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

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grounding 2 different power supplies

I have 2 circuit boards I'm trying to connect together that each have a common 24 VAC source they are connected to. The problem I have is I'm trying to feed a switching 12 VDC signal to the one board ...
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1answer
69 views

Ground and power PCB layout for MCU

As you know most of the MCU's has several Vdd and Vss pins. In the case of two-layer PCB it seems convenient to use some polygons beneath MCU (like on the figure below). The first option is treat the ...
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1answer
40 views

SCR triggering and ground loop issues

I am trying to trigger an scr/thyristor from a 0-5V TTL pulse (channel 1 on the oscilloscope output). The schematic can be viewed below. I am using the TTL to pull the 2n2222 transistor 'on' which ...
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2answers
288 views

Grounding unused leg of bussed resistor?

I've got a bussed resistor: The package I'm using has 13 inputs and 1 output, tied to ground. I'm only using 11 of the inputs. Do I need to worry about the floating end of the two unused inputs? ...
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2answers
79 views

Variable Voltage Using PWM and Low Pass Filter

I am trying to control a steady DC output voltage using a Micro controller with a PWM duty cycle. With the current schematic, the Voltage on Vout is pulsing along ...
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1answer
38 views

Arduino Ground reference plane

There are three GND pins on the Arduino UNO pinout. As I'm trying to design a mixed signal PCB to act as an Arduino Shield, I wonder how I should connect those pins, i.e. to the analog or digital ...
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1answer
36 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
118 views

Two Five-foot Ground Rods vs. One Ten-foot Ground Rod

I am thinking about installing two five-foot ground rods in place of one ten-foot ground rod. What would be the relevant comparison(s) and contrast(s)? Let me know if you need further information. ...
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1answer
57 views

Can I connect all ground connectors via the ground fill?

I am working on a very, very simple two-sided PCB design that connects one 8-pin header with 6 audio jacks, each of which has its right channel and ground connected. All grounds are connected via ...
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1answer
63 views

Question on capacitive circuit in practice

If we were to build a circuit, let's say with a power source of 120V AC going into a transformer which steps that up to 10kV @ 30mA, the output of which would be connected to a capacitor with a ...
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3answers
98 views

How to deal with grounding and the capacitors in this opamp schematic?

Here is a schematic I'm planning to make (right click on the image and 'open image in new tab' to see it better'): I have a transformer and AC to DC converter that makes +/-12V. (1) Does 'power ...
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1answer
81 views

How to implement grounding into this electrical circuit?

I'm trying to make some tutorials but I have no idea what should I do when I see the term ground (GND). Here is an example: I want to know how I build the GND part. Where I connect it? Also, if ...
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1answer
97 views

Laptop surface vibrating when rubbing over it [closed]

Because my previous HP laptop adapter stopped working, I got a new one. But if I use this one, I feel a kind of vibration when I rub over my laptop's surface. I don't have this if I work on battery, ...
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84 views

Connecting grounds of following circuit

simulate this circuit – Schematic created using CircuitLab I am using 5V supply derived from rectification of 230V AC and using 7805 IC for DSP while I am using 0-300 V DC lab bench type ...
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2answers
65 views

Binding LM4871 audio amp output to another circuitry with ground referenced input

I using LM4871 as a audio pre-amp in my device. If I let the output to earphones or external speakers then it works great. If I want to loop LM4871 output (pin 5 and 8) back to one of the local audio ...
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1answer
32 views

MCP41100 Power supply and grounding ? Analog ? Digital?

I'm thinking of using an mcp41100 digital potentiometer to control an op amp gain. My board will have a split ground plane - digital and analog grounds. Unfortunately the mcp41100 doesn't have ...
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3answers
77 views

Grounding a Device And/Or Room

Hoping this is the correct exchange. At the moment I'm currently renting my house in Canada (120V), and it seems the landlord has attempted to try pull a fast one. From what I understand, or possibly ...
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1answer
233 views

What to use as a ground in a plastic, mobile container

I'm building a basic stereo system, using a car stereo and speakers, inside a large plastic box. The stereo requires grounding, but the box is entirely plastic, so there is no metal chassis, and it ...
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2answers
84 views

Obtaining O-Scope signals in a AC/DC supply - grounding issues

I need to check waveforms in the power supply from this design reference by Texas Instruments. I essentially built the supply, but it is not operating correctly - ie, no output current, but it has ...
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1answer
60 views

Audio oscillator cross-talk on small synth project

I am making a small 9V battery powered synthesizer with a square wave oscillator built around a 40106b Schmitt trigger (reference: http://richdecibels.com/blog/?p=11) and a few other components, one ...
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0answers
57 views

how many “Resister/ cap network” between PE (shield) to Ground are necessary?

In our set-up, there are 2 backplanes and both are interfaced with each other using cables. Each backplane has multiple RJ45 connectors and SubD connectors (which are used for data transfer between ...
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2answers
72 views

Kirchhoff's Current Law at the ground node?

Can one do KCL at the ground node? Does any current go into the ground? I think not, but I am not sure. Bonus Question: If yes, then how does grounding buildings drain the current into the Earth?
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4answers
2k 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 - ...
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52 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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2answers
149 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 ...
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1answer
142 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 ...
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2answers
136 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 ...
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4answers
194 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 ...
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1answer
48 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 ...
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1answer
122 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
59 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 ...
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2answers
101 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 ...
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2answers
94 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 ...
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1answer
136 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 ...
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1answer
164 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 ...
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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 ...
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1answer
124 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 ...
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2answers
129 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
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2answers
196 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 ...
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1answer
187 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 ...
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2answers
331 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
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3answers
252 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 ...
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5answers
371 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
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1answer
369 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 ...
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3answers
293 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 ...
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1answer
101 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
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0answers
155 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 ...
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1answer
107 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? ...
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1answer
195 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 ...
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1answer
166 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 ...