Hello everybody,
i am beginner in circuit designing. i started learning about circuit designing with protection parameters that's have to take care of.
i want to use 12 Volts 7.2 Amp battery for running 12 Volts DC Motor using TIP120 transistor as well as Arduino Uno. How Much current is required to operate arduino uno and how to do it. I found DC Motor have specification of 12 Volts 0.8 Amp. I want to three DC Motors.
Recommend some tip and tricks to do it. 
I think it's safe to run Arduino with 12 V. So it could use the same battery as your motors.
If you plan to use an Arduino board, like in your picture, you can wire the 12V from the power supply to the Vin pin on the Uno. That way, you use the voltage regulator on the Uno board, which also has the appropriate capacitors on it.
(By the way, I believe your flyback diodes are the wrong way round.)
No such thing as a 12V 7.2A battery.
Show us the battery label, datasheet, specs.
INTP:
No such thing as a 12V 7.2A battery.
Show us the battery label, datasheet, specs.
Link: 12V 7.2Ah Sealed Lead Acid Battery with F1 Terminals - TLV1272F1
Jobi-Wan:
If you plan to use an Arduino board, like in your picture, you can wire the 12V from the power supply to the Vin pin on the Uno. That way, you use the voltage regulator on the Uno board, which also has the appropriate capacitors on it.(By the way, I believe your flyback diodes are the wrong way round.)
Sir, I am a beginner in electronics. Can you please tell me, How to correct it. I am planning to supply power using 7805 to Vin of the board. Is it okay to do it.
suyog44:
Link: 12V 7.2Ah Sealed Lead Acid Battery with F1 Terminals - TLV1272F1
Thank you for the link. That is a 7.2Ah battery. That is not the same as a 7.2A battery.
Your concerns about your total current draw are unnecessary- that battery can handle up to 108A of current, which you are not going to reach even if you had hundreds of Arduinos.
Now how about a datasheet/specs for your motors? What do you want to do with them- just turn them on and off in a single direction, back and forth, variable speed, did they come with any driver boards?
suyog44:
I am planning to supply power using 7805 to Vin of the board. Is it okay to do it.
(Disclaimer: I am also a beginner.)
If you use your own 7805, you should wire the output to the 5V pin on the Uno. (You will likely need to put some capacitance at the input and output. Datasheet will tell you.)
But you can also wire the 12V from your power supply to the Vin pin on the Uno.
The Uno has its own voltage regulator (plus capacitors) on board. The Vin pin is connected to the input. The 5V pin is connected to the output.
The diodes should be oriented so that they don't conduct under normal circumstances, when the motor is running. Because of the inductance in the coils of your motor and the momentum of the motor itself, current keeps flowing for a bit when you switch off the motor. The diodes are to provide a return path for that current.
INTP:
Now how about a datasheet/specs for your motors? What do you want to do with them- just turn them on and off in a single direction, back and forth, variable speed, did they come with any driver boards?
Here is the link for motor that i want to use https://www.alibaba.com/product-detail/TT-555-122250-Micro-dc-gear_60198926025.html
Jobi-Wan:
But you can also wire the 12V from your power supply to the Vin pin on the Uno.The Uno has its own voltage regulator (plus capacitors) on board. The Vin pin is connected to the input. The 5V pin is connected to the output.
The diodes should be oriented so that they don't conduct under normal circumstances, when the motor is running. Because of the inductance in the coils of your motor and the momentum of the motor itself, current keeps flowing for a bit when you switch off the motor. The diodes are to provide a return path for that current.
Actually I am replacing Arruino Uno with Arduino Mini Pro. It doesn't have inbuilt voltage regulator in the cicuit. So for that i have to use 12 Volts to 5 Volts Converter. What do you say , Sir?.
I integrated diode for blocking reverse current. I saw reference on internet. As per your advice i will try to do experiment as you mentioned. Thanks for that.
Prominis I have seen have an integral 5V regulator, rated for 150mA.
Wouldn't try getting that much current with 12V source tho, the regulator will get really hot.
Adding a reverse polarity protection diode is a good idea.
CrossRoads:
Prominis I have seen have an integral 5V regulator, rated for 150mA.
Wouldn't try getting that much current with 12V source tho, the regulator will get really hot.
Sir, That's what i am thinking about. It will get too hot. I am searching for some buck converter. Do you have any better idea ?
There are plenty of 12V to 5V DC-DC converters out there.
Here's an example:
