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-   -   Stability of an amplifier under capacitive loading (https://www.diyaudio.com/forums/solid-state/359704-stability-amplifier-capacitive-loading.html)

mjona 18th September 2020 09:06 PM

Scott Wurcer is an engineer who designed high spec linear integrated circuits. He has mentioned parasitics - see Looking for a small signal NPN with no Quasi Saturation: MEASURED DATA.

The practical capacitance values end users get to work with can be found by looking up datasheets or SPICE .models for the device concerned. The relevant terms for capacitance in the latter are CJC and CJE.

You could have quantified your announcement with some information.

knutn 19th September 2020 10:27 AM

What is humongous nonparasitic interelectrode capacitances?

stanislav1957 19th September 2020 12:07 PM

Topic about the operation of an amplifier on a load with a large capacitive component in the absence of an RL filter ?

mjona 19th September 2020 06:54 PM

Quote:

Originally Posted by knutn (https://www.diyaudio.com/forums/solid-state/359704-stability-amplifier-capacitive-loading-post6346520.html#post6346520)
What is humongous nonparasitic interelectrode capacitances?

No comment.

duncan2 19th September 2020 07:36 PM

Take each word at a time -
Humongous -- large , supposed to be of American origin .
Parasitic an insect/organism/flea/intestinal worm / etc -- living off its host .
interelectrode --between electrodes or an electric chair customer .
Capacitance -- storage ability of your stomach or electrical energy .


Sounds like an old Western movie with the wagon fast talking barker selling fake medicine that "cures " baldness- headaches- gout-blindness-and every disease under the sun while beating his cane to attract attention in a small western town .



Of course the brave sheriff arrives and carts him off to jail ---and fines him.

duncan2 19th September 2020 08:16 PM

Found it- homongous

The word was first coined by Tommy Dean (TD) Stanley -Professor of Hendrix College-established 1876 --Conway-Arkansas.
Its near the Ozark mountains their website actually looks beautiful which in this day and age is saying something.


Hendrix College

N101N 20th September 2020 06:23 AM

Capacitance: the amount of electric charge - would be a more adequate definition. Unsurprisingly, the current handling capacity is directly reflected by the intrinsic capacitances.

knutn,
choosing the right transistor for that job is critical. You could try the KSA1381, but I personally only trust authentic manufacturing.
Although Hiraga selected the parts with great care, the 2SC1096 (NEC) is of the wrong type (high current handling capacity), my option would have been the 2SD758/2SB717 from the venerable Hitachi.

Also, keep in mind that the (input & output) load is the extremely complex product of inductive and capacitive reactance. In this and other respects, your software won`t get you anywhere.

mjona,
maybe you think that paying attention to details is not worth the hassle. Nevertheless, you still have a chance to build mediocre amplifiers.

Instead of audio amplifiers, people design oscillators and voltage regulators, not so seldom inspired by influential authors. It should stand to reason that amplifiers with instability issues cannot have good (high frequency) response.


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