Problems related to the connection of circuits to ground or earth references. Can affect safety, accuracy, reliability and interfacing.

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9
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4answers
1k views

Where is the ground/negative for overhead power lines?

I recently learnt that ground can be used to complete circuits using high voltages. I'd like to know if this is how overhead powerlines work, and if so where exactly do the cables/circuit terminate - ...
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
2answers
126 views

Simple circuit reacts to touching a node

I am trying to repeat a circuit from this post. For some reason it does not work properly, and trying to fix it I figure out strange behavior. LED turns on if I touch R3 with my finger or with ...
1
vote
0answers
96 views

Capacitance of two wires with a grounded wire between

I have measured the capacitance between wires number, say, 1 and 3. With the wiree #2 just floating, the result was 390 pF. But after i have grounded the wiree #2, the capacitance was 220 pF. What is ...
-1
votes
2answers
72 views

Constant current led drivers shared ground

I have 4 constant current led drivers with PWM. Here's 300-1500mA LED Driver datasheet. I want to use 3 of these drivers to power each color of a 90w rgb led. I was under assumption that I could ...
1
vote
4answers
157 views

Why use 2 isolated grounds in Mackie 220W Power Supply?

I recently took apart a Mackie 220W power supply for an analog sound board. Much to my surprise I found the following scheme: Earth grounded: 48V -18V 18V Seperate, isolated ground: 12V 5V I am not ...
0
votes
1answer
41 views

Using Ground Off Another Circuit [closed]

I have a power outlet without a ground, but I have an electronic device which requires a real ground (can't use a GFCI protected outlet). Would it be okay to run an extension cable from an outlet ...
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 ...
1
vote
2answers
52 views

Grounding a conducting object

Is it possible to trap some electricity in the object even though the object is grounded? For example if we ground a conducting sphere over a resistor, will all electricity leave the sphere once it's ...
2
votes
2answers
70 views

Via through TQNF Exposed Pad

Is it ok to use an "ordinary" via to connect the Exposed Pad of an TQNF package to ground, as shown in the following picture? I am using eagle. DRC generates an "overlap" error, is it ok to ignore ...
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 ...
-1
votes
1answer
121 views

Grounding Plexiglass

I have a sheet of plexiglass that has metal strips (Aluminum) that will be connected through wires to an Arduino. The Arduino is grounded but the metal strips are not. The metal strips will rest on ...
3
votes
1answer
94 views

Question about analog and digital ground planes

I am using a microcontroller with an integrated DAC. On my 4 layer PCB, I have connected the digital and the analog ground planes below the microcontroller. The microcontroller and the DAC are ...
18
votes
2answers
1k views

Why does connecting a high-current device to my digital circuit cause weird behavior?

I have a arduino microcontroller other digital thing and when I connect a motor pump heater other high current thing I experience weird ADC measurements reboots crashes errors in digital ...
1
vote
1answer
84 views

Would I need a star topology with a dedicated ground plane?

Some background: I have a PCB with a bunch of relays on it. The purpose of the circuit, is to allow signals to pass through from one connector to another (db37), or to stop it - that's where the ...
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 ...
2
votes
2answers
166 views

3 SMPS in one board

I'm doing a PCB where there are 3 SMPS: one boost(12v to 48v, 1 amp max) and one buck converter(5v to 4v, 4 amps max) functioning at the same frequency(same timer in microcontroller). the other ...
1
vote
1answer
144 views

How to safely use the power-socket ground for the anti static wrist strap?

I saw as practice to use the power-socket ground for the anti static wrist strap, I saw this done where there is no available specially designed ground for anti-static pads and bracelets, but this may ...
14
votes
2answers
281 views

Grounding PCB to enclosure

I am designing a small sensor which fits into a custom aluminum enclosure. The sensor uses CAN bus and a long cable to connect it to the host and power. The shield of the cable will ground the ...
2
votes
3answers
198 views

Using an OEM power supply

I am trying to use an 12V OEM type power supply to supply 12V to stepper motors through an L293 h bridge in an Arduino powered circuit but my current setup starts burning all the negative wires and ...
1
vote
5answers
271 views

Why can't you use the ground of a second DC power supply as a return?

This is probably a really silly question, but I can't seem to find the answer anywhere. Say I have two totally separate DC power supplies running from AC power, and another piece of equipment that ...
9
votes
1answer
328 views

What is mecca ground?

I came across few different ground names (digital, analog, signal, power, mecca, EM, shield, etc). I do understand most of them - but mecca is a new one for me. Can someone please explain me this ...
8
votes
3answers
227 views

Coaxial cable signal and ground

How does a coaxial cable carry RF, audio and low freq. signals? I understand there must be a difference between all these, for example the return path being through the shield or not. Can someone ...
-1
votes
1answer
87 views

Exclude GND trace from GND groundplane in Eagle

I have a board layout in Eagle with a groundplane. Now I have a trace inside of this groundplane which is also GND but this one shouldn't merged into the groundplane. The reason is, that i want to ...
0
votes
0answers
136 views

Connecting Raspberry Pi GND to GND of external source

This is probably a very basic question but the concept of GND always confuses me. My setup: Raspberry Pi connected with MicroUSB to a power supply. External circuit supplied by an ATX power supply ...
0
votes
1answer
106 views

Is grounding needed when using adapter to phone?

I am doing research on an audio plug. I wonder, is it a must to connect grounding circuit from handphone to the earphone if we use an adapter (image 1). Or can I do the connection like in image 2? ...
4
votes
1answer
175 views

Why bridge the GND wire on a DE-9 connector?

