12V-9V Converter for Arduino

[Jaderman]

Wow when I pasted it on the messaging it was LONG and I was worried that it wasn't going to turn it into a link, but whatever.

 

[Resqueline]

The ones you suggest there are rated at 40A and draws quite a lot of current to the coil. I had 8-16A relays in mind which draws much less power.
5th: 5V/14ohms=357mA. I don't remember exactly if the Arduino can drive this much. Check spec's.
6th: 12V/90ohms=133mA. Being 12V the Arduino needs an open-collector output to drive this one. Check spec's.