AVR-Chat

On Wed, 03 Aug 2005 11:10:23 -0400 you wrote:

>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...

ok, it is good when you want a meaningful answer to give as much data as possible.

How about using a logic level MOSFET?


--
Ralph Hilton
http://www.ralphhilton.org
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