Drive motor with L293D and then it Burns ...............

[moodaeng]

Hi Guys 
      I am novice to motor control. I used L2 93 to drive 2 RC motors.
Then it  just burned out. I don't understand why this happened and how to fix the problem.
Do you guys have any ideads to test it?


Thanks

[Conscripted]

Do you have any more information about the 2 RC motors you used? It is very possible that you asked the L293D to provide more power then it was designed for. The L293D can provide 600 mA and up to 1.2 A peak. If you exceed that things don't go well.

Conscripted

[moodaeng]

I took the motors from my old lovely toy. :-(
How do i measure the current in motors?

If the current in L 2 93D is about 12 mA, this is a problem right?

I googled this problem. Can this problem be "Shoot through" short circuit?

Thanks

[SmAsH]

To measure stall current of a motor, get out ye trusty multimeter and set it to measure current.
hook it up accordingly for measuring current(as if in series) with the battery in like normal, hold the shaft still and see what the current draw is, this is your stall current, this is the max current your motor will draw.
so it will be:
(battery+)-(multimeter probe)  (multimeter probe)-(motor)   (motor)-(battery -)

The L293D drawing 12 mA is just how much current the chip itself uses to control the motors, how much IT uses.
You may have a short somewhere, but my money is on the motor drawing too much current.
You can probe around a bit in your circuit and look for some shorts if you want.

[radhoo]

This happened to me once, when I've tried to move a heavy robot - the motors couldn't run and short circuited my RC-toy h-bridge. Some smoke and the transistors were dead.

So better build you own h-bridge, is easy and you can use hi-power transistors (practically un-burnable):

See schematics on: http://www.pocketmagic.net/?p=508