A question for the experts As I am learning I do need some help checking things.
I am terrible at schematics but doing youtube on it but I hope you can follow.
I have an RC car with 6S lipo, putting out >120A
This lipo is connect to the electronic speedcontroller (both positive and negative)
This speedcontroller puts out power to the motor AND to the RX receiver (6 or 7 volt)
I have 2 ATmega chips onboard and a bunch of sensor that need an external supply because of the current demand that the ATmega cannot supply
So, I have a second lipo. 3S 500Mah something, pretty lightweight and more than enough to keep the arduino's in the air during the run time of the car.
Here it comes;
The arduino's are powered by 2 Buck (or DC-DC converters) from the 3S lipo. 1 buck for 2 Arduino's and 1 buck for all the sensors, lights etc etc.
1 of the Arduino's is reading from the RX receiver (powered by controller).
I know that I need a common ground for all items connected to the arduino, so both Buck, 3S, Sensors, lights, both arduinos need the same ground.
BUT, do I need a common ground with the RX receiver and thus, with the 6S as well? I do think so but how can I protect the whole Arduino setup from, i dont know, cross fire from the 6S. That thing is putting out major AMPS.
Any advise?
(sorry for not being able yet to draw a schematic.... will work on that skill soon!)
Your work description leaves too many possibilities and assumptions that could be made.
While you are learning about schematics I suggest you draw a simple block diagram.
I would try using simple blocks using power, ground, signals in and signals out. For my own diagrams I try to use the diagram position to reflect the way I should be connecting them (i.e. battery next to controller.
I also make heavy wires thicker on the diagram.
YES every ground should be connected. I would suggest you get one of the free or for donation cad programs such as KiCad. This is a full blown schematic capture program. Using the libraries the symbols will be correct and understood by most. This will take a few days to where you can enter schematics. Enter this design first, then enter it again under a new design, you will be surprised how much faster it will be the second time.This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
I hope this helps;
First they are called circuits because the electrons need a complete circuit back to where they came from. They get home sick and like to return to their home as soon as they can. Their home being, of course, their own power supply. They are anti social and get mad if they can't get to their own power supply, this is what happens if you try to stop them Extreme Electronics
With that in mind, trace every possible route from a power supply, through whatever wires and components that are fed from it and ask yourself how the electrons get home. If they leave the bit of circuit powered by their power supply they need a way back, that's why you join the grounds.
How can I protect the whole Arduino setup from, I don't know, cross fire from the 6S. That thing is putting out major AMPS.
That's a good question. The answer relies on being careful about how you join the grounds. Consider how much current will flow in each ground circuit and arrange them to be joined, but at the same time keeping the high currents in the thick cables and the low currents elsewhere. One way to achieve this is to have a single point where all the grounds join together. This is a single connector with wires going off to the different sub-circuits' grounds. The grounds are joined at one point and the only current flowing between them is the current that needs to flow between them.
Oh, and at the risk of being annoying, you are looking for 'advice' not 'advise'
PerryBebbington:
Oh, and at the risk of being annoying, you are looking for 'advice' not 'advise'
Oh well, it takes more than that to upset me..
I will create a schedule when I get to know KiCad a bit better but as a rule of thumb, should I place the common ground as close to the 6S with thick wires and the rest with thinner wires and thus a bit further away?
That way the higher current has the least resistance to get back to their own beds.
Should I place the common ground as close to the 6S with thick wires and the rest with thinner wires and thus a bit further away?
I don't really know how to answer that. The common ground does not have to be carrying the high current, it just has to have a connection to the cables that are.
It will be spring before I actually going to solder and build it I think so I have some time to investigate. I am also learning to code as efficient as possible (a month ago I didnt even knew Arduino existed so to speak). At this point I have all the parts working, now learning to code with functions etc. Short; I have a bit of time.
2nd challenge is that all of this need to be as small/tiny as possible with the right cooling if needed.
Question regarding your diagram; the three yellow wires from Arduino 2 to the Rx, what are these signals? Are they wires or radio?
If you don't think you need to make a printed circuit board I would suggest you look at TinyCad. It is a schematic only program and for me it is more intuitive than Kicad. It is also free.
JohnRob:
Question regarding your diagram; the three yellow wires from Arduino 2 to the Rx, what are these signals? Are they wires or radio?
If you don't think you need to make a printed circuit board I would suggest you look at TinyCad. It is a schematic only program and for me it is more intuitive than Kicad. It is also free.
John
Those 3 are really wires to read out the channels from the receiver. In reality there are 6 but not important here.
For final product I will be ordering PCB. So I might learn it as well. thx
As I am learning I do need some help checking things.
