Electronics > Beginners

Circuit design, lost on what's probably simple transistor logic

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blazini36:
Actually I made a pretty bonehead mistake there. I tried dropping the mosfets like you suggested with no luck, then I reaslized I was testing with a 2N7000 (TO-92) and when I updated the schematic I used a SMD 2N7002 because the board will use the SMDs. I didn't realize that the source and gate pins swapped  |O. Hopefully this makes a little more sense. I'm using the 2N7000 because it's what I have on hand to test. I have a box of assorted transistors coming in today so if there is a better alternative I'm all ears but so far this is what I've gotten to work.

Updated schematic.

Wimberleytech:

--- Quote from: blazini36 on December 04, 2018, 04:12:11 pm ---Actually I made a pretty bonehead mistake there. I tried dropping the mosfets like you suggested with no luck, then I reaslized I was testing with a 2N7000 (TO-92) and when I updated the schematic I used a SMD 2N7002 because the board will use the SMDs. I didn't realize that the source and gate pins swapped  |O. Hopefully this makes a little more sense. I'm using the 2N7000 because it's what I have on hand to test. I have a box of assorted transistors coming in today so if there is a better alternative I'm all ears but so far this is what I've gotten to work.

Updated schematic.

--- End quote ---

Better.  However, when the mosfet is off, there is nothing determining the potential on PWM pin.  It needs a resistor pullup to 5V.

blazini36:
Any Better?

Wimberleytech:

--- Quote from: blazini36 on December 04, 2018, 05:15:29 pm ---Any Better?

--- End quote ---

That oughta do it!!

blazini36:
Thanks for the help bud. :-+

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