Problem powering the core on the relay shield

Hey guys,

first of all, I have read all the topics that might be similar to my current problem. However, I could not solve the problem yet.

I got a Spark Core, Relay Shield as well as a wall wart. If I plug the wall wart into the relay shield by using 9V or 12V (it is adjustable) it works perfectly. Since I want to move on with my prototype I tried to replace the wall wart by using a PCB/ print transformer with the following specs:
Primary: 230V AC
Secondary: 12V / 833 mA / 10VA

To make a long story short, powering the relay shield as well as the core with the help of this transformer is not working at all. Unfortunately the Core is just flashing white and the green, red and blue leds are showing up. According to this topic Color Codes the core just initiated a Factory Reset. The relay shield clearly says 7 - 15V so it should actually work?!

Thanks in advance and best regards from Austria

If you’re just using a transformer, the output will still be unrectified AC. The shield only works with 7-15 V DC. Most wall warts output DC, so that is why that would work. If you are building your own power supply, you’ll have to rectify the output of the transformer, and probably have some capacitors/inductors for filtering the output.


Thanks @mumblepins for clarifying things!