Electronic – how to use a 3v output to control a 5v relay


I have some circuit where my board (Electric imp) can output up to 3.3v,
and i need to control a relay with atleast 5v in order to effect the coil and close the circuit.
i have a power supply of 5v, so i was thinking maybe using a transistor with gate connected to my 3.3v signal, and somehow to control the transistor to push the 5v power supply to the relay.

but how? the only idea i had is making an inverter, wiring 5v to pmos, pmos drain to vout, and also nmos to drain and from there to GND.
and then when 3.3v -> vout = 0, and when 0v -> vout = 5v.
not exactly 5v, because i i need to know Vsd

Best Answer

Surely you can just low-side switch the relay with a regular transistor?

Edited for the hard of goggling:

Low-side switching circuit

Transistor can be 2n2222, 2n3904, etc.