Hi guys. New to the forum, got a quick question... So the attached image is a modified version of a circuit that SgtWookie posted in this thread:
http://forum.allaboutcircuits.com/showthread.php?t=33116
Oh and sorry for the new thread, apparently the old one is too old to be bumped... So anyway, looking at that circuit, I have a few questions:
1. Since Q2 is used to pull the gate Hi, what purpose does R5 serve...? I can't understand why S.W. included it; when I delete it and run the simulation again, nothing changes.
2. What purpose does D1 serve...? I can't figure it out. I know it's necessary, I just can't figure out what it's doing. Just toying around and doing some trouble shooting, when I replace the diode with a piece of wire, and run the simulation again, suddenly the gate voltage is VERY slow at going Hi. This can be seen in the second image - notice how the gate voltage lags at pulling up. I'm sure this has something to do with the gate capacitance, I just can't figure out what's happening.
Any help would be greatly appreciated!!
http://forum.allaboutcircuits.com/showthread.php?t=33116
Oh and sorry for the new thread, apparently the old one is too old to be bumped... So anyway, looking at that circuit, I have a few questions:
1. Since Q2 is used to pull the gate Hi, what purpose does R5 serve...? I can't understand why S.W. included it; when I delete it and run the simulation again, nothing changes.
2. What purpose does D1 serve...? I can't figure it out. I know it's necessary, I just can't figure out what it's doing. Just toying around and doing some trouble shooting, when I replace the diode with a piece of wire, and run the simulation again, suddenly the gate voltage is VERY slow at going Hi. This can be seen in the second image - notice how the gate voltage lags at pulling up. I'm sure this has something to do with the gate capacitance, I just can't figure out what's happening.
Any help would be greatly appreciated!!
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