AFAIK LEDs were produced with plated ferro leads since they were invented. I recall my first LEDs that were demonstrated in a Tandy store. Needless to say not many knew the exact series resistor story back then (worse is that many do not know today 😀). Of course I destroyed one immediately and noticed to my dismay (audio dude!) that it had ferro lead wires. These were silver plated or the like as they became black/dark after a while. Many ICs of that time had the same materials for the pins. These were not that good for side cutters too.
LEDs were supposed to give light as goal in life and consumed around 20 mA at birth so copper would have been an expensive choice. Todays LEDs glow bright with only a few mA so the choice for copper is even less likely.
LEDs were supposed to give light as goal in life and consumed around 20 mA at birth so copper would have been an expensive choice. Todays LEDs glow bright with only a few mA so the choice for copper is even less likely.
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Lo and behold! I throw away too old parts but for some reason I keep the LEDs so I went through my stock with a magnet and found very old (around 40 years) unused red 5 mm LEDs with ... non ferro lead wires... Certainly 99% of what I have is ferro (and 100% of recent LEDs) but a few aren't so they exist(ed). These old red LEDs need more current and have a darker/deeper red color compared to modern cheap LEDs.
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Well I have heard different comments on that but thank you. BTW if you want those new unused classic LEDs you can have them. They may be non ferro but maybe they are the most noisy LEDs on this planet 🙂
No thank you, i am alright, but your offer goes straight to my heart. I guess I will use the avago hlpm6000 like everyone.
Thank you. If I find a modern led (which is highly unlikely maybe some smd or medical stuff) I will update this post.
Thank you. If I find a modern led (which is highly unlikely maybe some smd or medical stuff) I will update this post.
Why is it important whether they are magnetic or not? BTW I like components with magnetic leads because when I drop them on the floor I just hover around with a magnet and I can collect a lot of long lost parts...
If you ask that question you could also try out coupling caps with ferro versus non ferro lead wires and discover what you like best. Next level understanding would be to think if you would like PCB tracks to be iron or steel instead of copper. Iron wire wound toroids, Iron/steel contact source switches. Imagine a moist sea side environment with that too.
And ... the caps?! Did you ever try that out?
It is not just about resistance. It is about price. Even LAN cables are available in copper clad iron versions (terrible garbage).
It is not just about resistance. It is about price. Even LAN cables are available in copper clad iron versions (terrible garbage).
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To be honest I never tried copper vs iron lead capacitors. Issue is I don't have the same type in both versions, so it would be difficult to compare. And most other components (incl. transistors, tubes) have iron leads, so it is difficult to go iron-free. But I believe you if you say there is sonic difference, only I have more important things to solve first.
It is practically too late to do so now. Many of us did it when electrolytic capacitors started to be produced with ferro lead wires. ALL electrolytic caps, regardless of brand/series, were once produced with tinned copper lead wires. One of the more known more recent examples is Panasonic FC that used to have non ferro (please note I don't write "copper") lead wires but were changed to ferro. Today it is indeed difficult to go iron-free.
Anecdote: a few months ago I received an old class A amplifier and it needed new caps and rewiring. I thought this was THE chance to use that spool with ultra nice teflon silver plated cable I kept for such devices. I listened but it was not that OK. Then it turned out that the cables are plated iron cables both the wire and the shielding. They stick perfectly to a magnet. Bummer.
Anecdote: a few months ago I received an old class A amplifier and it needed new caps and rewiring. I thought this was THE chance to use that spool with ultra nice teflon silver plated cable I kept for such devices. I listened but it was not that OK. Then it turned out that the cables are plated iron cables both the wire and the shielding. They stick perfectly to a magnet. Bummer.
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Copper, I don't think so. Maybe some very high power types that need to dissipate large amounts of heat, but that's not sure; you will need to do your own homework about that.
There might be non-magnetic types though, because they could be required in the vicinity of MRI machines, for signalling, lighting, etc. Expect a substantial cost premium.
Normally, when a conductor is embedded in glass, polymer, or similar, Kovar is used because it is a good match for the thermal expansion, has a good machinability and is not expensive, unlike platinum.
Kovar is used everywhere, in semiconductors, LEds, vacuum tubes, etc, but it is definitely magnetic (and it is not a very good conductor)
Copper, I do think so as I have a few here. Just cut off a small piece of the lead wire and it is copper.
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SMD, surface-mount, parts, you can use your own leads.
Some high frequency coax cables (for cable TV) have a copper clad, steel center conductor. They seem to work just fine.
The extra inductance of ferromagnetic leads can be an issue at large currents and low impedances when the inductive behaviour can stray into non-linear regions and be a significant impedance compared to the resistance, but for signal level currents this isn't the case - do the math! This is why a steel terminal post for a speaker wire carry 10Arms has definitely distortion issues, but a 1k resistor with steel leads carrying 3mA does not.
Here's the maths:
assume relative permeability of 1000 for 3cm 0.6mm steel component lead - online calculator makes that 1.5µH, the resistance is about 50mOhm.
So at 20kHz the inductive reactance is 20000 * 2pi * 1.5x10^-6 = 0.19 ohm (ie 0.02% of the total impedance of a 1k resistor).
At 3mA the magnetic flux density at the wire's surface would be 2mT. Iron's magnetic hysteresis sets in more like 1T, so its going to
be pretty linear at these current levels. What's more any non-linearity is diluted by the fact the inductive impedance is 0.02% of the
total impedance.
So basically no need to worry with standard line level signals and impedances.
The speaker terminal though, lets say 4mm diameter, 2cm long, inductance around 1µH (ie 0.125 ohm), flux density about 1T at the surface (very significant for distortion, well into the hysteresis curve).
So significant distortion forms about 10A x 0.125 ohms = 1.25A of the signal (ie 12% of the signal). If the hysteresis distortion was say 5%, that would be 0.4% overall THD. Of course the effect is lower at lower frequencies.
Here's the maths:
assume relative permeability of 1000 for 3cm 0.6mm steel component lead - online calculator makes that 1.5µH, the resistance is about 50mOhm.
So at 20kHz the inductive reactance is 20000 * 2pi * 1.5x10^-6 = 0.19 ohm (ie 0.02% of the total impedance of a 1k resistor).
At 3mA the magnetic flux density at the wire's surface would be 2mT. Iron's magnetic hysteresis sets in more like 1T, so its going to
be pretty linear at these current levels. What's more any non-linearity is diluted by the fact the inductive impedance is 0.02% of the
total impedance.
So basically no need to worry with standard line level signals and impedances.
The speaker terminal though, lets say 4mm diameter, 2cm long, inductance around 1µH (ie 0.125 ohm), flux density about 1T at the surface (very significant for distortion, well into the hysteresis curve).
So significant distortion forms about 10A x 0.125 ohms = 1.25A of the signal (ie 12% of the signal). If the hysteresis distortion was say 5%, that would be 0.4% overall THD. Of course the effect is lower at lower frequencies.
Skin effect makes it work as it should. That is different from audio low frequency use. High power RF is sometimes connected with hollow conductors.
Well at 100MHz the skin depth of copper is around 1 micron, so this might be perfectly fine if the plating is thick enough and its Gbit rates. Ethernet in particular has limited low frequency content due to the magnetics (signal transformers) used at either end. But if the plating isn't thick enough it will perform poorly -