why my output getting like this

samuel.sam77 · Apr 17, 2012

hi all i am using pic uC to get pwm output but the output is not quit well help me wer is the problem

the output is given to the h bridge ckt to drive pulse transformer

Nigel Goodwin · Apr 17, 2012

You shouldn't use NPN transistors for the top ones, you don't have enough drive voltage to turn them ON.

samuel.sam77 · Apr 17, 2012

base volt is 5v ...and collector voltis 15V

Ian Rogers · Apr 17, 2012

samuel.sam77 said:
base volt is 5v ...and collector voltis 15V

The two top transistors emitters are higher than 5V... When the bottom transistor is OFF the emitter is floating... It can't really earth through the transformer..

Nigel Goodwin · Apr 17, 2012

samuel.sam77 said:
base volt is 5v ...and collector voltis 15V

And the emitter will only be 4.3V - providing little voltage to the motor, and wasting LOT'S of heat in the top transistors.

be80be · Apr 17, 2012

The whole thing is wrong. He switching the same side and sending the same pwm to both side never work.

What are you trying to do any way with the transformer.

This is with a 555 but you can use a pic
View attachment 63438

This may be what your after read it I has some real good stuff about how to get true AC from DC https://www.electro-tech-online.com/custompdfs/2012/04/MQP_D_1_2.pdf

View attachment 63439

why my output getting like this

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why my output getting like this

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