3904 NPN transistor to drive a relay

[Roff]

I am positive. I also interchanged the base and collector. The relay does not get triggered at all. SO I think I have the transistor wired properly.

It's collector and emitter swapping that will give you marginal results, not collector and base.

 

[kurrodu]

Ron,

Now I realized that the circuit works fine as long as there is no load attached to the relay.

The load that I have is 240VAC 40Watt bulb.

I think there is noise that is being generated. So do you think there would be any protection circuit for this?

My friend asked me to look at weber circuit.

 

[kurrodu]

Thank You all

Finally, I have used an opto coupler MOC 3021 and a triac Bt139 that solved my problem.

Thank you all for the support.

 

[Tom81]

I know this post is a few months old now BUT... I had a similar problem a while back - https://www.electro-tech-online.com/threads/driving-relays-using-pic-16f88.97988/

Opto coupling is definitely the way to go for reliability, although if this is not an option (IE too expensive) have a look at the above thread. Might give you some ideas.