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inverter output corrupted help!

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MrDestruction

New Member
Hey guys, can u tell me what you think might be the problem with this output of my mosfet transformer circuit. I also displayed the output in my attached images. Do you think its because of the BJT's to slow switching time.

Anyways let me know what you guys think.

later guys and girls.

Mr. D.
 

MrAl

Well-Known Member
Most Helpful Member
Hi,

MrDestruct, your profile shows pictures that are very hard to read.
You should do them over making them larger and clearer.
You should also post them in this thread for easier viewing.

I can tell you right off that you are not driving the bipolar transistors
correctly but i would rather look at a larger schematic first.
 

audioguru

Well-Known Member
Most Helpful Member
The schematics were saved as a very fuzzy JPG file type instead of as a very clear GIF or PNG file type.
 

MrAl

Well-Known Member
Most Helpful Member
Hi,

Yes i found that rather strange too :)
 

MrDestruction

New Member
my intention of this circuit was to see mosfet H bridge to drive a step up transformer. So i used bjt transistors to switch the mosfets. this circuit is not for building, its for simulation.

If the problem is switching time then i have reached my simulation. because i can't simulate the mosfet driver yet as i am still working on the circuit for it.

just wanted to know what was wrong with the output.
 

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MrDestruction

New Member
My bad guys, here it is let me know what you think. i know the transistors are bad choice to drive H bridge mosfets but i just needed to simulate ac curve at transformer output.

Thanks,

Mr. D.
 

MikeMl

Well-Known Member
Most Helpful Member
Its not the transistors; they will discharge the FET gate capacitance when they turn ON. What is wrong is how long it takes to charge the FET gate capacitance through the 1K pullup resistor when the NPNs turn OFF.

You also need a series resistor between the op-amp outputs and the bases of the NPNs.

Why not use a real gate driver like this one for the low-side gate driver. Poke around on TI's web site. They make a high side driver too. Then you can lose the op-amps.
 
Last edited:

MrDestruction

New Member
In actual circuit development, i will be using mosfet driver, but this is a simulation environment, just trying to get a square wave H bridge transformer output. I do not have a mosfet driver simulation model that i can use for this so i used transistors to switch the mosfets.

what do you think i should add to the schematic to remove this saturation. i will add 4.7K Resistors at the base of the transistor but i don't how that will help.

thank you for your help btw.

Mr. D.
 
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