My grandson has built a remote control ROV. On the transmitter side he has the following:
1--joystick----forward and back motorcontrol
6--potentiometers --1 for pan on camera--1 for tilt on camera and 4 others to control the Mearm ( to control the servos)
1--nrf24l01
All of these need 5 volt
Is he going to over load his 2560 mega board? And is doing some thing wrong by tying all the grounds and all the 5 volt wire to just one spot each on the 2560?
chickenhawk:
My grandson has built a remote control ROV. On the transmitter side he has the following:1--joystick----forward and back motorcontrol
6--potentiometers --1 for pan on camera--1 for tilt on camera and 4 others to control the Mearm ( to control the servos)
1--nrf24l01
All of these need 5 volt
Is he going to over load his 2560 mega board? And is doing some thing wrong by tying all the grounds and all the 5 volt wire to just one spot each on the 2560?
Probably already has overloaded the poor thing!
The servos need their OWN 5 volt supply because the current needed is way to much for the 2560.
The nrf2401 needs quite a bit of current at 3.3 volts when it transmits.
Time to redesign the power.
Paul
This the transmitter side, so no servos. Nrf24l01 has adapter to take it from 5 volts down to 3.3 volts
Tank side has servo driver with own power supply.
Worried about having 8 things all trying to pull 5 volts of the 2560 mega board
The look at the data sheet/specifications for the devices and add up the current they draw. Pretty simple way to answer your concern.
Paul
I think what we are looking for is a board that we can power with a 9 volt battery, that we can turn on with a jumper wire from 3.3 volt or 5 volt pin on the 2560. Then we can run all the 5 volts and grounds from it. The 2560 is mounted inside a case and is turned on with a external switch. We don't if there is something like this is out there or if this is something we will have to build.
So in the end we will have 1 --9 volt battery to run the 2560 and 1--9 volt battery to run the second board. That way we won't have to run everything off of the 2560 board. Don't know if all of this makes sense or not, but willing to listen for ideas.
chickenhawk:
My grandson has built a remote control ROV. On the transmitter side he has the following:1--joystick----forward and back motorcontrol
6--potentiometers --1 for pan on camera--1 for tilt on camera and 4 others to control the Mearm ( to control the servos)
1--nrf24l01
All of these need 5 volt
Is he going to over load his 2560 mega board? And is doing some thing wrong by tying all the grounds and all the 5 volt wire to just one spot each on the 2560?
Don't count the peas: get a 1$ step-down buck converter and feed the Arduino at 5V Vcc.
The 2560 has it's own 9 volt battery to power it, what we are looking at is to get away from having everything plugged into the 2560. He has come up with a DC jack for it's own 9 volt power to a L7805 to go from 9 volts to 5 volts then to a 1 channel dc 5v relay module (turning on when the 2560 is turned) then having all the 5 volts and grounds to pins off of the relay module. Yes?
chickenhawk:
The 2560 has it's own 9 volt battery to power it, what we are looking at is to get away from having everything plugged into the 2560.
You should not be operating a Mega 2560 from 9 V batteries - that is simply foolish! Wasting 45% of your battery power merely to heat up your enclosure makes no sense at all - unless perhaps you require de-icing. 
And you are actually wasting 63% of the power your NRF24L01 is using,
The microcontroller board operates on 5 V. Either you find a battery to provide close to 5 V (such as four NiMH) or you use a 9V battery with a switchmode "buck" converter to provide the 5 V which wastes only about 15% of the battery power. And then you can power everything from the same source.
If you have separate power sources for the potentiometers, then you will have unstable readings from the ADC.
Since I doubt the Mega 2560 is using its USB interface, that part is also wasting battery power. You would be better off to use a board that does not have the USB interface.
It is not clear what a relay module has to do with anything here. What is it supposed to do in the transmitter? A 5 V relay would waste almost as much power as the Mega 2560.
Paul__B:
You should not be operating a Mega 2560 from 9 V batteries - that is simply foolish! Wasting 45% of your battery power merely to heat up your enclosure makes no sense at all - unless perhaps you require de-icing.
The Mega is also not the very best choice for building a remote control. Forget 5V, nothing is requiring 5V. A Pro Mini 8MHz runs at 3,3V and will drive the NRF24L01 directly saving a lot of power, parts and room in the transmitter.
Feed it with a good 3,3V switching buck converter from e.g. two LiPos and you wil get a power efficient system.
I thought the OP chose a Mega 2560 with a requirement for 10 ADC inputs.
Reading more carefully, he wants only six ADC inputs and a Pro Mini would in fact be the sensible choice. And for that, three alkaline AA cells would be just fine (even for a 16 MHz version).
Paul__B:
I thought the OP chose a Mega 2560 with a requirement for 10 ADC inputs.Reading more carefully, he wants only six ADC inputs and a Pro Mini would in fact be the sensible choice. And for that, three alkaline AA cells would be just fine (even for a 16 MHz version).
The 3,3V version can drive the NRF24L01 directly and a 3,3V buck converter provides a reliable power supply to the NRF24. That simplifies the circuits.