Electronic Devices and Circuits - Engineering

Q1:

From the given circuit below, we can conclude that.

A BJT is pnp

B BJT is npn

C transistor is faulty

D not possible to determined

ANS:C - transistor is faulty

According to figure, both the LED is glowing, which indicate that circuit is complete in both the half cycle of a.c. signal. Therefore Emitter and Base junction will act as short circuit in both direction, which indicate transistor is faulty.