality. I got constant noises while playing on FM and it turns out to be some weird component on the cassette ...
2 votes
1 answer
57 views

Picking a pi- or T-filter to suppress radiated interference on supply line

Normally when I design suppression filters I use π-filters for data lines and T-filters for supply lines as supplies generally have a lower output impedance than data pins. I now have the situation ...
4 votes
2 answers
311 views

USB shielding, device or host side?

I have an SBC with a USB host port, but it is exposed as male header pins rather than a female USB port. I have soldered female headers to a USB cable and have a working but intermittant connection, ...
1 vote
0 answers
54 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
59 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 ...
0 votes
1 answer
37 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
61 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 ...
0 votes
1 answer
89 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 vote
1 answer
108 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
65 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 ...
1 vote
4 answers
4k views

How to avoid clash of multiple RF modules [315/433 Mhz]?

I am working on a project which requires multiple RF working together (around 100). This will be one way communication from TX -> RX. I will be setting up multiple cheap 433/315 Mhz in one particular ...
0 votes
0 answers
67 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-...
0 votes
0 answers
84 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 ...
41 votes
2 answers
38k views

Does Bluetooth interfere with WiFi?

I've read that WiFi b/g/n is using 2.3995 to 2.4845 GHz. Bluetooth is in between: 2.4000 to 2.4835 GHz. So what will happen when I put a Bluetooth sending device next to a WiFi sending device? Will ...
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) ...
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 ...
18 votes
1 answer
406 views

Unusual interference

I'm experiencing an effect somewhat like GSM frame-rate audio break-through in my audio systems - completely different frequencies but equally wideband. I've noticed it occasionally in the past - ...
3 votes
2 answers
514 views

I2C gets Interference from motors in an Arduino project

I built a small Arduino "robot" on a tracked chassis. The device uses MPU-5060 for direction finding (on a prototype shield) and Adafruit MotorShield v2 to control two 320-type motors. The ...
1 vote
0 answers
99 views

IR receiver somewhow being triggered by cell phone screen?

First time asking a question here. I am curious why the TSOP4838 ir sensor is acting erratically when my Google Pixel 2's screen is facing it. As you can see from the schematic, I have a 555 arranged ...
0 votes
0 answers
75 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 ...
0 votes
0 answers
31 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 (...
0 votes
3 answers
157 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 vote
1 answer
274 views

Low frequency antenna (128, 80 kHz) interference

Using the antenna, the antenna is used to identify the individual parts of the animal individually. As livestock passes by, the antenna recognizes the individual animal tag. The antenna frequency uses ...
0 votes
1 answer
69 views

Mesh Wire opening size for EMI filter at frequency of 30 MHz

I want to use a mesh wire and I wanted to know how do I calculate an opening size of a mesh wire that can filter 30 MHz frequency.
1 vote
1 answer
698 views

Common-mode chokes in series

Is it common practice to combine common mode chokes back-to-back in series to eliminate/reduce RF interference in different frequency bands? As a random example, placing this in series with this in ...
0 votes
1 answer
119 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 ...
0 votes
0 answers
37 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 ...
1 vote
1 answer
172 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 ...
0 votes
2 answers
87 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 ...
1 vote
1 answer
594 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 ...
2 votes
1 answer
2k views

Possible reasons for DC fan failure

In my design I have a constant problem with failing 24VDC fans. The fans are used all across the machine, however they fail in only one position, so I excluded faulty fan model as a source of problem. ...
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 ...
2 votes
1 answer
277 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, ...
1 vote
1 answer
119 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 ...
0 votes
0 answers
83 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 ...
8 votes
2 answers
968 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 ...
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 ...
0 votes
1 answer
269 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 ...
0 votes
2 answers
70 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 ...
3 votes
1 answer
324 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) ...
0 votes
0 answers
71 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
211 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 ...
0 votes
1 answer
107 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 ...
3 votes
1 answer
67 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 ...

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