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Author Topic: mosfet amp needs help  (Read 1896 times)

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MrDEB

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mosfet amp needs help
« on: July 23, 2010, 18:01:10 PM »
I need to get this amp working. Built similar using TIP 41 and TIP31 transistors. Using the mosfets shouldn't have to worry about parts getting warm as I had one transistor getting hot, changed out and now it works fine
The pic input at R2 is a random square wave.
The junction of R1/R3 is 12v but using 9v (only voltage source I have presently for testing)
Q7 and Q8 are getting hot. Thinking the base resistor might be wrong? but having NEVER worked with Mosfets?
any suggestions
The resistor values were suggested by a knowledgeable individual.

kam

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Re: mosfet amp needs help
« Reply #1 on: July 25, 2010, 10:30:28 AM »
Have you try a resistor to the E of Q6?

MrDEB

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Re: mosfet amp needs help
« Reply #2 on: July 26, 2010, 16:37:20 PM »
Found several big problems
In orginal schematic I failed to connect the gates from Q1 to Q3
I revised the schematic as well as found the To220 pcboard layout was wrong
here are corrections. Hopefully everything is right.