Recently, I got a new 5 Vdc Power supply 3A to power my arduino uno + ethernet shield but there is something going on I cannt explain.
When I use the power supply to send signal to a 5vdc relay, it powers it up to it does not click ( common to N.O.) contact even though the led blinks, showing a change of state.
When I power it up with a USB from my computer it works fine...
I measured output voltage from the USB and power supply: both send 5 Vdc but it seems that the power supply is not to the taisk.
I also noticed that the on LED from ethernet shield is a lttle dimmed when powered by the external power supply.
Does this ring a bell to somebody?
Your comments are very welcome.
Thanks in advance. :o