January 29, 2017 at 6:30 pm #22829
There are quite a few different solutions. The right one for you will depend upon factors including the speed that you require, the current carrying capacity, and so forth.
Depending on your application, you might be able to just use a transistor instead of a relay.
You could use a solid state relay, that can be driven directly from 3 V.
You could use a mechanical relay, that can be driven directly from 3 V.
You could use a transistor to drive the coil of a relay that requires higher voltage and/or current.