The "buck an ohm" group buy

[yldouright]

I recently came across some surplus Yageo 5W 1/2 wirewound resistors and the seller wants $100 for the lot of 200. Since I'm going to be matching them for my own amp, you'll be getting resistors that should be accurate to the milliohm. Are these any good and if so, is anyone interested in taking a piece of this?

[yldouright]

Just to update. I bought the whole lot and am in the process of matching them. They are 5W non-inductive wirewounds in a ceramic case. They fit into the hifi Zen Aleph-X boards and are the perfect source resistors for those 8 FET versions. They're also quite useful for you RC power supply builders who need a 20W tolerant scrubbing

[kilowattski]

With a low resistance value resistor it is best to use a multimeter with 4 wire ohms measurements if you have access to one so you can negate the resistance of the multimeter leads. Of course, if you are just matching the resistors without regard of it's absolute value it don't make a hill of beans.

[BassAwdyO]

How can wirewound resistors be non inductive?

[raidfibre]

I believe they are wound half in one direction and half the opposite direction so the magnetic fields cancel out.

[Coulomb]

Originally posted by raidfibre
I believe they are wound half in one direction and half the opposite direction so the magnetic fields cancel out.

That would not be so much a cancellation effect as a phase reversal effect. The winding pattern you refer to would be like to inductors in series, one with a left hand twist and one with a right hand twist. Cancellation requires two seperate coils with seperate twiist around a common core. They share the input and output leads so each coil is a seperate resistor, a non magnetic resistor is two resistors in parralel both are inductive thay just generate opposite fileds simultanously and cancel each other simultaneously. It would be impossible to have a coil that is non inductive, so make two inductive coils to cancel each other.

Regards

Anthony