Ethernet shield W5100 - freezing/resetting when relay on/off

Using Arduino Networking, Protocols, and Devices
1

Hi,

I trying solve my problem several days without success. I have read several topics on same/similar problem, but I have not found solution.

I am using Arduino UNO with Ethernet shield R3 (W5100) and relays board. Relays board and Arduino have separate power supply without shared GND. On Arduino is running server on port 80, which waits for commands from client.

When I toggling relay on PIN4 without any AC 230V, everything works OK. But when I connect load - light bulb on 230V, then Ethernet shield randomly resets/freeze. So ethernet shields respond on ping, but connect to server is not successful.

Video here:

I tried another relays board, another Arduino UNO - without success.

Thanks for help.

code.ino (9.58 KB)

2

keyword is EMI. google solutions

3

Ok. I have read something about It. But Why there is not EMI when I toggling relay without load?

Thanks.

4

kuba1999:
Ok. I have read something about It. But Why there is not EMI when I toggling relay without load?

Thanks.

because the AC the circuit is then not connected. no current, no spark