AVR-Chat

At 02:08 PM 8/3/05 +0200, Ralph Hilton wrote:
>On Wed, 3 Aug 2005 12:31:14 +0800 (CST) you wrote:
>
> >
> >Dear All,
> >
> >Kindly advise how to use optocoupler 4N25  to isolate microcontroller 
> minimum system to Contactors :
> >
> >1. Output from Port 0.0 to Optocoupler
> >
> >2. Ouput from Optocoupler to drive contactor
> >
> >Questions :
> >
> >1. What should i do with the base pin of the transistor
> >
> >2. What is the value of the pull up resistor to drive 12V DC to contactor
> >
> >Please comment.
> >
> >Thanks
> >
> >Mansur
>
>How much current does the "contactor" need?

Indeed, the devices I refer to as contactors usually draw from 800ma to 
over 3A to pull in the tips.  Well over the rating of most optocouplers.  A 
simple reed relay on the other hand...

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
they legal, genetic, or physical.  If you don't believe me, try to chew a 
radio signal. "  -- Kelvin Throop, III
http://www.aeolusdevelopment.com/