Why would someone want to bridge the GND wire to the metal shield of a DE-9 connector? Take a look at the picture below. A 10 position flat ribbon cable is soldered to a DE-9 connector (male). On ...
1
vote
1answer
154 views

UART receive only works if I have a oscope or voltmeter attached to it

I designed a board to interface the CEL MeshConnect Mini Zigbee module with a lighting controller board. The Zigbee module is able to transmit bytes via UART and I've verified this, but the radio ...
4
votes
2answers
777 views

Positive and negative potential via two power supplies with common ground?

I need to use a positive and negative potential on a circuit including an instrumentation amplifier. My lab only has single supply power supplies (only offers positive voltage). I know that I can ...
3
votes
2answers
224 views

Why is this laptop adapter grounded?

This adapter is clearly not capable of delivering a null, a power and a ground to the laptop because the connector only has two surfaces. The adapter itself is plastic. So why is it grounded? (Note ...
4
votes
1answer
278 views

Surface Pro grounding issue

I have a Microsoft Surface Pro tablet which, when charging from the included power adapter, gives a slight tingling feeling when touching anywhere on the Magnesium shell. This is a commonly reported ...
5
votes
1answer
158 views

Why do some devices have 200V on the case?

I recently got a desktop LED lamp, and I feel a "strange" slight vibration when touching the metal case. I found that other devices also have high voltage on their case. What is the reason/trade-off ...
1
vote
3answers
205 views

How bad can an unconnected ground be?

My collegue here has two seperate boards linked by an SPI link. He just asked me: "So... you need to connect the grounds?" After I picked myself off the floor and answered very much in the ...
2
votes
0answers
81 views

Ground coupling a high voltage source with the A_GND and D_GND

I have a device that measures the current in the mains through a 0.01 Ohm 20W shunt resistor. The voltage across the shunt is amplified by a op amp and feed into a uC's ADC for farther calculations. ...
3
votes
1answer
201 views

What is a 'quiet ground' / 'Ground plane'

I really don't expect an analytic answer. I'm sure there are far too many variables to consider. I'm working with a fairly simple circuit (Precision voltage, Instrument amplifier) but need to really ...
1
vote
1answer
342 views

5V 1A from 24VAC transformer with grounded secondary

I built a power supply for a micro-controller board that requires 5VDC and peak of 1A (typically sits at 500mA). The power supply has an input of 24VAC. I used a bridge rectifier and an LM2575-5 ...
11
votes
1answer
360 views

Is it possible to reject noise traveling on the outside of a coaxial transmission line?

Say I have some ordinary coax between a receiver and an antenna. That coax will have three currents in it: the desired signal an exactly equal an opposite current on the inside of the shield ...
7
votes
1answer
412 views

Placement/routing of decoupling cap straddling oscillator guard ring on dsPIC

Changes in my design are forcing me to replace my 44-pin dsPIC33FFJ16MC304 with a 64-pin (same package size, finer pin pitch) dsPIC33FJ64MC506. In the datasheets for both chips, Microchip recommends a ...
3
votes
1answer
298 views

Oscilloscope ground clips sparks while connecting to power supply

Oscilloscope ground clips sparks while connecting to power supply ground. I do understand The clip is connected to earth ground. But why does it not spark when I am powering a circuit of the supply?
6
votes
4answers
584 views

How to handle unused wire in cable

What is the best way to handle an unused wire inside of a cable. Let's assume I've got a cable with 4 wires, only 3 of them are used. I could connect the 4th wire at one end to ground, at both ends ...
0
votes
1answer
219 views

How does this heavily oxidized copper-to-steel joint work in earthing?

Wikipedia article on grounding features this photo: Here's a close-up of the joint: Clearly the steel rod is heavily oxidized and the copper wire is oxidized. The clamp is coated with something ...
8
votes
2answers
738 views

Grounding and why charge leakage occurs

A basic nugget of info is missing in my end-to-end picture of how grounding works and why it's important. When a voltage is applied in a circuit the electric current starts flowing (or the field ...
0
votes
0answers
222 views

Oscillating op-amp due to grounding issues?

I am working with an op-amp as a voltage level shifter for a 'black box' piece of equipment. The circuit works by it's self, amplifying a square wave correctly but when it is connected to the 'black ...
6
votes
2answers
277 views

Grounding Metal Object to Eliminate Static Electricity Using Electrical Ground

let us say that I have built a metal cabinet in which I will be painting small objects. I am looking to eliminate any static electricity that could possibly build on the object to be painted or on the ...
3
votes
2answers
643 views

Ethernet phy connection: grounding between chassis, connector and IO

The phy chip I'm using has a evaluation board which grounds the chassis, connector and signal gnd points in the following way: However, I don't really understand why the MCTx connections are ...
6
votes
1answer
411 views

How is the following ground symbol different from conventional ground?

I've seen the following ground symbol in quite a few schematics: How is this different from the typical GND symbol?
8
votes
3answers
293 views

What do I do with the extra “ground chassis” tab on a DC power jack?

Product Link Datasheet I have about fifteen 9v wall warts within specs for the circuit; I'm going to use the one that fits the jack. There are three solder tabs on the jack. One for the positive ...
7
votes
2answers
377 views

Recommended way to connect the exposed pad to ground pins

Is it okay to connect the exposed pad to the ground pins as in the image below, or is there a recommended way to do it?
4
votes
2answers
5k views

How to safely ground a switching power supply with floating outputs?

I just received a 120VAC to 5VDC (20A) switching power supply (the kind with a passively ventilated metal casing) for use with a microcontroller project I'm working on (driving long LED strips). I've ...
2
votes
2answers
196 views

Can current be drawn from ground in a SWER transmission setup?

I am almost certain that this is a ridiculous question, but cannot figure out why this scenario would not work. From what I understand, current from the electrical station is distributed to houses ...