Current flowing between two distinct references which are assumed to be at the same voltage, but in fact are not; typically this current flows through unexpected or undesired paths

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1answer
57 views

Loops in ground planes

Working on a PCB layout and just did some ground plane pour. From working with tube amplifier designs I know that a good star shaped ground design helps a lot to keep hum out of the circuit. Ground ...
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2answers
93 views

unbalanced audio - shielding and ground loop for 2 ch

I have a 3 conductor wire that are all wrapped in a foil shield with wire conductor, for a total of 4 wires. I am connecting the 3 inside wires to audio left, right, and ground. This is an unbalanced ...
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1answer
32 views

PWM Return Problem

A controller send pwm signal with 2 wires 1- PWM 2- PWM Return But servo motor has 1 input pin. So is it correct to use servo supply return (28v Gnd)or servo chassis input for controller pwm return ...
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3answers
127 views

How safely to send signal between logic and higher current pcb?

I'm designing a PCB with 4 FETs. These are driven in the same board by totem pole drivers, and their load are about 5A total. I am using PWM at 1000Hz. The signal comes from a logic IC in another ...
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1answer
97 views

Arduino/Netduino: connecting a second power supply's ground to GND pin

I'm planning to play around with an addressable LED strip and a Netduino, and having read some tutorials I've learned that I will need an external power supply to provide enough current to the LEDs. ...
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3answers
412 views

Ground Loop? Noise from 12v to 5v converter manifest in bluetooth audio source

I've created a custom, bluetooth audio harness for my Jeep WJ using off the shelf parts. Amp - Clarion XC1410 Converter - 12v to 5v buck converter Bluetooth Audio - Logitech Wireless Speaker Adapter ...
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2answers
148 views

Oscilloscope measuring of PMT in photon counting mode

I have a setup as drawn below: DC source of 15V connected to high voltage (HV) source of 1500V connected to photomultiplier tube Hamamatsu, R1-R3 are resistors builtin the socket of PMT (there are ...
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votes
3answers
538 views

Does a Connector With Multiple GND Pins Make a GND Loop?

There are some cable standards that have multiple GND pins on the connector proper. A good example of this is the SATA connector (it has 3 of them). In reality, each GND pin has a slightly ...
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0answers
28 views

Hum/buzz noise in audio system

I have crazy experiment about hum noise problem. I have ferrite transformer to eliminate noise from hum noise , not succeed ,than i use metal E-I transformer ,there is no hum in system. I could not ...
8
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1answer
652 views

Why is this resistor connected between connector shield and ground?

I was looking over my raspberry pi model B and I noticed a resistor between the USB power connector shield and ground. I've noticed this on many PCB designs with much larger packaged resistors ...
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2answers
78 views

Are there other ways in which 60Hz noise can get into your system?

Are there are other ways in which 60hz can get into a system other than ground loop ?
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1answer
320 views

Single point vs Ground plane, in audio OP AMP PCB layouts

Recently I had posted a seemingly innocent question on another forum. I was trying to keep a small and relatively simple circuit down to a 2 layer board and was asking about the shielding merits of a ...
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1answer
82 views

Can we consider that ethernet or RS-232 (RS-485) networks have no ground connection between the two ends of each cable?

This is for a huge home theater. I have a power transformer that converts 380VAC between two legs of a 3-phase power system down to 230VAC, with a center-tap of the secondary being our "neutral" for ...
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1answer
174 views

DIY wifi radio radio NOISE!

I am building a mono, internet enabled, WiFi radio and I have a problem. I am running into what I believe may be a grounding issue. When I turn the system on, I hear all kinds of noise coming from ...
0
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1answer
196 views

Should I worry about ground loop in power supply circuit for 3G modem or WiFi?

Can someone explain clearly what is ground loop and when we should worry about it? Shall I worry about it when I connect two USB wires in parallel to deliver power to my 3G modem? I have something ...
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votes
5answers
361 views

Properly grounding 2 MCUs using I2C

I'm building a mechatronic system that consists of 1)XY Gantry controlled with PIC32 and a DIY motor shield and 2)control box with PIC24 three potentiometers + room for expansion, typically located ...
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0answers
158 views

Can this op amp circuit easily be modified to provide differential input?

