13
votes
How many "grounds" are there and what is the difference?
There are infinitely many ground symbols, as you can call anything ground. On some projects I have seen GNDA GNDB GNDC... etc.
A ground is a common reference voltage. No ground is truly 0 volts, but ...
- 77.9k
9
votes
RS 485 ground signal and chassis
Looks like a common mode voltage problem to me. Although differential signalling, it still needs a common GND.
(source)
Replace your 1nf 500v capacitor with a jumper. Or wire signal ground to all ...
- 22.3k
7
votes
Accepted
Is it better to connect ESD (TVS) Diodes to chassis ground or signal ground?
For ESD events, these disturbances will appear referenced to chassis ground so surge suppression should be between the incoming +5 volt DC and chassis ground but, it's quite likely that you will need ...
- 443k
6
votes
Accepted
What are these kinds of pins called?
Impossible to tell by sight, but they could very well be "Magnetic Self Locating" connectors. As with many other things, used by and popularized by Apple, but not invented by them.
Just wild ...
- 14.4k
6
votes
When does a PCB require a chassis ground connection?
The short answer is, the PCB should always have a chassis ground connection somewhere, having it float is not a great idea. If there is no ‘chassis’, there should be some kind of shield ground that is ...
- 51k
5
votes
Accepted
Chassis ground on Ethernet RJ45 Connector
The capacitor provides a low impedance path for RF currents between the cable screen and ground.
To be effective in reducing radiation from the cable, the screen needs to be connected to the chassis ...
- 7,671
5
votes
What are these "X"s / crosses on this schematic's wiring? Traces attached to the metal housing (ground)?
Based on the more complete schematic it seems fairly obvious that the continuous line around the outside represents the metal shielding can.
The X's seem to be where circuit traces or connectors ...
- 383k
5
votes
Accepted
Old Variac -- chassis ground? is it safe?
I don't see any connections to the case. There should not be any connections to the case.
Assuming there isn't, you should run the ground wire to the case and to the output receptacle. You can drill a ...
- 383k
4
votes
Right way to couple DGND to Chassis ground
Typically mains ground is your best bet, assuming that the connection to ground is good (in the building) and the wiring in the building is good, it's as good as you can get. A ferrite on ground will ...
- 77.9k
4
votes
Accepted
Extra 2 DB9 pins connection
They're the two sets of pins leading downwards on the sides of the connector.
Is it connected to chassis ground or is it an NC just to provide more stability for the mechanical and vibration ...
- 48.4k
4
votes
Accepted
ESD Protection on Un-grounded Chasis
Should I be doing the above step as the chassis is effectively not grounded?
Chassis ground is to protect against faults (shorts from power inside of the box to itself) and ESD. With low voltage DC ...
- 77.9k
4
votes
Old Variac -- chassis ground? is it safe?
IS this design safe?
If this variac has only a two prong plug, and there is a connection between one of the prongs and the chassis, then the chassis is at neutral, not at ground.
IMHO, this is NOT ...
- 20.7k
4
votes
What are the drawbacks of connecting circuit GND and Chassis via multiple mounting screws (for EMC and Safety)?
A system having a diagram shown in the question body is under the scope of IEC Class-I. This defines that no current (except the fault current(s)) should flow through the chassis to the earth because, ...
- 30.2k
3
votes
Accepted
If current flows through lowest resistance path, why circuits with grounding still work?
Current flows through ALL paths available.
If the circuit source itself is not connected to ground somehow, you will not be completing a circuit, so no current will flow through you no matter where ...
- 46.5k
3
votes
Accepted
Why not connect battery negative to chassis?
Using the chassis as a common ground is a typical method used in many applications and if done correctly is generally acceptable.
Two things to watch for however.
Grounding straps should be used ...
- 46.5k
3
votes
What are these kinds of pins called?
Looks like they are custom made using spring loaded pins such as the ones Mill Max makes (commonly referred to as pogo pins). Check out products from Cotelec too. I think they make something similar.
- 1,330
2
votes
Accepted
Chassis grounding short circuit
so how does the earth ground help on the enclosure ?
An earth grounded enclosure is there to protect you from an internal electrical short inside the enclosure.
If the enclosure has a proper Earth ...
- 3,333
2
votes
Accepted
What could happen if a lightning strikes a car with a battery connected to the chassis ?
The lightning can cause a fire regardless of the battery being connected. It can go through the electronics to the battery positive as well. A lightning strike on a solid car can blow electronics, ...
- 72.8k
2
votes
Accepted
circuit ground vs chassis ground
Assumptions: It seems that the output of the configuration you have drawn there is a 24V DC signal that is +12 on and -12 with respect to circuit ground. There is a circuit ground from what appears to ...
- 153
2
votes
How do you avoid mixing CHASSIS GND and sensor GND when reading a sensor?
Lets examine a realworld design: a robot with several powerful drive motors, and an instrumentation system that monitors the motor bearing temperatures to detect wear and misalignment to predict ...
- 33.8k
2
votes
Accepted
SMPS chassis ground and earth ground
The basic art of the quiet SMPSU (Or pretty much anything else which oscillates!) is to keep the loop areas as small as possible, "Star" earthing is for low speed stuff where the big concern is power ...
- 17.4k
2
votes
Accepted
When to choose Class I vs Class II AC to DC power supply?
In your case, the Class I will force your device to be Earth referenced. That can be necessary for some signal level compatibility with other devices. Or can be bad for the same reason.
Neither will ...
- 19.6k
2
votes
Amplifier chassis noise when not earth grounded
When you use a floating-DC supply, your device will literally float in the winds of EMI. If you connect more floating devices with the signal lines, then you form a large messy monster with long ...
- 19.6k
1
vote
What are these "X"s / crosses on this schematic's wiring? Traces attached to the metal housing (ground)?
You've cropped the schematic too much and haven't included a hyperlink to the source.
Noting that the power jack breaks that line it appears to be either the case or the edge of the PCB. As the ...
- 171k
1
vote
Connection between Chassis GND and Circuit GND for ESD/transients
Looking at figure 14-14A, I think there must be additional unidirectional TVS from GND to PWR, and probably a ferrite. The data lines typically get a small CM choke, sometimes series R (often built ...
- 1,227
1
vote
Accepted
Plane Chassis Grounding
An evolving answer
Go study Faraday cages. The plane's metal air-frame acts like a Faraday cage. If that doesn't provide an answer, please explain why it doesn't. Maybe draw a picture so that it's ...
- 443k
1
vote
How do you avoid mixing CHASSIS GND and sensor GND when reading a sensor?
If your sensor has own GND, it also should have a own VCC. Most car engine controls have a seperate 5V pin.
If you use sensor GND and normal 12V VCC then use a big capacitance.
If you want to ...
- 364
1
vote
Is there a colour standard for mains 'signal' wiring?
No it varies by country and voltage:
Wiring Color Codes Infographic. Released under the Creative Commons Attribution-ShareAlike License
- 77.9k
1
vote
DMX chassis(?) pin?
Ok, so this thing is a fully isolated DMX splitter, in which case you have a few choices to make.
If you are using a metal case then the choice is made for you and all of the connector shells are ...
- 17.4k
Only top scored, non community-wiki answers of a minimum length are eligible