Hi David,
I will check that, I did run the motors with a seperate
6AA supply and they ran OK. I was trying to eliminate the
extra batteries and associated weight.
I will search the archives for Romans old post,
I just like the simplicity of the L293d :)

>At 07:50 PM 19/08/2002 -0500, you wrote:
>>Hi,
>>I am driving two small DC hobby motors in a gear box assembly,
>>that drives two tank tracks. I wanted to power the F628,
>>SN754410 and two motors all from the same 4AA batteries.
>>If I drive the two motors right off the 4 AA batteries,
>>the tank tracks are powerful and can drive over a thick
>>book.  However, when I power the pic/SN754410/2 motors,
>>the motors are barely able to turn the tracks ?
>>
>>In the F628, I have port A set as digital, and set ra1, and
>>ra0 high and low to turn on motor a, and follow the same for
>>ra2 and ra3, for motor b (through the SN754410 of course.)
>>The SN7554410 is just a 1 amp version of the L293D.
>>port b is set as output and all pins low.
>>
>>I quess I'm just looking for a sanity check, I can't believe
>>the F628 and H bridge chip are using up so much current
>>that the motors can't even turn the tank tracks ?
>>I have both enable pins on the h-bridge chip tied to the +5v
>>supply through a 10k resistor.
>>Any one familiar with these chips ?
>>Any thoughs on what's happening ?
>
>It might be that the saturation voltage of the L293 is causing
>less than 6V to be applied to the motor. Have you measured it?
>The L293 sucks pretty badly when you only have a low battery
>voltage to start with as the saturation (drop across output drivers)
>voltage is quite a high percentage of the available supply.
>Roman suggested some better H-Bridge drivers some time back.
>Regards...
>___________________________________________
>David Duffy        Audio Visual Devices P/L
>U8, 9-11 Trade St, Cleveland 4163 Australia
>Ph: +61 7 38210362   Fax: +61 7 38210281
>New Web: www.audiovisualdevices.com.au
>___________________________________________
>
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