AVR-Chat

> -----Original Message-----
> From: Joe [mailto:joet@attg.net] 
> Sent: Tuesday, 10 February 2004 3:40 PM
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] Relay Control
> 
> 
> I am using a Atmega16 running at 7.37Mhz.  
> 
> I am also using a LCDPlus. I talk to it with the Rs232 Hardware UART. 
> It has a ULN2803A with 8 relay Darlington Drivers. This also includes 
> blocking diodes. I am using 5v Relays with contacts rated at 250v 10a.
> 
> The setup uses a momentary button to interrupt on Int0. The relays 
> energise Mains contactors 120v 1a and ring a bell 120v .6a.
> The system works fine with no load on the relay contacts. 
>
> When I connect the contactor and bell I get false interrupts. I can 
> software out the problem by disable/enable Int0 before and after the 
> relay call. But I would like to fix it.
> 
> What I have done:
> Use 1 supply for relays and 1 for the AVR.
> Adding a power line filter before the power supplies.
> I used a car battery and a dc to ac inverter to Isolate the unit from 
> the contactor power.
> 
> So far no real fix.
> Any Ideas??
> 
> JoeT

Ground plane for the PCB, Shielded metal box for the PCB, a snubber
network on the contactor, a pull up resistor on int0 pin (1K).....

This is a common problem, with lots of answers, the above is just a
start.

Regards,

Kat.

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