Hello,
I want to control a 3-6v dc motor using a L293D motor driver. Will it be a problem for the motor if i connect a 9v battery to the motor driver as power supply? Also would i need to limit the power by not setting the enable pin to it's full 5v but like 3v or something, or is the motor protection from the driver good enough that i can put the enable pin to it's full potential?
Also, just a curiosity question: if an external power supply is connected to the arduino, powering a dc motor via the arduino board itself (5v pin, ofcourse not i/o pin) is a bad idea right? just way to much current, at least to for starting the motor.
Please let me know!
thnx
If you mean a 9V PP3 block battery, you will find that they cannot provide enough current for most motors. Those are for very low power consumer devices like smoke alarms.
Brushed DC motor voltage ratings are nominal. They run faster at higher voltages, but that lowers their expected lifetime. Use a motor controller to run them at lower average voltage and speed.
Yes very bad idea.
Will it be a problem for the motor if i connect a 9v battery to the motor driver as power supply?
It depends on the motor
Also would i need to limit the power by not setting the enable pin to it's full 5v but like 3v
The enable pin just turns the motor ON/OFF. it does not control the power to the motor. You either set it to 5V or 0V
Oh, I just saw a video of an Asian guy explaining that this pin could change the speed of the motor by changing the voltage. I checked the data sheet and it indeed seems like it just reads high or low, thanks for the clarification!
So if i can't use a 9V battery, but also can't power it trough the arduino board with an external power supply. Then how power it? I need a power module for that i guess?
That will depend on the motor. Many people power little hobby motors with a 9V battery.
What kind of motors do you have?
It might look like the voltage was changing, if he measured it with a multimeter. But in reality, Pulse Width Modulation (PWM) is almost certainly used to switch between 0V and 5V rapidly. During each cycle, the amount of time at 5V can be varied compared to the amount of time at 0V. This will affect the motor's speed, and give apparently different voltage readings on a multimeter, because multimeters cannot measure rapidly changing voltages, and will give (if you are lucky) an average reading of the voltage.
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Aah ofcourse, that makes a lot of sense. Yeah he indeed used PWM from the pins.
Thnx
Yeah i have like the most simple variant, it's like 90 cents.
Here are some specs:
Voltage: 3-6V
measurements: 28 x 15 x 20mm
nominal: 3V, 0.35-0.4A
3V velocity: 20000 r / min
6V velocity: 40000 r / min
A 9V can supply the current, it just won't last very long, maybe 3 or 4 hours if you run it continuously.
6AAs would last longer
Two 3.7V Li-Ion batteries in series would also be good
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Alright, thank you so much!
I just want to run some small tests so it's doesn't need to run long.
but you don't think the 9V will be a problem then?
Because i could also use 4 AA's in that case to stay below 6V
A PP3 block battery won't work, but 4xAA (6V) or 6xAA (9V) will provide enough current to run the motors.
The ancient L293D motor driver is very inefficient, and wastes 2 to 4V internally as heat, so your motor won't see the full battery voltage in any case.
Pololo has a great selection of modern, much more efficient motor drivers. This one is an excellent choice for your motors.
So you have 3 options, the 9V alkaline, 4AA and 6AA
The L293 will drop the voltage maybe 2V so with the 4AAs the motor will see 4V, with 6AA it will see 7V. The 4V is within the motor specification the 7V is a little high but shouldn't hurt.
Of course with 7V it will run faster.
The 6AA will last the longest, the 4AA next and the 9V the shortest
@when_in_doubt_use_400v
Glad I could help
Have a nice day!
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