Can anyone help me how connect this two circuit.Actually the operation is when the ultrasonic radar circuit which is already connected to siren circuit that i inserted in this thread is detected a motion, the output from TR1 in Ultrasonic Radar circuit will activated the siren circuit...How i can make this Strobe light circuit can activated simultaneously with siren circuit when get trigerring from TRI from Ultrasonic radar circuit...

 

Connect the Cathode of an Opto to the collector of TR1 and use a relay coil in the Opto transistor's collector. Then connect the AC line in series with the relay contacts.

 

The original ultrasonic circuit already had a darlington pair of transistors driving a relay.

 

i cannot understand so much because my english is not good...can you draw to that circuit i inserted...thank you very much if u can help me...

 

Did you investigate what Audioguru said in post 3?

 

This is what I was describing to you. The components shown on the Strobe board are existing components. Please don't kill your self!