I am really struggling to understand how this circuit works theoretically. What will be the currents through the resistors? My understanding (which I suspect is wrong) is as follows:
Ir1 = (7-0.7)/100 = 63mA (B-C is forward biased)
Vemitter = 7 + 0.7 = 7.7V
Ir2 = (12 - 7.7)/1k = 4.3mA
Vcollector = 7 - 0.7V = 6.3V
Ir3 = 6.3/1k = 6.3mA
Now, what confuses me the most is the zener diodes. What is their purpose in the circuit? I have not made use of them in my calculations. Could someone please help me understand this circuit? Thanks!