Rookie - start over

Sorry,

I try to explain again.

I'm trying to activate a relay from the output of Arduino UNO

The relay is 12 Volts and I have other of 9 volts. The transistror I use is a 2N222A and I do not know that put in emitter resistor

I've tried everything and no way to activate the relay coil . If is activated, then there is no way to disable

The program with leds works correctly.

Someone has the outline of a circuit to do this.

thank you very much

Miquel

I do not know that put in emitter resistor

what does that mean, please?

What is the base-emitter resistor should I wear?

thank you

cargol:
What is the base-emitter resistor should I wear?

thank you

How much current does the relay you intend to use need?

Does this article help?

here

Perfect, Tested and working.
You've been very helpful.
Greetings from Catalonia
Miquel