Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [chassis]

48 questions
133
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6 answers

Should chassis ground be attached to digital ground?

I'm working on a PCB that has shielded RJ45 (ethernet), RS232, and USB connectors, and is powered by a 12V AC/DC brick power adapter (I do the 5V and 3.3V step down on board). The entire design is enclosed in a metal chassis. The shields of the…
cdwilson
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Why are some mounting holes connected to ground?

Why are plated mounting holes connected to ground ? I read that if you are connecting your board to chassis ground, then it should be connected at only one point and connecting say 4 mounting holes to ground and then screwing them into the chassis…
efox29
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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 tip, one for the negative ring/sleeve, and one for…
dwwilson66
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How many "grounds" are there and what is the difference?

I stumbled upon many terms for ground, naturally as newbie I got very confused. ground earth chassis ground earth ground common ground signal ground Are there any more? I assume some are for AC and some for DC. What is the difference?
komrad2236
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What are the drawbacks of connecting circuit GND and Chassis via multiple mounting screws (for EMC and Safety)?

Although there are various suggestions around for how to connect circuit GND to the earthed chassis (say, the chassis has a point-to-point resistance of around 1 mΩ) in devices, there seem to be two rather common cases (explained below the figure)…
tobalt
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Is it better to connect ESD (TVS) Diodes to chassis ground or signal ground?

Application: We have a PCBA inside a vehicle's embedded system. The PCBA receives DC voltages from a power input connector. We do have access to signal ground aka 5V_return at the power connector and we have a mounting hole nearby that will be…
RuggedEngie
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2 answers

Connection between Chassis GND and Circuit GND for ESD/transients

All of the images in this post are from Henry Ott's Book, Electromagnetic Compatibility 2009, and I would like some clarification on some things about them. Figure 14-14 seem to be in conflict with Figure 3-24 and 15-15. The circuit GND is…
DKNguyen
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RS 485 ground signal and chassis

I have a shielded twisted pair running from one device polling several devices in an RS 485 loop. The conditions: The devices are in parallel as they should be. The termination resistors are in place as they should be. The communications are…
Raman Chopra
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2 answers

Chassis + Ground Safety

Why is it safer for ground to be connected to the chassis for an electronic system? For example, the ground on the mains supply of an AC motor in a box fan is connected to the outer chassis of the fan? My only explanation would be that in the event…
NickHalden
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When to choose Class I vs Class II AC to DC power supply?

Feels like I'm missing something obvious here, but when is it appropriate to use a Class I vs a Class II AC to DC power supply for a commercial electronic device? Should Class II only be used when the device itself is double-insulated? Should any…
Matt S
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ESD Protection on Un-grounded Chasis

I am designing a product solution which needs a 240V AC to 12V DC. I am getting that done with one of those standard laptop chargers from a reliable OEM(with necessary certifications) which looks like this with a plastic case. The DC connector from…
dev_000
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Grounding the chassis with capacitor

My question involves chassis grounding to earth ground. My PCB circuit is a simple signal generator using a microcontroller. It has a separate 'ground' from earth ground, supplied by a floating 5VDC source. (I guess we would call this a digital…
mineralwasser
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Old Variac -- chassis ground? is it safe?

I've got an old (vintage!) GenRad Variac (below) that has two prong plug and two prong socket. I want to modify it to add a safety earth pin to both input and output. In doing so, I opened it up and have realized the circuit runs through the metal…
BZo
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How is Chassis ground connection implemented for an input cable with TVS diode protection?

I believe my question is different enough in specifics to Is it better to connect ESD (TVS) Diodes to chassis ground or signal ground? to warrant a new question. According to Electromagnetic Compatibility by Henry Ott, it is advised to shunt…
Kyle Hunter
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Right way to couple DGND to Chassis ground

So we all know certain things: DGND (and subsequently AGND) needs to be coupled to Chassis ground, or Earth at one position, at least, in a device. The Earth is otherwise considered as a hazardous source of stray current and noise - and needs…
Raman
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