Arduino relay driver circuit

[Vikrama Chandar]

Hey everyone...i just signed up on this forum and i'm not aware of how to use it. But my question is a little simple one. As u see in this given relay driver circuit, there is a diode which is connected paralell in reverse bias. What is the use of it???

Thanks in advance

 

[Arouse1973]

The diode protects the transistor from the potentially high fly-back voltage produced by the relay coil when the relay switches off.
Thanks
Adam

 

[Vikrama Chandar]

Thank you once again Mr.Adam.

 

[Arouse1973]

No problem, Adam's just fine not Mr Adam

 

[SalRu]

Yes it's for protection.

When you switch of the relay, the diode avoid current to flow through the NPN and damage it

By!