Problems, designing a switch in multisim I want to make a radio operated trigger

[VikthorasH]

Hello there, I want to design a switch, using either, a power relay or a tranzistor. So that a small battery 3.7 volts, when the circuit is connected, would act as a switch, to close the circuit, for a 12 volt, battery. I want to design this, as a distance radiocontrolled device. But I do not know how I should use the tranzistor or power relay... If anyone could give me a helping hand, advice, model, would be much appreciated, here is a picture

[VikthorasH]

And a video of what I want to accomplish

https://www.youtube.com/watch?v=uo7uFym7Urw