There is one type of excess noise that's real and measurable:
> temperature fluctuations changing resistance in a voltage divider,
> converting DC to super-low-frequency noise.
Right, otherwise known as thermoelectric effect. You can make a pretty good people detector using that.
"John Larkin About F****it TROLL "
They're all about the same.** A blind man's opinion of the view.
All resistors have identical Johnson noise.** Yawn ............
If there's voltage across them, some may have "excess noise",** So the trolling, autistic fool has no experience to draw from.
> which should in theory be very small for metal film resistors.
I've** A blind man's opinion of the view.
> tried to measure the excess noise of various expensive (thin film) and
> dirt-cheap (cermet and carbon film) resistors, without success; they
> all seem the same.
It all looks dark to him.
....... Phil
Thermoelectrics and, when the voltages across dividers is high, just the temperature coefficient of the resistors themselves. Much worse if the resistors are dissipating any amount of power: in that case, micro air currents modulate the resistor cooling hence temperature a lot more than if the resistor is passively following air temperature.
A similar effect is close-in sideband noise in crystal oscillators and especially TCXO's, where putting a cover over the oscillator is as good as spending 10 times the money on a better part.
I wonder how many measurements of resistor "excess noise" are confounded by these other effects. A bunch, I'd bet. That would help explain why the measurements seem to be so inconsistant.
John
I've done experiments to measure excess noise on a variety of resistors, and never resolved any noise-versus-bias voltage effects with a measurement floor close to Johnson. What have you done?
John
"John Larkin F****ng MORON "
** A blind man's opinion of the view. ** So the trolling, autistic fool has no experience to draw from. ** A blind man's opinion of the view.It all looks dark to him.
....... Phil
You do. Quite often.
-- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85.
Michael A. Terrell Central Florida
Audio amateurs always have strong opinions.
John
He doesn't have time for a life. It takes all his time to be a blithering idiot, feeding all those cats, and doing unspeakable things to toasters, and other small appliances.
"Winfield"
** Go get stuffed - you ASININE vile, old fart....... Phil
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