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Thanks Teralift. I've attached a wiring diagram with my proposed setup. My concern is creating a ground loop with the UBEC/servo/FC grounds. Does this look right?
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Last edited by goog; Apr 23, 2017 at 01:04 AM.
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Awesome ! exactly what fpv plane user (I) needs ! thanks again
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Thanks terralift. Will be doing this on y newest build. I had heard however that reversing a diode will allow one to run both sources together. Does anyone know anything about this? Is that the diode you are recording we remove?
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Thread OP
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Quote:
At the same time, you will loose an option to power the whole board from the ESC-mid rail. To summarize Normal: ESC-mid rail can power the main 5V rail if applied voltage is higher than that of other sources. Other sources does not power the ESC-mid rail. Removed: ESC-mid rail is isolated from other sources. Reverse: Other sources will power the ESC-mid rail, as well as rest of the 5V rail. |
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Thread OP
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Quote:
In that case, if the voltage on the ESC-5V rail is higher than other sources, then it will power the entire FC. Otherwise, the diode will prevent reverse voltage/current. These two cases may alternate as voltage on ESC-5V goes up and down when servo moves. If you are going to power servos, I strongly recommend you isolate the ESC_5V, as back rush from servo propagating to main 5V rail is the worst scenario. |
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What is back rush from servos? Is it where a servo causes voltage spikes that will go through the diode and fry the fc? In that case, won't the other servos and the rx absorb the spikes?
I have a relatively small fixed wing with two 9g servos for ailerons, two 4g for the tail, two 9g for pan and tilt and an rx of course connected to the Omnibus F4 pro v2 (clone). I thought the onboard bec was rated at 3A so do I really need to remove the diode and change esc to one with bec? I think I read the diode is rated at 1A. In what way can that be a critical factor? |
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Thread OP
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@RCnator
Servos are inductive load and therefore noisy in nature, if not harmful to other components that shares the same power rail. I have seen a medium 5V servo generating as high as 13V spike on the power rail, and it is a common practice to isolate digital circuit from inductive load. If you have a working system, that's fine. |
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Last edited by teralift; Jan 03, 2018 at 06:09 AM.
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I have not tested it yet but already soldered on an ESC without bec. I could change it though but the other ESC is quite a bit heavier and bulkier. Still, I want a reliable system and not fry anything. I have two other bigger fixed wings though that I use bigger ESCs on from the beginning with inbuilt bec where I will be sure to remive the diode.
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Hello
first I want to apologize in advance for being electrictally challenged, I used wiki to find out that a diode can be viewed as an electronic version of a check valve.... I have this board FLIP 32 - F4 - OMNIBUS V3 PRO and am planning to run INAV in a Mini Talon with four servos it appears to be possible to perform this "diode mod" then just physically plug my ESC and four servos into this row of pins on the FC, just like I do in my sport planes into an Rx thus avoiding building some sort of external servo rail for + & - all other board functions ( vtx, beeper, sbus, osd, etc ) would remain functional am I understanding this correctly ??? if so, what do I need to physically "do" to this diode ??? thx FB |
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@teralift, 13V sure is a hell of a lot. I actually went ahead and did the mod and exchanged the ESC to one with BEC, partly also because I was told it is better, without further explanation, to use airplane ESCs in airplanes.
@Flying Beagle, I believe you do. I can see you have been a member here since 2004, so just take your soldering iron and desolder the diode. |
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....you can be in this hobby a lifetime,
design, build and fly dozens of airplanes, and never pick up a solder iron |
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