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What is the purpose of this FET?
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Axtman
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Feb 2007
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#1
What is the purpose of this FET?
06-28-2023, 05:25 PM
What is the purpose of the FET (Q5) in the following circuit? Pin 3 is the input to the amplifier (U2)..
Axtman
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#2
06-28-2023, 05:26 PM
Here is the full schematic:
crate_tx_15_sch.pdf
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g1
Don't forget the joker
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#3
06-28-2023, 08:14 PM
Looks like a mute Fet. C19 takes a bit of time to charge at turn on. Q5 shorts the signal to ground until C19 is charged.
Originally posted by
Enzo
I have a sign in my shop that says, "Never think up reasons not to check something."
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The Dude
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#4
06-28-2023, 09:21 PM
^^^^^^^ Yes, that!
"I took a photo of my ohm meter... It didn't help." Enzo 8/20/22
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Axtman
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#5
06-28-2023, 09:45 PM
Thanks guys!
The TDA-7240A is such a small wattage amplifier I would not think it would mind being slammed with a signal right away.
Maybe this has something to do with removing popping sound. Buth then the speaker is small and I would think a small pop wouldn't hurt them.
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patlaw
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#6
06-28-2023, 09:49 PM
It's slow to unmute and quick to mute (when the power is removed.)
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