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Questions tagged [interference]

Normally related to EMI (see [tag:emc])

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2answers
69 views

MAX 485 performance

I wanted to test the performance of MAX485 drivers. I set up one driver and one receiver 2-3 meters apart. A 100 Hz square wave was being sent down the line. Roughly in the middle of the cable I put a ...
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3answers
51 views

If a PEC surface completely reflects an EM wave, why doesn't an ungrounded shield work?

I was thinking about shielding and its effectiveness. An ungrounded shield doesn't work well for either inductive or capacitive coupling. However, if you think about plane wave theory, a PEC surface ...
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1answer
97 views

Can wax really improve the performance of a FM transmitter?

Why would the use of wax improve the performance of a FM transmitter? Consider this from the video How to build a FM radio transmitter, at 4 min 14 secs: "Theoretically this helps decrease onboard ...
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0answers
52 views

Individual Three Phase Potential Transformers vs Three Potential Transformers in one case

If I had to select between Individual Three Phase Potential Transformers vs Three Potential Transformers in one case for a 600V system (which doesn't require many inches of spacing between phases to ...
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1answer
33 views

Interference from well pump pressure switch and microcontroller

I am using the Parallax Propeller to start and stop timers for an auto racing timing system. Out of 250 cars there were timing issues with about 10 or so. It was very random and hard to diagnose. I ...
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2answers
61 views

Is this quote about interference from wireless charging coils accurate?

This blog post suggests that apple dropped their promised AirPower wireless charging mat because it didn't pass EMI standards, specifically due to the (unconfirmed) idea that they were using a large ...
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0answers
21 views

Using a switching DC-DC converter in high dynamic range current/voltage sensing

I'm thinking of making a power meter circuit which will have a high-side current-sensing amp (LTC6102), a resistive voltage divider for sensing the voltage, a dual op-amp (OPA2365) as a buffer for the ...
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0answers
51 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 ...
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4answers
67 views

How is electromagnetic interference possible when measuring voltage difference?

This question is primarily concerned with audio but it's probably applicable to other areas as well. As far as I understand, EMI is caused by electromagnetic waves adding power to wires as they ...
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1answer
63 views

Wireless phone chargers in a lab environment? [closed]

We are talking about devices that are designed to pump out quite a bit of power in the MHz. Admittedly the chips have comms protocols so they don't spew all the time, and the resonant circuits are ...
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0answers
32 views

Interference on car bluetooth system

I just did some work on my car audio system and am having some problems with interference. I added a bluetooth receiver and wired it directly to my stereo cd player input. The receiver is powered from ...
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2answers
52 views

Shield grounding location for an STP cable in a balanced system

If a balanced source or driver is coupled to a differential balanced receiver via a balanced STP cable as shown in the hand drawn illustration below: in such case I have read that grounding the ...
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0answers
54 views

Grounding the components of a DIY cnc machine

I'm in the process of building a DIY cnc machine. It already runs, but I noticed it has some interference problems (steppers act weird on occasions, the full graphic smart controller LCD has trouble ...
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1answer
54 views

Heaphone amplifier PSU noise

I built myself a headphone amplifier using the LM49600 and a PGA2310 for volume control. This part of the circuit is fairly standard and I don't think it's the problem. I wanted it to be powered by a ...
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1answer
39 views

Standards for conducted EMI testing

I have some doubts to interpret the CISPR standards, one of them is in relation to the test environment for EMI conducted (150kHz up to 30MHz). The minimum size indicated for the vertical or ...
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0answers
73 views

How to reduce spike in Power Supply and GND (SCR + Ignition Coil)

My circuit: Signal coupled in power supply (3.3V) of STM32F103 during spark: Is there any benefit to using this diode (circled in red) or not (without this diode the snubber circuit will start ...
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0answers
14 views

Signal to Interference Ratio in OFDM

I have the following two users that are using two subcarriers in an OFDM system. One user (User 2) is received with a frequency offset due to synchronization problems. The figure below shows the ...
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1answer
70 views

How to conclude the necessity for unbalanced to balanced signal conversion for this scenario?