I have a "noisy ground" problem which seems to be essentially the same as the one described in this old post: Ground loop? Switch mode power supply noise The solution (as provided in the answers to ...
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0answers
95 views

Ground loops on single trace in the middle of a ground plane

I'm trying to optimize the layout of a MAX1979 TEC driver on a double sided PCB. Is the placement of single, small traces in the middle of a ground place, as seen below on the bottom side of the ...
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1answer
63 views

Why a ground loop a problem, not a ground plane(patch attena)?

The question is as the title says: I see various material saying using a solid ground plane. Why would not that be a problem, since a solid ground plane could be a patch antenna?
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3answers
199 views

loop area and EMI

I always hear something like "reduce the loop area" when reading materials on EMI reduction. Why we need to minimize the loop area? I have two guesses: Smaller loop area will influence less signal ...
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3answers
401 views

Ground loop when measuring in process pH

I have been experiencing a very difficult to solve ground loop problem with my pH measuring system. My basic setup is a standard pH electrode running through an op-amp to an ADC which communicates ...
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0answers
82 views

Grounding problems connecting two evaluation boards

My setup is as follows. I have a Xilinx FPGA KC705 eval board with a daughterboard attached. I have a set of 6 wires going from headers on the daughterboard to the header pins on an audio codec eval ...
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1answer
110 views

What is this Circuit's function? Does it involve Isolation?

My question is: Does this circuit isolate the "X Volts" lines from ground (1) If not, how should I implement an opto-coupler to provide isolation between the data lines ("X Volts") and ground? ...
2
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1answer
336 views

How does a first-timer set up a correctly-grounded workbench / work-station?

I'm new here, and new to electronics in general. (for the most part … my [awesome] father had me building some simple robot-kits with him when I was a kiddo, but I'm getting into it “4srs” for the ...
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2answers
262 views

RS485 + Power over twisted pairs, still need isolation?

I need to communicate with a piece of hardware on an elevator car. I have a few twisted copper pairs available, but it's not CAT5, so Ethernet is out. Instead I'd like to use RS485. I've been ...
4
votes
1answer
159 views

Wiring multi node devices with i2c

I wanted to confirm that my approach is correct for wiring multiple devices together communicating over I2C when each node is utilizing DC\DC converters. Should I be including a ground connection over ...
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2answers
228 views

Ground Loop for balanced connection

Different articles and tutorials covers somewhat contradictory information about ground loop. For a balanced connection (differential), the return path is the other differential pair, however ...
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1answer
216 views

Proper power design for a USB device

I'm designing a USB device that I want to be powered eintirely from a wall wart and have a couple questions concerning the power connections and ground loops. 1) If I connect the USB GND pin to ...
0
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1answer
771 views

How can I reduce hum & pop from simple amp setup?

I am building a bluetooth speaker and am encountering two issues. Here is my setup so far: When turned on, it gives two very loud POPS before working normally. Is there a simple way of delaying the ...
6
votes
1answer
284 views

How to avoid a ground loop between pcbs

There is an enclosure with 2 separate pcbs. Pcb A amplifies a mV level signal (10Hz to 100kHz) coming from an external sensor. The amplified analog signal is sent to pcb B, which digitizes it and ...
3
votes
2answers
855 views

Can I use ferrites for the ground connections?

I may have an issue with conducted EMI through the ground connections between devices in a system. There is specifically a device which clearly creates noise on the measured signal from another ...
0
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0answers
611 views

RS232 Ground-Loop Isolation: “creative” solution?

I have a RS232 connection that seem to suffer from different ground potentials at the two ends of the connection: The receiver signals a "break condition" in Realterm. As I understand it this means ...
2
votes
1answer
187 views

What is return current of crystal oscillator?

