Panasonic FC caps have magnetic leads

[Bricolo]

I just discovered this when I put one near a screwdriver.

Is this normal? I've always read that magnetic leads were bad, but in the other hand, everyone here seems to like FC caps

 

[2 picoDumbs]

Probably 16 years too late, but this is not normal.

All my Panasonic FC caps have non-magnetic copper leads.

 

[escksu]

I just discovered this when I put one near a screwdriver.

Is this normal? I've always read that magnetic leads were bad, but in the other hand, everyone here seems to like FC caps

Hmm... shouldn't because the leads are supposed to be tinned copper. I am thinking maybe there is charge in the capacitor so thats why it reacted to a magnetised screw driver?

 

[2 picoDumbs]

Or he got fake ones with iron leads.
Many capacitors have iron leads.

 

[lcsaszar]

I am thinking maybe there is charge in the capacitor so thats why it reacted to a magnetised screw driver?

 

[rayma]

Hmm... shouldn't because the leads are supposed to be tinned copper.
I am thinking maybe there is charge in the capacitor so thats why it reacted
to a magnetised screw driver?

If you short the leads together, you'll see that the leads are still magnetic.
Static charge does not create a magnetic field, only an electric field.

 

[escksu]

If you short the leads together, you'll see that the leads are still magnetic.
Static charge does not create a magnetic field, only an electric field.

Oh ok.... Then its likely the leads are made of iron or some ferrous metal.

Btw, a charged capacitor does have a small induced magnetic field.

 

[rayma]

Only moving charge can create a magnetic field, not static charge.

 

[afa]

Why are magnetic leads bad?

 

[rayma]

Hysteresis distortion. Hook up some steel wire to your speakers and see.

 

[afa]

Thanks, but who would use steel wire for speakers?

 

[rayma]

Why not, if there's no distortion? Steel is cheap, though higher resistance.

 

[Circlotron]

Would be interesting to wind a voice coil with steel wire. It might encourage the magnetic flux to stay in the gap and go through the coil. Less fringing maybe?

 

[rayma]

Probably steel would be too heavy for use on a voice coil.

 

[escksu]

Only moving charge can create a magnetic field, not static charge.

Yes, but there is no such thing as perfect dielectric. All capacitors has a small leakage current.

 

[2 picoDumbs]

Magnetic hum fields are also likely to be picked up and may end up on your audio signal.

 

[2 picoDumbs]

Yes, but there is no such thing as perfect dielectric. All capacitors has a small leakage current.

Does it even leak when the cap is open circuit?

 

[escksu]

Does it even leak when the cap is open circuit?

Yes, but the leakage very very small. I saw the datasheet and its around 3uA. This is also why the charge in a capacitor is not indefinite. The main leakage is due to the dieletric (the insulation) used between the +ve and -ve plates. IF you have a perfect dielectric, no electrons can migrate over. But in reality, this is not possible.

 

[thimios]

Unfortunately, now days steel is present everywhere.
R.F cables, L.F cables, electrical cables.... everywhere!
Cooper is expensive so it is time for low quality,bad parts.

 

[escksu]

Probably steel would be too heavy for use on a voice coil.

Weight not an issue because copper is even heavier. Copper is denser compared to steel. I believe the main issue is resistance. Due to higher resistance the coil heats up easily. That means quite alot of power goes into heat instead of moving the cones.