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Topic: Obstacle deteccting robot-Motor speed low (Read 123 times) previous topic - next topic


I'm working on an obstacle detecting robot using infrared sensors
I'm using 2 9V dc motors(with gearbox) and powering the motors as well as the arduino using 9v battery.I am using the L293D Hbridge.
When the motors are not connected to anything..just the battery...it runs really fast..but once on the circuit it runs slowly(connected to hbridge).
I understand there will a potential ddrop of around 2v across the H-bridge.However..when i connect a 5v source to the arduino..and remove the motor  power source(pin 8 of l293d) it stills runs at the same speed.
Does this mean my motors are drawing current from the arduino?
Why is that with both 5v and 9v supply the motor speedd is the same!
Any help would be much appreciated
Have a good day :)


However..when i connect a 5v source to the arduino..and remove the motor  power source(pin 8 of l293d)
I don't understand that.

The small PP3 style 9v batteries are completely unsuitable as they can't supply enough current.

It would be best to have separate power supplies for your Arduino and for your motors.

If you want more advice please post the program you are using. If it is part of a larger robot program it would be helpful just to write a short motor-control program for testing / learning purposes.

Two or three hours spent thinking and reading documentation solves most programming problems.


Don't run the motors from the Arduino supply like this, the motor power needs to be present
whenever the inputs are active.

The small 9V batteries will not power a motor, servo, or relay satisfactorily.  You need a higher
current supply.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


What sort of power supply are we talking about?

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