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I have a few diagrams which shows where the ground comes from.
So which is the correct one? DOSD Wiring Vtx and Cam to DOSD DOSD Wiring Lipo to DOSD DOSD Wiring Cam to DOSD DOSD Wiring Vtx to DOSD |
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To find my house, go north 1 mile, turn left, then your second right, my house is on the left. So, can you find where I live with that? No. Why? Because we have no common reference with each other. Now let's do this with a common reference. From the corner of 1st and A street, go north 1 mile, turn left, then your second right, my house is on the left. The chance of you understanding and finding me is significantly improved...unless you're my wife, she can't find her way out of a parking lot...that's a different story though... Electronics don't communicate verbally, but via changing voltage levels. If they don't understand each other's voltage level they might not 'understand' the signal being sent. Now, where do we make this common ground point? That kinda really doesn't matter. Most electronics circuit boards use a common ground plane, i.e. all the ground connections essentially connect to each other. As long as the negative lead on your two batteries connect to this ground plane they now have a common reference and will understand each other's signals. Each piece of electronics must connect to this ground plane to operate properly. If a gnd from one piece of electronics connect to both the direct ground as well as another piece of equipment that then connects to the direct ground then you have a ground loop, i.e. the current can pass both directly to the ground plane as well as thru the second piece of equipment and then to the ground plane. This is where issues can occur. Now, if each separate piece of equipment connected to the exact same spot then no ground loops are created as the current through each component can ONLY flow to a common point, not through anything else. Does any of that help? Yeah, it can be confusing and I am an electronic repair tech and still get confused. Here's a quickly little article you can look at too: http://fpv-japan.com/technical-info/...issue/lang/en/ . |
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Sorry if what I just said made no sense |
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Last thing...The reason I said connect only the Signal wire from the ESC is because I'd recommend using a Switch Mode External BEC to power your electronics (Rx, servos) with. If you're going to use the speed control's internal BEC then you want to connect ONLY the + and Signal leads and leave the negative lead not connected. |
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Thanks Fantastic... I know the misspelled name....
So its figure 2. Yes I do have a CC 10AMP BEC to power the Rx and Servos. Quote:
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Okay, another example. Sorry, I love examples. The main highway through your town is designed to flow lots of cars at high speed without problem (wider roads, no stop signs, etc). Since this is the ONLY place the traffic can flow no problems occur. Now take that same highway traffic and funnel it onto a one lane side street, through a school zone, with lots of dips and pot holes in the way. The traffic flow is going to jam up and people get pissed, and tempers get hot, and you have a road rage melt down...not good and no one is happy, Now some architect flunky designed the highway so three lanes of traffic can go down the highway, but one lane of that highway traffic HAS TO take that one-lane side street with all the same obstacles and then connects it back to the major highway five miles down the road...(the 'ground loop). While most of the traffic 'flows' down the major highway just fine, some of that traffic gets bundled up, bottle necked, heated up, yet has no choice to go anywhere else because of all the cars behind it just pushing it along...like it or not. The one lane traffic overheats, breaks down, etc. |
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With all that said, that's not how I have my system connected. I have my camera, VTx, and DOSD video GND pin connected to each other. My video flight pack + and - wires connect to the DOSD power input pins. My video equipment + lead connect into the video battery + line. I don't recall if my video equipment GND pins also connect to the video battery ground or not...I'd have to double check. If so, then, Yes, I have a ground loop. It's a low current ground loop and not so critical and hasn't caused me any issues. The one thing I did make sure to do was only connect the Signal wire from my ESC servo leads to the DOSD. |
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"I have my camera, VTx, and DOSD video GND pin connected to each other."
You mean like this? or care amend this diagram? Cheers. Quote:
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Thanks a lot for your response,
My settings are as follows, AP Rotgain 68.00 Rot limit 30.00 Rot step gain 6.00 Max heading chg 45 deg AP Rocgain 50.00 Roc limit 10.00 Roc stepgain 6.00 Max alt chg. 10.00m Low speed limit 20.60 kph Cruise speed 32.00 kph Cruise alt. 150m Decsent mode 1 Throttle step 2 Auto stabilization gain 0.000 Gps stabilization gain 0.000 Altitude limit 30.000 Hit distance 200m Current waypoint 0 Waypoint mode visit The only thing i have connected to the osd in addition to gps, current sensor and rssi is ppm channel 9 which is going to channel 9 of the Dlink. I have nothing connected to the pwm outputs. So if your refering to controlling any channels with the osd I don't think I am. Could that be the problem. I do have Ailerons, elevator, rudder and throttle connected to rx and i am powering the osd with the current monitor and and rx thru the speed controllers bec. I assume the ppm is sending the 5 volts to the osd. I'm also powering video with seperate 12 v battery. Is this enough info? Thanks, Dennis |
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That drawing looks vaguely familiar.
#1 one has a loop shown with green arrows. The key thing to keep in mind, is that each component should have only one ground wire to it. The exception is the DOSD board. It has a main ground next to the main power pin and it also has a servo rail ground, which feeds only the PWM's and PPM. In figure #1, the Vtx and camera each have two, forming a loop. And before anyone says it....yes, my original drawing shows two grounds to the camera. It's a Sony board cam and the ground had to be connected to the GND pin next to the video pin on the OSD in order for it to work. Please don't ask why, it just did. ETA: I've never had high current draw through any component (other than a motor or ESC) unless it was shorted...in which case it matters not how you have it wired. |
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'main' PWM-to-FY20 connection as the current from the connected servos would all flow thru that one wire. I think the big concern on ground loops is getting high current flowing through a circuit that isn't designed for high current. On the lower current items, a ground loop would be more likely to just induce 'noise' into the system vs burning something out. The noise can be an irritant, the burnt components can be a drain on your bank account when you have to buy replacement equipment. |
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