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### Topic: can I control a 4.4A DC Motor using a L293D? (Read 802 times)previous topic - next topic

#### _emanuele_

##### Jun 20, 2015, 12:20 amLast Edit: Jun 20, 2015, 12:51 am by _emanuele_
Hi all,
I'm working on a little robot with Arduino, but I'm having some issue with the DC motors.
I'm new of the Arduino/electronic world so please forgive me if I say something stupid.

I first used two Hobby Motor 130 Size, but they where not enough powerful.
The wheels were moving on "free wheel" but once I put the robot down they stopped.
I did't want to use geared motors to keep the cost low and because the (3d printed) robot already has a 1/10 gear reduction.
So I decided to try with this motors: http://ie.rs-online.com/web/p/dc-motors/2389721/
There were others with a more reasonable power, but they were not in stock, so I took the risk...
I know the L293D can give just 0.6A (1.2A peak) but I though with the pwm I could reduce the power and make them work without burning everything and eventually try with the L293D "piggyback".

With some calculation I got a pwm of 255*0.6/4.4 = 34
I used 30 to be safe, but the motors didn't move.

I increased gradually the pwm but nothing...they won't move.

I'm using a different powers supply for the motors (I tried with 4xAA and 6xAA).
I also have for each motor three 0.1uF capacitors connected between the two poles, and each pole and ground.

The question is: is it theoretically possible to drive a 4.4A motor with 0.6A (or 1.2A) ??
My expectation was to be still able to make them move but of course not get 375 gcm of torque.

DC Motor technical info:
Current Rating   4.41 A
Maximum Output Torque   375 gcm
Power Rating   19.68 W
Supply Voltage   3 → 7.2 V dc

#### MarkT

#1
##### Jun 20, 2015, 01:43 am
No, not the right motor at all.  Go for higher voltage and lower current and you'll have a match
to a low current motor driver like the L293.

Theoretically yes, you can measure the current from PWM cycle to cycle and keep it
within bounds, but then you'll just have a very complicated way of having an underpowered
motor.

Go for higher voltage motor and supply, or give up on a low current motor driver and get a
MOSFET board with good current ratings.  Your motor's stall current is probably in the 15 to
20A range I would hazzard a guess, that's the sort of rating a motor driver for it needs.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### Isaac96

#2
##### Jun 20, 2015, 04:45 pm
If you want to piggyback L293Ds, you will need 7 on top of each other. That will be a tall stack! You could try using the L293 to drive MOSFETs.
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

#### Zapro

#3
##### Jun 21, 2015, 02:20 pm
To drive that motor you need what is called a "brushed ESC" - like this (the cheapest i could find on eBay)

// Per.

#### MarkT

#4
##### Jun 22, 2015, 12:52 pm
Or one of the Polulu MOSFET H-bridges.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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