PC choke in a preamp ?

[Shoog]

Hi there,
I have just taken apart an old PC power supply, and to my surprise I found a full, quite large, EI core choke. It measure DC resistance of about 1.8R. I have no way of knowing its inductance.
My question is, will this work as an element in a Preamp power supply with a current draw of 30mA, or is it just going to be under to little load ??

Thanks

Shoog

 

[hacknet]

i think the inductance will be alittle low for any use at 50hz. you might want to build a simple jig to get a rough figure of the inductance under a 30ma dc load.

 

[analog_sa]

It will only work well in a heater's ps. Too little inductance.

 

[Shoog]

Thanks for that, its what I suspected.

Shoog

 

[kmtang]

Some Digital Meter employs testing of the Inductance and Capacitance as well. Most of the PC chokes are used for filtering of the RF interferences.

JOhnny

 

[Shoog]

This one is about 3" square and much bigger than most I have seen.
I have another small choke from an old SS amp which works at mains frequency if driven with about an amp, but did nothing with a 60mA load. I suspect that this one is similar, and if driven with about an amp it would probably work at mains frequencies. I don't know enough about the relationship between load and inductance to be certain though.

Shoog

 

[Shoog]

I also have a small (3"x4") from the small valve section of an old transmitter, this has a DC resistance of 68R which sounds a lot more promising. Still I am going to have to rethink the case as things just wont fit.

Shoog

 

[jackinnj]

this article describes a one opamp impedance measurement test set which uses the sound card. you can quickly and acurately the impedance of the choke using the setup Dr. Steber describes:

http://www.arrl.org/qex/2005/steber.pdf

the software is available in this zipped file:

http://www.arrl.org/qexfiles/LMSProg.zip