Ian Iveson wrote:
> Ian Thompson-Bell wrote:
>
>> Ian Iveson wrote:
>>> Ian Thompson-Bell wrote
>>>
>>>> I have just been working through the math for shunt
>>>> derived shunt applied NFB around an amp and Ican't get
>>>> the expected result.
>>> Is that the same as voltage derived, current applied? I
>>> can never remember this stuff, sigh.
>>>
>> No, it's voltage derived, voltage applied. As a rule:
>>
>> Shunt = Voltage
>> Series = Current
>
>
> Thanks. Then how come your circuit employs "shunt derived"
> feedback?
>
Sorry, don't understand - the feedback network is fed from the output
voltage i.e. across or shunting the output. Is that what you mean?
> And perhaps you could answer the question you cut out from
> my post, considering I was good enough to answer yours:
>
My apologies, I must have missed it.
> "Your maths is correct or we're both wrong.
>
> "I don't know if it helps to see it as Ao/(1+ß.(1+Ao))
>
Yes, I had it as that to start with but changed it to 'show' the anomoly.
> "You haven't explained why you believe there is an anomaly.
> What led you to your erroneous expectation?"
>
I had expected *all* NFB forms (however derived or applied) to reduce to
Ao/(1+ß.Ao) but this one does not.
Cheers
ian
|
