Am trying to replicate another circuit as shown below and Q2 is suppose to be a BRX49 SCR. I have googled that this has 3 legs K, G, & A can someone tell me in the schematic where these legs are suppose to be connected? Still learning here on circuits.

Thanks

 

You just need to know where to look.

http://www.allaboutcircuits.com/vol_3/chpt_2/11.html