My current system is:-
Channel 3 = throttle - to Esc BUT have removed the + and - from esc servo wire - leaving only the signal wire
Channel 6 = 'spare' channel - have connected in from ubec just the + and - to provide ubec power for rx and servos.
ALL works fine.
BUT I need the 'spare' Channel 6 for a new purpose.
Question: Is it ok to take the ubec incoming + away from Channel 6 and - and move them to 'accompany' the throttle signal wire on Channel 3 ??
Yes that`s fine, the 5v rails are common on the +ve pins and -ve pins so there is no difference
Yea thats fine :-) the + & - are a common rail all connected so you can in effect use a Y lead on any channel to feel the rx with power
Well you just beat me to it Randall with the Y lead. However it is a slightly odd way to wire.
If we assume that the ESC does not have a BEC, which is why you use a separate UBEC, you would not have to remove the +ve wire connecting to the servo. It is not supplying power to the rx.
If we assume that the ESC has a BEC but for some reason you do not with to use that, then it is sufficient to remove only the +ve wire. The -ve wire is called the common (not to be confused with common rails) and is the return path for the signal wire between ESC and rx.
You have removed both +ve & -ve between ESC & rx, therefore the ESC circuit must be completing via the battery and UBEC wiring to the rx, which is a roundabout route.
Diagram?
Quote from: electrotor on December 19, 2012, 11:24:03 PM
Well you just beat me to it Randall with the Y lead. However it is a slightly odd way to wire.
If we assume that the ESC does not have a BEC, which is why you use a separate UBEC, you would not have to remove the +ve wire connecting to the servo. It is not supplying power to the rx.
If we assume that the ESC has a BEC but for some reason you do not with to use that, then it is sufficient to remove only the +ve wire. The -ve wire is called the common (not to be confused with common rails) and is the return path for the signal wire between ESC and rx.
You have removed both +ve & -ve between ESC & rx, therefore the ESC circuit must be completing via the battery and UBEC wiring to the rx, which is a roundabout route.
Diagram?
Electrotor - you make some interesting points.
Esc does have a BEC, but after reading various Forum threads, I decided it was safer to use a separate supply.
+ and - feeds are taken from the downstream side of an ez voltage sensor to BEC and on to receiver channel. A separate feed is also taken from ez sensor to power immersion vtx and camera.
Ezosd is fed from voltage sensor.
Rightly or wrongly, I wired this way to try and avoid a 'dreaded' earth loop thingy problem.
Quote from: wgt40w on December 20, 2012, 11:23:18 AM
Quote from: electrotor on December 19, 2012, 11:24:03 PM
Well you just beat me to it Randall with the Y lead. However it is a slightly odd way to wire.
If we assume that the ESC does not have a BEC, which is why you use a separate UBEC, you would not have to remove the +ve wire connecting to the servo. It is not supplying power to the rx.
If we assume that the ESC has a BEC but for some reason you do not with to use that, then it is sufficient to remove only the +ve wire. The -ve wire is called the common (not to be confused with common rails) and is the return path for the signal wire between ESC and rx.
You have removed both +ve & -ve between ESC & rx, therefore the ESC circuit must be completing via the battery and UBEC wiring to the rx, which is a roundabout route.
Diagram?
Electrotor - you make some interesting points.
Esc does have a BEC, but after reading various Forum threads, I decided it was safer to use a separate supply.
+ and - feeds are taken from the downstream side of an ez voltage sensor to BEC and on to receiver channel. A separate feed is also taken from ez sensor to power immersion vtx and camera.
Ezosd is fed from voltage sensor.
Rightly or wrongly, I wired this way to try and avoid a 'dreaded' earth loop thingy problem.
I can see your reasoning but with a single power supply (flight battery) you are unlikely to get an earth loop problem. I normally go for the simple solution to reduce the number of wires and connectors but there's no right and wrong way, it's preference.
The earth loop with the OSD`s comes from the ESC`s -ve Bec wire. It creates a loop back from the ESC, through the OSD and back to the OSD current sensor. The reason for the separate Bec is to remove that loop but provide 5v still.
Quote from: Coyote on December 20, 2012, 12:03:06 PM
The earth loop with the OSD`s comes from the ESC`s -ve Bec wire. It creates a loop back from the ESC, through the OSD and back to the OSD current sensor. The reason for the separate Bec is to remove that loop but provide 5v still.
OK, understand where the video might be affected by an earth loop.
I didn't consider OSD because wgt40w didn't say he was using one in his setup.
Oh its not video related, the loop can enable the current that the motors using to go through the Bec -ve wire. Melts the cable, normally takes the OSD / plane with it.
I just presumed that with him wanting to power via a separate Bec like that there must be an OSD involved, might be wrong though
I wired using a separate supply also partly because the esc that came with the plane (lanyu Raptor) got a reputation (on this forum of often failing).
I repeat that my current wiring system DOES work perfectly OK - my real question was just about 'mixing' on one rx channel + and - supply from separate suppy to esc, with a signal wire going to the esc.
I thought it would be OK and your replies have confirmed it.
Thanks guys.
Quote from: Coyote on December 20, 2012, 06:57:18 PM
Oh its not video related, the loop can enable the current that the motors using to go through the Bec -ve wire. Melts the cable, normally takes the OSD / plane with it.
I just presumed that with him wanting to power via a separate Bec like that there must be an OSD involved, might be wrong though
And there was me thinking video interference, not melted plastic. Thanks for the explanation Coyote you old droid.
;)
Yeah, I've been getting the dreaded 'ground loop' problem in my video, it's fine one 1 battery with NO current sensor, but the second a use a current sensor (and use that to power the OSD) a get the problem.
If I tap the OSD off the balance lead or use a separate OSD battery, it's fine... gonna look into a separate UBEC to power the system, see what differences it makes.
Good points and info and tips y'all.
Keukpa
Ground loop explained
http://fpv-japan.com/technical-info/fpv-uav-system-power-considerations-avoiding-multiple-ground-return-paths/lang/en/ (http://fpv-japan.com/technical-info/fpv-uav-system-power-considerations-avoiding-multiple-ground-return-paths/lang/en/)
Nigel.
Devonian
Great Link to a concise explanation.
Many thanks - Karma issued.
PS I do have an OSD and all the reasons (which I had partly forgotten) are mentioned in the Link as to why I went for a separate ubec supply. All of which I gleaned from this Forum !!