AVR-Chat

----- Original Message ----- 
From: "behrooz_hariri" <behrooz_hariri@yahoo.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Monday, October 16, 2006 10:43 AM
Subject: [AVR-Chat] AC contactor surge affects MCU


> AVR switchs on/off a 5V relay using ULN2003. The relay commands to
> 220V AC contactor, which finally runs motor pumps.
>
> All the circuits are placed in a metal box, and as far as I see, the
> spark from contactor coil disrupts LCD display or MCU itself.
>
> I used a serial RC in parallel with contactor coil, which lower spark
> effectively. Yet this is not enough. What elese can I do?

Use a transient suppressor like an AVX TransGuard on the Vcc supply. I 
always use them on boards that are operated in noisy environments, and don't 
have any problems.

Leon