Hi
Im making a H-bridge for my school projekt. It will power a 12V 3A motor.
Q1 and Q4 are Tip127 5A PNP transistors Hfe = 1000
Q2 and Q3 are Tip112 5A NPN transistors Hfe = 1000
(Multisim dident have them)
First problem:
Will this H-bridge work? The inputs are a comparetor with Isource max = 60mA and 5V.
Second problem:
I found R3 and R4 this way:
Ib= Ic/Hfe = 3A/1000 = 30mA
Rb= (Vin-VbeQ2-VbeQ5)/Ib = (5-0,7-0,7)/30mA = 1,2KOhm (dont mind the wrong value in the pic.)
Is this right??
Third Problem:
R2 and R3 are parallel so same voltage but i dont know how Big I is over R2 and how to calculate R6. My teacher said something about a voltage drop over R6 so Q4 would turn on!
Thx for you time, Dennis!
!!! EDIT !!! Gain for BC547A is 100!
Im making a H-bridge for my school projekt. It will power a 12V 3A motor.
Q1 and Q4 are Tip127 5A PNP transistors Hfe = 1000
Q2 and Q3 are Tip112 5A NPN transistors Hfe = 1000
(Multisim dident have them)
First problem:
Will this H-bridge work? The inputs are a comparetor with Isource max = 60mA and 5V.
Second problem:
I found R3 and R4 this way:
Ib= Ic/Hfe = 3A/1000 = 30mA
Rb= (Vin-VbeQ2-VbeQ5)/Ib = (5-0,7-0,7)/30mA = 1,2KOhm (dont mind the wrong value in the pic.)
Is this right??
Third Problem:
R2 and R3 are parallel so same voltage but i dont know how Big I is over R2 and how to calculate R6. My teacher said something about a voltage drop over R6 so Q4 would turn on!
Thx for you time, Dennis!
!!! EDIT !!! Gain for BC547A is 100!
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