I belive that every signal on the PCB has its return current. One layout hint for crystal oscillator is that "The ground connection for the load capacitors should be short and avoid the return ...
3
votes
1answer
299 views

Inter-PCB Ground Loops

I have designed a mezzanine PCB that will sit on top of a main PCB connected via two connectors on either end of the mezzanine PCB. If I connect the grounds on at both connectors (And thus at both ...
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0answers
487 views

Separate grounds on connector. Common ground plane on PCB?

Further to this question: Best way to group power pins on a connector? where I was advised to keep the ground pins for different power supplies separated on the stacking connector. And bearing in ...
4
votes
4answers
2k views

Ground loop problem with Power over Ethernet

I am trying to build a weather station, powered using Power over Ethernet. Originally I planned to use a Nanode as the microcontroller, but since the Raspberry Pi is so cheap, I decided it was much ...
0
votes
1answer
154 views

SMPS power supply shows strange AC voltage output

Hi I have been using a simple laptop power adapter (15V) for my electronic lab-works. And today I'm troubleshooting some RF circuits, and I found a little guilt about ground loops, So I check ...
0
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2answers
210 views

Should old electronics be polarized?

On old electronics that don't have a polarized power cord, what would be the benefits of adding a 2.2Mohm resistor from one side of the a/c to the chassis and switching out to a polarized cord ...
8
votes
1answer
2k views

To “ground fill”or not to “ground fill”?

I have been reading up on the EMI issues in Electromagnetic Compatibility Engineering by Henry Ott. (wonderful book btw). One of the topics "PCB Layout and Stackup" (aka Ch 16) there is section about ...
3
votes
2answers
2k 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 ...
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2answers
796 views

USB port and bench power supply ground difference

So I recently coughed up the $250 for a semi decent bench power supply, the thing that got me though is when powering a circuit from this unit and connecting the BusPirate via USB is that the ground ...
8
votes
3answers
3k views

Why we use ground

I have been wondering this for a while, so I did some digging, and as usual, wikipedia was the most illuminative. It looks like the telegraph was the first time ground was introduced to complete a ...
9
votes
2answers
632 views

Shielding and Ground loops

I have various pieces of equipment that all need to be connected to GND (Chassis GND). The issue I'm having is that I'm connecting an ADC card inside a computer through a metal box with custom ...
9
votes
2answers
872 views

Grounding of ADC grounds

Fast, high resolution ADCs, especially ones that have parallel output, usually have a separate supply pin (DRVDD, (drive vdd) or OVDD (output vdd)) presumably because they don't want to couple noise ...
4
votes
1answer
3k views

Dc isolation (transformer?)

I need to isolate the dc input from the dc current inside the circuit (both 9v), in the same way as a 1:1 transformer isolates the AC current inside the circuit from the input AC. I already found out ...
3
votes
3answers
5k views

Ground loop? Switch mode power supply noise

I have a single 12V supply powering a 12V class D audio amplifier (Tripath TA2020 based, model 'SMSL SA-36') (C) and a very cheap 12V to 5V 2A rated switch mode converter (A). The 5V is used to power ...
2
votes
2answers
768 views

Connecting Different Devices via RS232 - Worried about Ground Loops

This is sort of a follow up to my previous question regarding power supply for my telescope. The general advice I got was that I should just ditch regulation and connect the lead-acid battery directly ...
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3answers
528 views

Do I have a ground loop or another problem?

Okay, I know this is an electronics Q&A site, and this question is mildly computer related. But I've got this problem with my VGA monitor, a graphics card and a computer. The problem is the video ...
9
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4answers
544 views

Communication between microcontroller and separately powered PCB

On one board I have a microcontroller with one power supply and on another I have a Flip Flop with a separate power supply. I want to connect a pin of the microcontroller to the reset pin of the flip ...
4
votes
1answer
1k views

Isolation Transformers (Capacitive Coupling)

In my application I have an issue with ground loops and to solve this I require to have devices isolated from their drivers. The system operates with a 13.56MHz signal and a wide bandwidth is not of ...