Distinguishing non-inductive res. vs. inductive?

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James Romeyn

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Distinguishing non-inductive res. vs. inductive?
« on: 14 Jul 2014, 06:21 pm »


Vendor describes these as non-inductive.  How does one confirm whether inductive or non-inductive? 

Tx!

*Scotty*

Re: Distinguishing non-inductive res. vs. inductive?
« Reply #1 on: 14 Jul 2014, 07:10 pm »
Jim, number manufacturers of non-inductive resistors is a pretty short list,what brand are they. If the resistors you show in your post are carbon film or carbon comp resistors they would also be non-inductive.
Scotty

James Romeyn

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Re: Distinguishing non-inductive res. vs. inductive?
« Reply #2 on: 14 Jul 2014, 07:16 pm »
http://www.ebay.com/itm/200-Pieces-150-Ohm-1-Watt-Noninductive-Metal-Film-Oxide-Resistors-/311006286145

Hi Scotty,
Thanks for chiming in!

I don't see brand in the link.

Seller has good rating, for what that's worth...

I was surprised to find the Mills non-inductive power resistors are 1%, tighter tolerance than I would have expected. 
 

*Scotty*

Re: Distinguishing non-inductive res. vs. inductive?
« Reply #3 on: 14 Jul 2014, 10:59 pm »
A metal film resister has a spiral of metal film deposited on an underlying substrate which equals a miniature coil with a certain amount of inductance. The larger the resistors value the more inductance you have.
 I don't know that I would characterize these resistors as having no inductive value to go along with the resistance that is present but because the value is relatively small the inductance will also be low.
 Whether these resistors will work for you depends on your circuit application. If you actually need something with almost zero inductance you may need something like a Mills resistor. The inductance due to the leads that the resistor is terminated with can also become a critical factor in certain situations.
Scotty

James Romeyn

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Re: Distinguishing non-inductive res. vs. inductive?
« Reply #4 on: 15 Jul 2014, 12:04 am »
Thank you sir!

I make speaker to line level decreasing circuit: 15 Ohm/10 Watt load resistor (wired parallel immediately after the source amp binding posts) followed by a divider network in front of the load input, 8k/1 Watt series followed by 1.5k/1 Watt parallel. 

I would parallel ten of these 150 Ohm/2 Watt resistors for the 15 Ohm/10 Watt value.  Unknown whether non-inductive is audibly better but it can't hurt.   

For the divider network resistors I purchased Vishay S102 .6 Watt, two each parallel = 1.2 Watt.

Even using a cheap 9.5k potentiometer for the divider network and cheap ceramic resistor for the load, the speaker outputs sound better than the RCA pre outs while driving two main amps (47k each input) and one sub amp (12k)...total load resistance 8k Ohm.