Implementing a spst relay

Question

I am new to electronics, with minimal circuit knowledge, and I am trying to build something that does the following:

^{simulate this circuit – Schematic created using CircuitLab}

I have a power cable that is outputting 12 V and about 10A. My goal is to design a relay into that cable, that will cut the power supply if the arduino supplies 0 V and will do nothing to it if the arduino supplies 5V. I have been told to look into solid state relays, but they are expensive and I was wondering if I could just use a simple SPST. My only issue is that the arduino can only supply ~100 mA, and I want the device to not fry when it has 10 A on it.

Answer 1

You can easily get a "regular" electromechanical relay with sub 100 mA coil current and 10A contacts, but you can surely use the sub-100 mA current to turn on a transistor that can turn on the coil of a mechanical relay with 10A (or greater - greater is a good idea for longevity) contacts.

Then again, depending what you are doing, simply a transistor might do what you need.

^{simulate this circuit – Schematic created using CircuitLab}