This is my problem: I fed a signal between 0.4Volts to 0.6Volts to a 2N3906 Transistor. I could not switch on the amplifier. How would i deal with this?
0.4V-0.6V voltage is to low to switch on a transistor ..
Try to increase this control voltage to >1V and connect a current limiting resistor in the transistor's base (for 1V signal use 33Ω<R<100Ω) ..
This input signal is somewhat fixed because it is the output of the logic gates and will be fed to the said transistor..
Is it possible if we will put a comparator??
Usually, a logic gate output operate in wider range than 0.4-0.6V ..
But, if it is all you have you definitely need to amplify this signal and a comparator seems to be quite a good choice ..