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Grid stopper resistor question
Grid stopper resistor question
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Old 17th September 2019, 02:53 PM   #41
DF96 is offline DF96  England
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Originally Posted by SemperFi
Can a cathode follower oscillate the same way?
It is well known that all followers are prone to oscillation, especially with a capacitive output load. The usual solution is an output stopper, to isolate the output from the capacitance. Inductance does no harm.

To me I see no reason not to place the gridstopper right at the pin, and the reason is to limit unwanted inductance, as well as having a logical and consistent place to have it.
Yes, put it at the pin. But not for the reason you say.

It may be rules of dumb but I have had MF gridstoppers open up after over-drive in guitar amps. CCs have never failed, they are simple the most tolerant resistor types. And the horrid drift doesnt matter in this application, so I see no reason not to adhere to this rule made up by much wiser men than me.
When following a rule made up by wiser men it helps to know why they invented the rule; then you will know when you don't need to follow the rule. CC resistors are good at coping with temporary overloads, so they may be useful in a guitar amp output stage suffering from heavy overdrive. This reason does not apply to hi-fi, so there is no need to use CC stoppers elsewhere.
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Old 17th September 2019, 03:23 PM   #42
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
Clapp and Hartley oscillators can use a follower.
Osvaldo F. Zappacosta. Electronic Engineer UTN FRA from 2001.
Argentine Ham Radio LW1DSE since 1987.
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