I don't think there really has been a definition. It's just been assumed local means a shorter loop than global. But if you want to get some terminology better suited for different versions then you could say INTRAstage FB, for plate to plate (which is really plate to grid of the output through its coupling cap) and say INTERstage FB for FB going back to include one or more prior stages but not all stages, and then GFB for a system loop.
If you think 'I don't think there is ...' doesn't mean there isn't.
I am again surprised why people want to invent all kinds of terms that nobody else except they understand? Where does this obsessive behavior come from ??
From output to input is global. Everything else is local. What's so hard to understand about that?
It is abundantly clear if you want to see it, that the original title of this thread results from limited understanding of the term 'local feedback'. Local feedback does NOT mean that you return the feedback from output to some 'local' point.
The solution to limited understanding is NOT to invent other terms in an attempt to cover up the limited understanding. Rather, the solution is to read up and Get It.
Jan
I am again surprised why people want to invent all kinds of terms that nobody else except they understand? Where does this obsessive behavior come from ??
From output to input is global. Everything else is local. What's so hard to understand about that?
It is abundantly clear if you want to see it, that the original title of this thread results from limited understanding of the term 'local feedback'. Local feedback does NOT mean that you return the feedback from output to some 'local' point.
The solution to limited understanding is NOT to invent other terms in an attempt to cover up the limited understanding. Rather, the solution is to read up and Get It.
Jan
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Haha! Is that a trick to let me do your legwork? Will not work, if you are happy with what do or don't know, I'm not going to force you to your happiness. 😎
Jan
Jan
Here's a picture of a 3W 47k resistor used as a dropper for an LED. It dissipates 1.5W... It's also in a chassis that is basically an oven. As a rule, I build with the largest resistors practical now! Those 5k6 resistors are series/parallel connected for Pd of 12W with a circuit that needed 2.8W 🙂 I had them already though, so why not?
Since the burning resistor is just a dropper for an LED, I don't care at all that it's discoloured 🙂 If it explodes and takes the LED with it, J'men câlice 🙂
Attachments
Take a typical triode:
Use a Regulated grid power supply and a Regulated plate power supply.
Put the grid at -10V.
Put the plate at + 100V.
Put the cathode at 0 Volts
Wait for 1 day for the current to stabilize (are we there yet?).
Then measure the plate current (Ip1)
Put the grid at -10V.
Put the plate at +200V.
Put the cathode at 0 Volts.
Wait for 1 day for the current to stabilize (are we there yet?).
Measure the plate current (Ip2)
200V - 100V = 100V (the change in plate voltage).
Ip2 - Ip1 = Delta Ip (the change in plate current).
100V / Delta Ip = the plate resistance, rp.
Would you call that negative feedback?
After 1 day, the Miller Effect capacitive current is much less than KTB.
Use a Regulated grid power supply and a Regulated plate power supply.
Put the grid at -10V.
Put the plate at + 100V.
Put the cathode at 0 Volts
Wait for 1 day for the current to stabilize (are we there yet?).
Then measure the plate current (Ip1)
Put the grid at -10V.
Put the plate at +200V.
Put the cathode at 0 Volts.
Wait for 1 day for the current to stabilize (are we there yet?).
Measure the plate current (Ip2)
200V - 100V = 100V (the change in plate voltage).
Ip2 - Ip1 = Delta Ip (the change in plate current).
100V / Delta Ip = the plate resistance, rp.
Would you call that negative feedback?
After 1 day, the Miller Effect capacitive current is much less than KTB.
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I'm not technically astute enough to offer an opinion in the Local vs Global debate. Whatever the correct nomenclature is, I'm enjoying the amp. So thanks to all who helped.
I apologize if my reference to this as Local is hastening the end of civilization as we know it.
Ketje,
Creative!
You "quoted" me, but you changed my words.
I guess that you were saying the triode (rp) was acting just like a resistor.
And, most people will not argue that a resistor has negative feedback.
Thanks!
Creative!
You "quoted" me, but you changed my words.
I guess that you were saying the triode (rp) was acting just like a resistor.
And, most people will not argue that a resistor has negative feedback.
Thanks!
Isn't it true that a triode is effectively an electrically controlled resistance vs a current source like all others but SITs?
i can live with that....a triode is more like a Thevenin source with rp as internal resistance....
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