Relay shield: interference suppression needed

Hello Forum members,

When I switch bulbes the relay shield works fine. When I switch orkli 40310200 2 way valves I get electrical interference. the DS18D20 (temp measurement) and the display (MOP-AL204A-BBTW: LCD 4x20 blue, gets disturbed 3 of the 10 times. The relay shield and Arduino itself keep on working correct.

What can I to make my project work without problems?

With kind regards
Ron Groen
The Netherlands

I finally found the solution. It is the relay board itself. With an other bord a Opto-Isolated 8 Channel Relay Board everything works fine! … tail&p=156

PS It looks as if the Seeeduino relay bord gives a wrong volate to the Arduino board.