I'm trying to build what is essentially an RC car with a crane arm on top. The wheels are going to be powered with 2x 5V DC motors, driven by an L298n motor driver, and the arm is going to be powered by 4 servo motors. There are two additional servo motors in this schematic in order to power an axle system to turn the wheels, but that isn't definitely going into the build. Finally there is an RF24 chip in there to wirelessly communicate with the controller, which I will also make. I have drawn this schematic up (sorry if it's a mess, I'm quite new to this). I was wondering if the schematic I have drawn up would be powered correctly, or if something would break? So far, I plan on using an 8x AA battery holder as the power supply, but I'm still a little lost on powering projects, so any help would be greatly appreciated. Thanks!
Welcome to the forum
Fritzing diagrams are not well regarded on the forum because they are often difficult to interpret and this is certainly the case with your diagram
Please consider drawing a schematic of your project and posting a picture of it.
One immediate are of concern is that you appear to be planning to take 5V to power the servos and motors from the Arduino. This simply will not work as the Arduino is not designed to be use as a power supply so you will need to power them from an external supply
Sorry, I'm not too sure what a fritzing diagram is, or how I would properly draw a schematic. As for the powering of the servos and motor, do I need to power the arduino, L298n, and servos in parallel, then connect the logic pins of the motor driver and servos to the arduino?
Thanks.
It looks remarkably like the one you posted even if that one did not actually come from Fritzing
As to drawing a schematic, this is the sort of thing that I had in mind
Doing it with pencil and paper is perfectly acceptable as long as the circuit is clear but there are programs that you can uses, such as EasyEDA if you want to do it more formally
As to powering the project, what you describe is basically correct. What you are aiming to do is to have the Arduino only read and write logic signals with its pins and for the main current needed by devices such as the servos and motors to come from an external source. A common GND connection is needed for all devices so that there is a reference to measure the logic signals against
A fritzing diagram is that picture you posted. A schematic is a something you either draw in pencil or online using free software such as Kicad or Easyeda.
Arduinos provide logic not power. Logic is communicated using low voltage and very low current from the pins which you can use to control higher voltages and currents with things such as drivers, mosfets, transistors etc.
At the stage you appear to be at I would not be looking at the whole project. Have a general plan of it but start with drawing a schematic for one motor. Look in detail at your motors requirements such as current and voltage and then see what power supply would meet it. You then need to find something that will switch your power supply like a motor driver etc and it should accept logic level signals.
Code this one component and work with it on a breadboard but be aware that most motors will use more current than a breadboard should handle so this part will need hard wired or just replace the motor with an LED to test the logic.
Remember that complex things are just lots of simple things put together
Thanks for your reply,
I have done some early testing of these systems, including controlling the L298n motor drivers motors using a joystick, controlling servos with a potentiometer, and communicating between 2 arduinos using the RF24 library/chip.
The issue I'm stuck with is that most of these projects are built around your arduino being plugged into the PC, or having other very basic power supplies. I'm having trouble figuring out how to power projects with many different components with different power supplies. Most things online speak of using multiple power supplies, but having multiple battery compartments doesn't seem conducive to a clean final project. The only way I have thought of is connecting the positive and ground wire from the power supply in the positive and ground strip in the bread board, then connect each device to the same strip in the bread board through voltage regulators.
This however leaves me with more questions, like would I need a voltage regulator for every servo, or would I be able to use the same regulator for all of them since they all require the same amount of voltage? Also, does linking everything like that in parallel increase the voltage required? Like is 12V enough to power 4-6 servos, an arduino, and an L298n powering two 5V DC motors in parallel? I'm not sure how to figure out how much voltage the whole circuit needs.
Sorry for the long reply, but I have so many questions when it comes to all this. Thank you for any help you can give. 
Is there some sort of tutorial on drawing schematics like that one that you would recommend? I'm not sure what a lot of that stuff means, so I wouldn't know how to make a schematic of my circuit in the correct format.
Thanks.
Don't worry about making the schematic too formal.
What is needed is basically a block for each component with its pins numbered and/or named and for the devices to be connected by lines representing the wired connections.
It is normal for GND to be at the bottom of the schematic with positive supply voltages at the top. If there is a flow of data through the schematic such as there would be in a radio control system then it is normal for the input to be on the left of the schematic and for the data to move from left to right through the schematic
If things get too messy, such as the power supply lines to each component you can use labels as in the example I posted
rather than crisscrossing the schematic with the connections. This is particularly helpful in the case of power connections as it is usually the data connections that are of more interest
Remember complex things are just lots of simple things
Start with one thing, then add another thing. This applies to schematics as well as real components. Get a multimeter, they are cheap and you can easily tell what happens to your volts when you wire in parallel and in series.
