Guiding students to answers is generally preferred. They're likely to retain the information longer if they have to work to get it..."The action described happens very quickly as the switching on of Tr2 by Tr1 is a form of positive feedback with each transistor collector supplying large current changes to the base of the other."
http://www.learnabout-electronics.org/diodes_06.php
That's the problem as I see it. OP didn't say what they had done to research the problem. S/he simply asked for an answer and got one. If they won't bother to try to do a Google search and go through the results to find something that makes sense, or doesn't, before asking for assistance; they're just looking for someone to do their homework for them. We shouldn't do that...but they will look a little deeper prior to coming here ... at least that's my hope.
Perhaps the TS can simply have you do all of their homework for them."The action described happens very quickly as the switching on of Tr2 by Tr1 is a form of positive feedback with each transistor collector supplying large current changes to the base of the other."
http://www.learnabout-electronics.org/diodes_06.php
We know. The real problem is that the OP didn't even expend the effort to Google it...It is just google.
That being the case, then it might be better to give them a phrase worth Googling and let them at least try to go from there.It is just google.
by Duane Benson
by Jake Hertz