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.