(solved) electric isolation .

i have a 2A 5V power supply , i wan't it to supply power for some servos an arduino and a 3.3v module , it's just for testing , later on i am going to replace the power supply with a battery but for now this is what i have .
now the problems are .

when i place the atmega328 with the servos , and when the load on the servos get's high the atmega328 stops working normally and i am aware that that's not good for the chip .
so i isolated it with a 5v regulator , but it still does not work that well , i also have a 3.3v regulator in the circuit . everything works fine but once i put load on the servos it all becomes a mess .

"Some servos" sounds like more than 2, so let's say 3 servos.... they can draw 1A each easily, so "when the load on the servos get's high" you may easily be overloading your 2A supply and then the voltage drops.

JimboZA:
"Some servos" sounds like more than 2, so let's say 3 servos.... they can draw 1A each easily, so "when the load on the servos get's high" you may easily be overloading your 2A supply and then the voltage drops.

i can't provide more than 2A . so i must either somehow limit the servos or find an other solution ... what do you think ?

Are the servos running off the 5V /2A supply ?

raschemmel:
Are the servos running off the 5V /2A supply ?

yes directly , if that has to be changed i'd change it .

amine2:
i can't provide more than 2A

raschemmel:
Are the servos running off the 5V /2A supply ?

amine2:
yes directly , if that has to be changed i'd change it .

That's a bit contradictory....

As you should know now, it would be helpful If you told us which servos, which module, and if you draw a schematic of how you've wired them .

This isn't rocket science. Get a DMM and measure the current drawn by the 2A supply with all the servos running at full load.

raschemmel:
This isn't rocket science. Get a DMM and measure the current drawn by the 2A supply with all the servos running at full load.

at the end though i am planning to use the 5v current coming from the Lipo battery 5v socket . i think that might actually handle more than 2A (i think) .
though some RC planes only use the 5v rail incoming from the battery and the planes contain Servos and chips though they somehow manage to distribute current in a correct way , i can't understand how though

at the end though i am planning to use the 5v current coming from the Lipo battery 5v socket . i think that might actually handle more than 2A (i think) .
though some RC planes only use the 5v rail incoming from the battery and the planes contain Servos and chips though they somehow manage to distribute current in a correct way , i can't understand how though

So now you're making a GUIDED MISSILE ?

The 5V regulator in RC planes is actually the BEC (Battery Eliminator Circuit), so named because early RC planes had to have a second battery for the electronics because the semiconductor industry wasn't that advanced (I think that's the reason) The BEC is just a voltage regulator (rated for about 1.5A but mine are 3A). The premise is that when you fly your airplane too fast or burnup your motor , it might damage your ESC which has it's own BEC. If you're too lazy to add a standalone BEC, when you fry your ESC, you lose servo power and crash. With a standalone BEC, you fry you ESC, (you see the smoke contrail coming out behind your aircraft) and you can still do an emergency landing because you still have servo control.

raschemmel:
So now you're making a GUIDED MISSILE ?

The 5V regulator in RC planes is actually the BEC (Battery Eliminator Circuit), so named because early RC planes had to have a second battery for the electronics because the semiconductor industry wasn't that advanced (I think that's the reason) The BEC is just a voltage regulator (rated for about 1.5A but mine are 3A). The premise is that when you fly your airplane too fast or burnup your motor , it might damage your ESC which has it's own BEC. If you're too lazy to add a standalone BEC, when you fry your ESC, you lose servo power and crash. With a standalone BEC, you fry you ESC, (you see the smoke contrail coming out behind your aircraft) and you can still do an emergency landing because you still have servo control.

making a guided missile is not very hard if you have money , tools and a decent knowledge of physics (even though gyroscopes are fast enough to do that for you these days ) i am just completing my RC plane .
so should i connect the atmega328 and the servos directly to the 5v rail ? obviously that would not work .
+i also have a 3.3v device (the NRF receiver) that's why i am using a 3.3V regulator .

