Transistor without base resistor

Thread Starter

vivek20055

Joined Nov 4, 2012
88
Hi,

why base resistor is used for transistor. what happens if base resistor is not there for a transistor?



Best regards,
Vivek Alaparthi
 

DickCappels

Joined Aug 21, 2008
9,508
Some bipolar transistor circuits (such as common bases and common collector, and those that drive the transistor with a high impedance, such as the collector of another transistor) do not need a series base resistor to limit base current, but would use a base resistor to reduce the Q of the base circuit so that it won't oscillate at radio frequencies. Another use, particularly if there is appreciable capacitance between the base and collector in a common emitter circuit would be to control the rate of change of the collector voltage. There are probably a few other reasons one would use a base resistor, but there are some.
 

wayneh

Joined Sep 9, 2010
17,189
Is it possible that the two base signals are current-limited somewhere else? If not, it's just wrong and will burn up.
 

DickCappels

Joined Aug 21, 2008
9,508
Some transistors that have internal series base resistors so that they can be turned on and off with control voltages without an external resistor. Such resistors are unusual, but they are exist.
 
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