AVR-Chat

On Oct 15, 2006, at 3:01 PM, Ned Konz wrote:

> behrooz_hariri wrote:
>> The final contactor wich start/stop 3-phase motor and is connected to
>> a 5 volts relay on my AVR circuit board, cause spark and this has
>> negative effect on both AVR and specially LCD.
>>
>> Is there a circuit to diminish these electrical shocks?
>
> Yes. They're called "snubbers".

Another very basic thing I mention only because the original poster  
did not, place a diode across the DC coil on the relay. When one  
tries to turn off an inductive load the energy stored in the coil  
will kick back and try to keep the current flowing. A properly placed  
diode will conduct and dissipate this energy in an "infinite loop"  
before it gets back to your CPU.

--
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.