Ways to *REALLY* erase a hard drive?

I read in sci.electronics.design that Barry Lennox wrote (in ) about 'Ways to *REALLY* erase a hard drive?', on Sat, 12 Feb 2005:

I made a magnetizer for model railway motor magnets that way about 50 years ago. Rectifier straight off the 240 V mains to a 20 uF cap through

10 kohms. Switch to connect the cap to a 'no-volt coil' from a motor starter - lots of turns. Custom-made magnetic circuit (the railway nerd provided that from his machine-shop).

Interesting that the switch current is initially zero and finally zero, so no arcing problems, but in between, about 2 A.

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Try a hammer and chisel. It works for me.

just put it all in a hole in the ground...

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Just a magnetic degausser works, but you need a reasonably powerful device. IIRC you require about 3500-4500 gauss for HDDs and DAT tapes, while most of the low-cost commercial devices are around 1000 gauss.

There's some info at

I used to use one that look a little like a microwave oven, and the manufacturers blurb stated it used a charged cap dumped through a coil. Never saw a schematic or got to look at it's guts however.

Barry Lennox

So would folding, spindling, or mutilating.

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  Keith

and WTF is it to widlarize something?

Are you a newbie or something? :) Do a web search for Bob Widlar.

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Michael A. Terrell
Central Florida

That's because you didn't click on the "groups" link. It takes you right to a post defining the term.

Are those the times before the first sector error?

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Reply in group, but if emailing add
2 more zeros and remove the obvious.

Those were the times before DOS scandisk running in a looping bat file stopped with an error.

I am surprised that I haven't seen a bunch of posts from folks who have tried this. Doesn't everybody has an old 100MB drive or two laying about?

Guy Macon

Guy Macon

I'm thinking maybe most of the other sectors were still readable.

Yeah, but I'm not sure of their reliability with the cover on, so it would be hard to compare. A new drive might last longer. OTOH, a new drive might be more sensitive. I don't know if I could do a meaningful test.

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Reply in group, but if emailing add
2 more zeros and remove the obvious.

It depends. If the platter was damaged, yes. If the head was filled with oxide, it might be all bad reads. If I ever do it again I will test for that.

You are correct, nothing! That's surprising.

Nevertheless to "Widlarize" something, is to take a hammer and beat the thing into little bits. Bob Pease has often written about it.

Barry Lennox.

I'd get a warranty replacement drive, and then get a cheap computer at a thrift store to open up. But that's me.

Torx, schmorx. The first step in doing "physical experiments" on a hard disk drive is using a Dremel (brand of handheld hobby motorized tool) with a cutoff wheel to cut head slots in the screws for a regular flat-blade screwdriver which then easily removes the screws. It's easy, works great, and it's not like you're going to have to put it together so that no one knows it's been taken apart.

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