Always check the thing you are working with to see what it’s requirements are. You need to use wire that meets the requirements to join things and you need to use other things that match or exceed the requirements of things they are connected to
This might help.
Hey,
So I tried to follow your advice, and drew up this schematic. Is it considered good enough?
I had an issue with figuring out how to show where the power supply lines were going with labels, but I think it's probably clearer than the last one.
One thing I noticed is that I now have 6 servos, the arduino, and the L298n running in parallel to 12v power, would this supply 12v to all the components, frying most of them, or split it 8 ways and supply 1.5v to all of them, powering none? The concept of powering multiple things is stumping me.
Thank you so much for your help.
The schematic is moving in the right direction.
You need to identify what supply voltage each of your components need. I would guess that the servos would need something like 5 or 6v; the drive motors 12V which could come straight from a battery; the Arduino can be supplied with 12V via its Vin pin, or 5V to the +5v pin, BUT NOT BOTH. The RF24 needs 3v3 which can come from the Arduino, etc.
The servos will need much more current than the Arduino can supply. I'm not sure why there is both +5 and +12 on the motor controller? But the +5 can probably come from the servo supply. So you need a regulator to step down +12 to +5 which can handle the likely maximum current. For something supplied by a battery this should be reasonably efficient so you should look for a switch-mode supply.
It looks like you should read up on basic electronics to understand the difference between series connection and parallel connection. Basically you connect all the units needing the same voltage in PARALLEL, each then takes whatever current it needs from the supply. You should connect all the "grounds", a/k/a 0v, together.
Thanks for your reply,
As far as supply voltage for each of the components,
I plan on using SG90s, which operate on 4.8v apparently, so I'm assuming 5v would be fine.
Then the reason that the L298n motor driver uses both 12v and 5v is I believe, because the 12v power drives the motors, whilst the 5v power drives the logic, and I've heard that powering the logic of the L298n is possible with the 5v output of the arduino, although I've heard that the L298n is inefficient and old, and a MOSFET driver is better, which is something I'm looking into. The L298n in this setup is running 2x 5v DC motors, I'm not sure if that means that the logic and the motor driving can all be powered off of 5v (supplied by an external power source, and not the arduino) or if the motors will still require the 12v, and then the logic will have to be powered in conjunction with the 5v servos using a regulator. Do you have any recommended documentation or videos on voltage regulators, or is it worth just independently researching them, as I don't have any experience with them.
Thanks for your help
Just an example, loads of different types around.
Thanks,
If I'm wiring 6 servos, an arduino, and an L298n thats powering 2 5v DC motors, am I able to just use a 5V power supply and wire all the components in parallel, therefor not needing a buck converter?
The buck converter IS the 5V PSU!! I'm assuming you want everything supplied from the same 12v battery?
Yeah I would like everything powered by the same power supply, but I'm wondering if it's necessary to use a 12v power supply when nothing in the circuit draws more than 5v?
Indeed! But if this is a vehicle, what battery would you use? A 6v battery wouldn't give enough headroom to regulate down to 5v, the next common voltage up (unless you use LiPo) is 12v.
I've been considering using LiPo, as i believe the amperage is much better for the intended purpose, so I'll keep my eye out for some LiPo batteries I guess.
Thanks heaps for your help
You could use two 3.7V lithium 18650s in series to power 7.2V motors (like a Raboesch 109-41) using a WEMOS D1 ESP32 (this also enables WiFi or Bluetooth functions and some processing speed) and it accepts up to 12V. Servos are also available at 7.2V (T-Pro SG50). It is easier to match all the voltages upfront especially when powered by batteries (you could go solar on it for charging?). To me 7.2V for the main supply seems attractive. Regardless of which supply you use mind possible peaks or lows on it when powering a motor and servo`s, you might want to add some capacitors and zener diode when powering logic directly (should you decide to use one 5V supply for instance, but 4x1.2V AAs probably lack the power you need and might be difficult to charge, the 18650s come with an array of charging modules). The suggested regulators might not be able to handle power peaks on the motors but it depends, I would avoid those as it brings losses anyway. Another option is a supercapacitor charged by a solar-panel if you do not need it to operate continuously or in the dark. Options, options...
Will you have it pick up trash or is it going to be a weed buster?