Magnetics question

Try it! But I suspect not. It's a beam lead, probably all silicon and gold. Like these:

ftp://jjlarkin.lmi.net/BeamLeads.JPG

These are very hard to handle and mount. Solder will dissolve the beams. These are usually welded, maybe mountable with conductive epoxy. There's an old HP appnote on all that, probably inherited by Avago. I think you can pick them up with a toothpick dipped in aclohol or something like that.

Why do you want something this small? How about an SC79? You can solder that.

Beam lead schottkies can have capacitances around 0.05 pF. Packaged parts, like SC79s, are more like 0.2 pF. 50 ohms and 0.2 pF makes 10 picoseconds, which should be fast enough for most folk.

I like SMS7621-079 for a small, fast diode. You can sort of actually see it. There are three on here, in parallel, partially under the orange wire:

ftp://jjlarkin.lmi.net/BB_fast.JPG

Are you planning to make your own hybrids?

John

snipped-for-privacy@netzero.com schrieb:

Hello,

I guess the magbetic force is very, very small. So small that it would be difficult to measure the force. Remember that the head should magnetize only a very small area of the disk surface to enable the high storage density. The distance between head and disk surface is smaller than tiny dust particles.

Bye

Easier to just use a bit of soft iron wire and a permanent bar magnet. You can pulse a tiny bit of AC on a coil around the wire when you want the thing to drop.

I worked at Control Data Magnetic Peripherals Division back when disks were 14" diameter, and heads were about 1 cm square. A 300 MB disk pack had 10X disks. A typical flying height was about 50 millionths of an inch. The heads had from 7 to 9 turns. There were charts on the walls showing the relative size of a human hair, a dust particle, and a smoke particle. The dust particle relative to the flying height looked like the Rock of Gibraltar.

I wonder if they've got that flying height down, or if it's a physical limitation because of the characteristics of the boundary layer?

Thanks, Rich

It is held to an optimal space, and the head footprint and boundary layer define it. Oh, and the speed the platter surface goes by. Less inboard, and more outboard. Mostly the same, but a slight difference between inner and outer 'ride height'.