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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2
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3answers
170 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 ...
0
votes
0answers
37 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 ...
1
vote
1answer
78 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
votes
1answer
68 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 ...
0
votes
2answers
46 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
52 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 ...
2
votes
2answers
108 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 ...
3
votes
1answer
90 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
votes
1answer
159 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
108 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
170 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
votes
0answers
299 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
140 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
221 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 ...
0
votes
0answers
319 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
3answers
919 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
128 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
votes
2answers
184 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
900 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
918 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 ...
1
vote
2answers
504 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 ...
7
votes
2answers
1k 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 ...
8
votes
2answers
471 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 ...
8
votes
2answers
628 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
2k 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
3k 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
536 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 ...
1
vote
3answers
452 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
votes
4answers
477 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
957 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 ...