I've got problem with my arduino project... I've created a ventillation system controller, which turn on the ventillator once a day, or if humidity is more than a presetted value.
For this I use a Songle SRD 05 VCD relay. If I test the equipment without 220V DC connented to the relay, it works perfectly. But If I put it into operation and connect 220 V DC, when the relay switches, LCD starts to show random points/characters. (but other things work perfectly e.g. clock, it turns off and on if I press the buttons, so it seems only the LCD has problem...) In some cases it happens at the first switching, but somtimes it works fine a few times, and than goes wrong. :(
I've tried with different power sources: 9 V 600mA, 9V 1000mA, 12 V 1500mA. I've tried to supply the relay with different power source (batteries) with common GND, but it works the same way. I don't know what culd be the problem... I assume something like noise or stray current...
Thank you in advance!