The arduino and servos should be powered by a standalone BEC . The arduino 5V pin should be connected to the BEC 5V output, as should the servos. What you need to know is that your receiver should be powered by the standalone BEC , NOT by the 5V coming from the red wirevon the 3-,conductor ribbon cable coming from the ESC which is plugged into the receiver. In order for this to work, you need to do two things :

1- "CUT THE RED WIRE !" ( of the 3- wire ribbon cable with the black servo connector that comes from the ESC ) This prevents the ESC 5V from reaching the receiver.

2- Plug a similar servo cable into an unused channel of the receiver with the black ( or brown) wire of the servo cable connected to GND o 5V/2A supply and the red wire of the cable plugged into the unused channel connected to the +5V of the 5V/2,A supply. This powers the receiver from the 5V /2A supply . I don't agree with your plan to use a Lipo because a 1S Lipo is 4.2V ,( charged) and a 2S is 8.4 V ( charged), so a single cell is too low and a 2 cell is too high.

raschemmel:
The arduino and servos should be powered by a standalone BEC . The arduino 5V pin should be connected to the BEC 5V output, as should the servos. What you need to know is that your receiver should be powered by the standalone BEC , NOT by the 5V coming from the red wirevon the 3-,conductor ribbon cable coming from the ESC which is plugged into the receiver. In order for this to work, you need to do two things :

1- "CUT THE RED WIRE !" ( of the 3- wire ribbon cable with the black servo connector that comes from the ESC ) This prevents the ESC 5V from reaching the receiver.

2- Plug a similar servo cable into an unused channel of the receiver with the black ( or brown) wire of the servo cable connected to GND o 5V/2A supply and the red wire of the cable plugged into the unused channel connected to the +5V of the 5V/2,A supply. This powers the receiver from the 5V /2A supply . I don't agree with your plan to use a Lipo because a 1S Lipo is 4.2V ,( charged) and a 2S is 8.4 V ( charged), so a single cell is too low and a 2 cell is too high.

i am actually speaking about a 3S battery , and the 5v i am talking about is the BEC of the ESC .
i have a couple ESCs that i don't need , i think ill just use those as standalone BECs .
with 5v rail , i am speaking about the 5v wire coming from the ESC not the Battery wires .

i am actually speaking about a 3S battery , and the 5v i am talking about is the BEC of the ESC .
i have a couple ESCs that i don't need , i think ill just use those as standalone BECs

That's fine. But only a fool uses the same ESC that powers the motor to supply 5V to the servos , for reasons I already explained.

raschemmel:
That's fine. But only a fool uses the same ESC that powers the motor to supply 5V to the servos , for reasons I already explained.

yes i understood that , that's why i am going to use some extra ESCs just for that , i couldn't find any BECs but i have many extra ESCs that i wont use , so ill just use the BECs in those .

the issue is now , that i did try wiring the arduino and the servos all to a single BEC but that did not work , because once the load get's high , the arduino stops working .

Don't tell anyone I told you this but if you use a substantial electrolytic filter cap (Like 470uf to 1000uF),
you can tie the outputs of two different BECs together, providing they are sharing the same ground.
2*1.5V = 3A

raschemmel:
Don't tell anyone I told you this but if you use a substantial electrolytic filter cap (Like 470uf to 1000uF),
you can tie the outputs of two different BECs together, providing they are sharing the same ground.
2*1.5V = 3A

thank you , or can i just use two BECs , one for the arduino , and one for all the motors ?
i am also using ESCs for BECs , would the extra motor controller stuff waste too much energy ?

or can i just use two BECs , one for the arduino , and one for all the motors ?

That's actually a much smarter option. It is never a good idea to power a uP from a power source that is also powering motors.

Using ESC just for the BEC is not going to disipate any power in the motor driver section because there is no load connected to the motor outputs. Thus the mosfets have OPEN drains. There is nothing to dissipate any power.

raschemmel:
That's actually a much smarter option. It is never a good idea to power a uP from a power source that is also powering motors.

Using ESC just for the BEC is not going to disipate any power in the motor driver section because there is no load connected to the motor outputs. Thus the mosfets have OPEN drains. There is nothing to dissipate any power.

Thank you very much Raschemmel , you solved my problem . i owe you one .

You still owe us a current measurement of all the servos running at full load .