This is a bit specific system related question about simultaneous data-acquisition for several transducers. Therefore hope you don’t mind for the long intro and the question. It would be too implicit ...
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1answer
438 views

What could be causing this interference and how to eliminate it?

(update: Please also see the major edit at the end) A sensitive electronic equipment Device 1 below is basically composed of a power line EMI filter at the mains entry, an SMPS power supply which ...
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1answer
56 views

Question related to the interference seen at the spectrum analyzer's receiver

I am preparing for the RF course exam. I have an old question on hand that I am trying to solve. Please review my attempt. Question: A simple spectrum analyzer with superheterodyne receiver ...
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0answers
61 views

Electro magnetic interference with Arduino Uno and a portable radio

I'm surprised when I'm working with Arduino Uno, by just sitting beside a portable radio, like when I was powered on both Arduino & Radio and when they are close to each other I got some noise ...
1
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1answer
105 views

How to connect a switch to a microcontroller in an extremly noisy environment

I'm currently working on redesigning the control circuit of a CNC machine (more specific: an Isel milling cutter). Only the digital part will be of interest, I'll keep the old power electronics (motor ...
0
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1answer
53 views

Why are inductively coupled RFID systems put in certain frequency bands when there are no EM waves used?

LF - 125 kHz HF - 13.56 MHz Those frequencies refer to the magnetic field that is used to induce a voltage in the transponder. Can the magnetic fields actually interfere with EM waves in the ...
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2answers
1k views

Long wires causing Raspberry Pi to die?

I've been working on a simple project involving a Raspberry pi and some switches. I would never thought I would have any problem for something as simple as a switch, but here I am. The 2 wires from ...
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2answers
61 views

Influence of copper thickness on interference between PCB tracks

Explanation : I have designed a PCB for motor control. On this PCB there is a power part and a logic part. The power part is composed of MOSFETs, MOSFET drivers, hall sensor for current feedback and ...
3
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1answer
67 views

GSM Interference with Meanwell Switch mode PSU

I am having trouble with interference from a GSM modem and my switch mode PSU. I do not know much about interference and how the radiation patterns works for GSM. Below is an image of the circuit ...
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1answer
33 views

Digital Counter signal oscillation

I've a digital counter (Kubler Codix 908) with integrated 30Hz interference input filter integrated, but sometimes (when the contact that will increment the counter is closed) it counts two pieces... ...
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votes
1answer
97 views

GPS L5C Differential? Max Update Rate(bits/s|Hz)?

The differential GPS chips use L1 and L2C to calculate the ionospheric interference. With the new GPS satellites, the new band L5C is being deployed, and I am wondering about the following things: ...
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1answer
74 views

PC monitor flickers/resets when washer motor switches on or off [closed]

My room is next to our laundry and I've recently got a new PC monitor. I've noticed each time the motor in the washing machine is switched on or off, my monitor flickers/resets. The monitor is 32" but ...
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0answers
44 views

magnetometer affected by vertical motion?

I have 2 separate tilt-compensated magnetometer setups. One is an Invensense 9250, the other is a simpler LSM303. All I'm trying to do is compute a tilt-compensated compass heading. I've taken both ...
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1answer
485 views

Electrical noise resets & chattering in relay modules using ESP8266

I am trying to build my own SONOFF like device by using a Wemos D1 mini and associated circuitry. I am facing an issue with electrical noise where whenever switching of the relay causes chattering ...
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1answer
62 views

can a PC parallel port produce interference?

Please forgive me for crossing wires on top of IC's but I wanted to get things done, yet still have no luck. Let me explain the circuit. I created a circuit in which three parallel port data lines ...
6
votes
1answer
412 views

Help review my first arduino PCB: What did I do wrong? [closed]

EDIT: After taking all what you guys said into account, I edited the pcb into the following. Changed the FTDI while breaking the ground loops and working on the traces a bit, changed the size of the ...
3
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1answer
256 views

Transformer vs capacitive vs both coupling to speaker

I have seen various configurations in my lifetime on how an 8-ohm output speaker is connected to amplifier circuits. Currently I'm doing a project using an LM386 amplifier and I capacitor coupled ...
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1answer
32 views

Can a bilateral switch block transmitter interference and can my board still produce great audio?

