FPV Wiring Question

RENOV8R

RENOV8R

Well-Known Member
I'm installing an FPV system on a new build and have a question relating to grounding. VTX is a TBS Unify (5V) and camera is TBS59 (12v) and both are connected to a TBS Core for power which leaves only the video signal wire. Video is running through an iOSD (powered by Naza PMU). The iOSD has video and ground inputs and outputs, so my question is as all 3 components are already grounded, can I just run the video signal wire in and out of the OSD?
 
Gyro Doctor

Gyro Doctor

Electronics Tech for over 45 years
... Without knowing much about the specifics of that setup, I'd still offer the advice that the more grounding of anything that has provisions to be
grounded the better ... The 3 components (Cam, VTX, Core) being grounded doesn't mean you shouldn't also ground the OSD, otherwise you're
possibly just asking for interference ;)
 
Wildwelder

Wildwelder

Well-Known Member
The only osd I run is a tarot on my 650. It comes with the plugs and theres a ground(that I use). The fatshark vtx's I run have the power plug, which has a ground, but I just run the video wire without the ground in the second (video,5v,ground) plug and it seems fine. Gyro doctor makes a good point tho...if in doubt, whip err.... ground it out!
 
RENOV8R

RENOV8R

Well-Known Member
Thanks for the replies. That's what I've done, just ran the signal wire in and out of the OSD and everything works just fine.
 
P

Pawlik

Member
I'm a little curious what we are supposed to think a ground wire does on a device that, y'know, has no contact with the ground...
 
Wildwelder

Wildwelder

Well-Known Member
It just completes the circuit. The term "grounded" doesnt necessarily mean contact with the earth. A current travels in a complete circuit and with out the ground, the positive charge wont travel. If you pit a piece of steel on a bench off the ground and attach a pos battery canle nothing will jappen. But once you attach the ground the piece of steel will warm up or melt if you have enough charge. And this happens independant of contact with the literal "ground".
 
Gyro Doctor

Gyro Doctor

Electronics Tech for over 45 years
"Ground" is just a loose reference to negative connections (wires, terminals, etc) just like "Hot" is a loose reference
to positive connections.

With respect to electronics you might actually have several different "grounds" (floating, chassis, earth, etc) or several
"hots" (regulated or unregulated, 3.3v, 5v, 12v, battery, mains, etc).

For quads ground just generally refers to the negative side of the battery.
Like Wildwelder said, without any ground the hot doesn't have a path to complete a circuit, so no electricity will flow.
 
P

Pawlik

Member
OK that's why I asked, the terminology being used here isn't correct for standard electrical wiring. The ground and the neutral (-) are not the same thing. You have three wires in typical electrical: the hot, neutral, and ground. The hot and neutral complete the circuit, a ground is literally intended to give excess electricity somewhere to go (Earth) in case of a problem. So in this case there is only a hot and a neutral, no ground.

  • Hot: The black wire is the hot wire, which provides a 120 VAC current source.

  • Neutral: The white wire is called the neutral wire. It provides the return path for the current provided by the hot wire. The neutral wire is connected to an earth ground.

  • Ground: The bare wire is called the ground wire. Like the neutral wire, the ground wire is also connected to an earth ground. However, the neutral and ground wires serve two distinct purposes.

    The neutral wire forms a part of the live circuit along with the hot wire. In contrast, the ground wire is connected to any metal parts in an appliance such as a microwave oven or coffee pot. This is a safety feature, in case the hot or neutral wires somehow come in contact with metal parts.
http://www.dummies.com/programming/...-in-electronics-hot-neutral-and-ground-wires/
 
P

Pawlik

Member
You can still Earth ground with DC. In low voltage situations ground isn't necessary, and in a flying copter it isn't possible. Want to have some fun? Go to an electrical forum and read people trying to point out that even in those circles, and in the context of AC, the word ground is commonly misused. If you love semantics, and "common usage vs technical usage" discussions, you'll have a ball :)
 
GJH105775

GJH105775

Off and on
Moderator
Pawlik said:
OK that's why I asked, the terminology being used here isn't correct for standard electrical wiring. The ground and the neutral (-) are not the same thing. You have three wires in typical electrical: the hot, neutral, and ground. The hot and neutral complete the circuit, a ground is literally intended to give excess electricity somewhere to go (Earth) in case of a problem. So in this case there is only a hot and a neutral, no ground.

  • Hot: The black wire is the hot wire, which provides a 120 VAC current source.

  • Neutral: The white wire is called the neutral wire. It provides the return path for the current provided by the hot wire. The neutral wire is connected to an earth ground.

  • Ground: The bare wire is called the ground wire. Like the neutral wire, the ground wire is also connected to an earth ground. However, the neutral and ground wires serve two distinct purposes.

    The neutral wire forms a part of the live circuit along with the hot wire. In contrast, the ground wire is connected to any metal parts in an appliance such as a microwave oven or coffee pot. This is a safety feature, in case the hot or neutral wires somehow come in contact with metal parts.
http://www.dummies.com/programming/...-in-electronics-hot-neutral-and-ground-wires/
Click to expand...

Generally when we are referring to ground on a DC circuit the neutral is tied to the ground at some point.

Under nominal operating conditions the Neutral will be carrying current on a DC or even AC circuit, and the ground will not. Ground is usually just there for safety reasons, and less than nominal operations. However due to errors in translations, or the designer wishing to have a nominal path and a less than nominal path that is neutral the designer may choose to have a 'ground'.

On this forum and most places without crusty old EEs around we use them interchangeably to get a point across. I personally try to keep them separate after being corrected on it a few times, but am just as guilty as slipping up on it as anyone else.
 
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