AVR-Chat

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? 

Thanks
Behrooz Hariri

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".

Google for [relay snubber]

Are you using an isolated solid-state relay?

-- 
Ned Konz
ned@bike-nomad.com
http://bike-nomad.com

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.

???

You should not even have that relay powered from your logic supply, put 
that relay on another power rail and (of course) control it with a 
transistor.

DLC

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? 
> 
> Thanks
> Behrooz Hariri
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 


-- 
---------------------------------------------------------------------
* Dennis Clark  dlc@frii.com http://www.techtoystoday.com             *
* "Programming and Customizing the OOPic Microcontroller" Mcgraw-Hill *
---------------------------------------------------------------------