I made a circuit in which an ISD1760 chip outputs music via an LM386 IC and I like the quality and volume of sound, however, when I run an HM-TRP transmitter on the same circuit board and the ...
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2answers
503 views

Metal detector coil SHIELDING?

Many designs of coils, of metal detectors, are shielded (Faraday shield). Should this be used in a gravity-fed detector (like the sketched one)? What's the shield for? NOTE: The coils are arranged ...
0
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1answer
45 views

Would any voltage be induced in this scario due magnetic coupling?

Imagine a source with a 100 Ohm source impedance is coupled to an amplifier/receiver which has 1Meg input impedance and the transmission is done by using two parallel wires signal and return |XA| and |...
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2answers
570 views

Shielded cable, to ground or not, in amplifier

I have been looking for an answer on the net about this question but not found it fully answered. The topic has been up here a few times (see links below) as well but I find the answers lacking. My ...
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0answers
39 views

Maximum Bluetooth LE devices near each other

I am planning to put 100+ Ruuvitag beacons(Bluetooth LE tranmistters) in a ~120m2 area. There will be approximately 1 meter distance between devices. I need to get their advertisements at once(each ...
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1answer
37 views

powering 2 DC motors

I have two 2.5A 12V DC motors running fans at high rpms. When I hook up one to my 10A 12V DC power supply it works great. When I hook both up the motors just pulse, turning a revolution or two every ...
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1answer
90 views

PMR446 interferes with small electronics?

Some small electronic devices react to PMR446 adversely temporarily, when exposed to a PMR446 transmitter, during the transmission. Portable DVD player: Green horizontal stripes on screen. Increasing ...
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1answer
51 views

Experimenting interference effects for different measurement systems

This is about for low level signals interference/noise being observed with single ended data acquisition inputs but not with diff inputs. Basically there are three data acquisition boards, where one ...
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0answers
134 views

8051 programmer not working when laptop lid removed despite suggestions in comments

UPDATE I took a suggestion of disconnecting my external monitor from my laptop and the results were the same. What I did notice however is that the AT89S52 chip always reports the correct signature ...
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2answers
106 views

Human Interference in Signal Circuit?

I've run across an interesting problem with a device I'm building. It seems that when I put my PCB into its plastic enclosure, I can create some signal simply by tapping the case. What makes this ...
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2answers
113 views

FM radio Interference

Near to my location we have IAF(Indian Air Force - Tambaram) training center is there, While hearing FM radio at a at frequency of 106.4MHZ I can hear the cockpit commands/voices daily when these ...
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2answers
66 views

Is this warning about wireless modules interfering with aircraft systems true?

I see the following warning for Sierra wireless (cellular) modems: Do not operate the Sierra Wireless modem in any aircraft, whether the aircraft is on the ground or in flight. In aircraft, the ...
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1answer
58 views

How to model this scenario/circuit with 50Hz interference?

There is an industrial amplifier for force transducers. It amplifies strain gauge outputs and outputs voltage. Lets call this as a voltage source Vtrans. Its output is around 50 Ohm. I measure it ...
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2answers
156 views

relays interfering each other

simulate this circuit – Schematic created using CircuitLab Hi: I have 3 relays (230V coil, 2 contacts) in a system, all the coils 'returns' are wired together, while hots come from the various ...
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1answer
68 views

How to work out the interface of an LCD?

If I got an LCD, and I didn't know anything about it, and there were no markings on the pins, how would I go about interfacing with it? For example, I got this small (around 2.5") colour display out ...
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0answers
82 views

Trying to find the signal in an AC line

I have a medical office call box/light system that is older probably 20 year old and they moved the main panel that the Drs see to know when there are patients waiting and since they moved it, it is ...