I am working on a project of security alarm system using a PIR sensor. I wanted to connect a siren to a arduino UNO i have selected pin no 4 as output to the siren , I have used BC547 transistor for switching a siren ON when the motion is sensed , the code for the project is also working fine, i have tested using led instead of siren everything works fine.
when i connect the siren the siren starts to sound continuously it should work only when the output of pin 4 is HIGH .
The siren used is 12V ,300mA.
I have connected the siren between to 12V supply and emitter of transistor and to the the base the output of pin no 4 is given. the collector is connected to to the ground of 12v supply.
d to the the base the output of pin no 4 is given.
No resistor?
It needs to go through about 1K before it gets to the base.
Have you connected the -ve of the 12V power supply to the ground of the arduino?
Actually i showed only how i have connected siren instead of led when i connect siren instead of with a current limiting resistor it only reduces the amplitude of sound. the 12v supply i have taken from the connector which is present on the arduino uno.
I don't understand what more you want from this thread. Get a proper transistor and try again.
It is pointless giving you a type because I don't know where you are or what are available to you.