Power wiring diagram for boscam 5.8ghz tx, 808 #16v2 with quad's power system

[Johan]

....

Only port 1 needs to be connected to a UBEC, but the remaing 7 are routed nowhere. if you try to draw off, say port 8, you will be grounded but you will get no power from the other 3 ESCs. you *could* pull out one of the ESC's power lines (from ports 2-3, NOT port 1), and connect it to the boscam power line, but that's a messy connection.

Crafty Dan, are you sure? I know that if you look at the back of the KK2, the middle (+5V) pins look isolated, but if you connect a Resitance meter between the +5 of each of these ports, you'll measure 0 Ohm, meaning the +5V of ports 2 to 8 are interconnected.

On my tri I have :
1 ESC (with 5V) on port 1, this powers the KK2 obviously and through that the transmitter
1 ESC (with 5V) on port 2,
1 ESC without 5 V on port 3

1 servo on port 4, which gets its 5V power from the common port2 - port8 5V connection ....

This is how it is in the KK2 manual:

"The M1 connector must always have a ESC connected, because this ESC will be the only one that supplies the FC with 5V power. This ensures stable power to the FC.


The M2 to M8's 5V power pin is connected together, and any servos here will be supplied by any ESC'sconnected here. There is not necessary to cut the 5V (red) lead on any ESC unless it has a SwitchingBEC."

Since my ESC's are SBECS, I folded back ont of the remaining +5 cables

 

[xuzme720]

It's ok. I think Dan was just trying to get him back on the balance tap where he should be. That seems to have worked.

But I will agree with Johan as far as motor ports 2-8 being inter-connected at both the ground and the middle pins for 5v. ESC 2 or 3 on a tri will provide power to the servo on 4, but power from an ESC to a video transmitter is going to be a little noisy. the balance tap or the battery feeds themselves are better and cleaner.

 

[Craftydan]

you're likely right -- I haven't checked, but that makes me nervous. not a problem on the current ESC (using a QBrain) but don't like chaining regulators in parallel. it's just unnatural.

 

[Johan]

you're likely right -- I haven't checked, but that makes me nervous. not a problem on the current ESC (using a QBrain) but don't like chaining regulators in parallel. it's just unnatural.

Hi Dan, that is why i thought I'd mention it before others connect all their ESC's (I read the Multistars are the switching type).
My M2 ESC powers my rear servo, so that 5V does come through to the M4 port.

Indeed I think the board itself is misleading: on the back these pins appear to be 'islands'

 

[Craftydan]

Hi Dan, that is why i thought I'd mention it before others connect all their ESC's (I read the Multistars are the switching type).
My M2 ESC powers my rear servo, so that 5V does come through to the M4 port.

Indeed I think the board itself is misleading: on the back these pins appear to be 'islands'

Yeah, but it's also a multi-layer PCB -- no telling where the internal traces are going. I get their tri-servo design decision, I just don't agree with it. The senseble thing would have been to route 3&4's power to a "tri power" jumper, else isolate them completely. Seems sensible isn't what they chose.

 

[Johan]

Yeah, but it's also a multi-layer PCB -- no telling where the internal traces are going. I get their tri-servo design decision, I just don't agree with it. The senseble thing would have been to route 3&4's power to a "tri power" jumper, else isolate them completely. Seems sensible isn't what they chose.

That would be a great idea: just an extra jumper: no worries for if you do not need to power anything extra (quads, hex's, octos's), use the jumper if you do!

 

[xuzme720]

I think the driving goal for the KK2 was, and still is, to keep it simple and cheap. Dan's isolation idea seems to be simple to us, but without a full schematic of the traces, it's hard to make that kind of judgement. I would definitely like to have a jumper for the tri setup and have to individual motor feeds separate. I'd hate to forget about it and plug in a few SBEC ESC's and then watch the magic smoke leave...
I wish I knew how they put it in the first time because I have never been able to get it back in there...

 

[Craftydan]

I think the driving goal for the KK2 was, and still is, to keep it simple and cheap. Dan's isolation idea seems to be simple to us, but without a full schematic of the traces, it's hard to make that kind of judgement. I would definitely like to have a jumper for the tri setup and have to individual motor feeds separate. I'd hate to forget about it and plug in a few SBEC ESC's and then watch the magic smoke leave...
I wish I knew how they put it in the first time because I have never been able to get it back in there...

Oh, I understand *why* they did it -- through hole components take up precious space on *every* layer, but if they can leave the voltage sensor unwired, they could have pulled this to pads on the side and had the user solder on a jumper or header. Plenty of other options -- Still don't like what they picked for this one.