Magnetize/De-magnetize

make an AC magnet (for example, a tape head demagnetizer will do, or a few hundered turns of #24 wire around a spool of your choice) turn magnet on, put screw driver near magnet and slowly move it away until it's about 24 (or more) inches away, then turn off magnet.

If you have a soldering gun, it is a great demagnetizer. Pull the trigger on the gun, run the screwdriver through the loop formed by the tip a couple times and get the screwdriver well away from the gun before releasing the trigger. Back when I was in the TV repair business (almost in a previous life, it seems...) I carried a loudspeaker magnet with me and I'd use it to magnetize a screwdriver when I needed it and would then demagnetize it with the soldering gun when I was done.

Jerry

Gee, a really low tech method I have been using for the last 30 years is to

1.Salvage a good strong magnet from a junky car speaker - newer ferrite type "donut" one are best..

1. To magnetize - stroke along screwdriver shaft
2. To demagnetize - whack screwdriver shaft sharply on edge on workbench.

To pick up things that are non magnetic, use a small dab of beeswax on the tip. (or BluTac if you want to be modern)

Next lesson to follow - uses for The Wheel.....

Andrew VK3BFA.

I generally find that a good solid tap on a metallic object such as a vice will weaken it enough to solve the problem.

A Weller or Wen soldering gun. Pass the driver through and slowely withdraw. ...lew...

Ok, I have the same problem from time to time... how do these things get magnetized in a shop with no magnets around???

LLB

Beat on any hunk of iron (and hardened steel is better) with it oriented N/S, and it will become weakly magnetized. Even little shocks from slipping off a screw head, or tapping the end will do it.

De-magnetize any long/thin tool with a degaussing coil.

LLoyd

I've often wondered why that works. I'm guessing the shock shakes the magnetic domains inside it loose and the earth's field lines em up before they settle down.

Izzat it?

Jeff

But you have to pay attention that the axis of the part to be de-magnetized is *not* along the magnetic field (north-south; in some 30°-ish angle to ground, depending on where you live).

Nick

Aah, the TV repair business. Jerry, as a kid I always wanted to do TV repair. Had the HeathKit VTVM, Signal Generator and Tube Tester by the time I was 13 years old. I was crappy at it, but I loved it. Would go to the Salvation Army and buy old Emerson TV's for $ 2 each. By swapping parts I could always make 1 out of two. Probably more like 3 out of 5. Would sell the sets for approximately $15-$20. Big money in those days of $1.56 minimum wage. Before my tube tester I remember spending hours at the drug store using their tester. Moved around to different stores so I wouldn't abuse the privilege. BTW, it seems that in those days (1950's) the TV repair guy was the busiest person in town. Aah, those were the days!! Unless you, at least once, wrapped your hand around a flyback transformer, you don't know what we are talking about. Thanks for reminding me.

Ivan Vegvary

That's the most common explanation. You can make a surprisingly strong magnet that way. A well-beaten piece of steel starts to work harden, and as it hardens, it retains more magnetism. A few licks on a well-hardened screwdriver in the right orientation will make it strong enough to retain screws fairly effectively.

I use a VCR tape degausser to "erase" my tools. You have to remember to work the tool away to a distance of more than a foot from the coil while it's on to be completely effective. Bench-mounted hollow-core degaussers are standard items for electronic and tiny machine (watches, etc) repair benches. I think it's Weller who makes a combination magnetizer/degausser for screwdrivers.

LLoyd

My dad and I invested in a CRT tester/rejuvinator. We made a bunch of change just collecting "dead-crt" sets, and punching another 6-months of life into the cathode.

LLoyd

Years ago I ended up with an old TV degaussing coil much like the one depicted here:

It works great on tools, and is big enough to easily take care of larger items like the vise and anvil.

As others have mentioned, turn it on at arms length, move it in and wave it around, then away again before releasing the switch.

A friend tells me these things can play hell with wrist watch stepper motors... and I don't doubt it. I keep my watch away when I'm using the coil.

Erik

On Tue, 12 Jun 2007 09:08:01 -0500, with neither quill nor qualm, "LLBrown" quickly quoth:

Unauthorized screwdriver arc welding on HOT outlet boxes? DAMHIKT

- Metaphors Be With You -

Lloyd, I remember those being around. Bunch of connectors for the different CRTs. How did they work? Just high voltage to burn off some surface electrons?

Thanks, Ivan

To rejuvinate a tube, you overheated the cathode, then drew an unusually high current from the cathode to the grids (using them together as an ersatz anode in the absence of a high-voltage supply). It was enough to ablate the emitter surface of the cathode, and expose new material.

You could usually get another six-to-twelve months out of a rejuvinated tube. The unit we had could also do capacitor-discharge re-welding of broken cathode and grid tab-welds.

LLoyd

While we are at it: Has anybody got plans for a demagnetizing table? The ones you most often find near surface grinders? Basically, they should be a transformer with an (cut) open core and some means that is reducing the current through the x-former to zero within some time. Right?

So, anybody, please?

Nick

You can accomplish the same thing as "ringing down" the current by simply waving the article around - first ON the electromagnet, then slowly moving it around further and further away.

Most inexpensive step-down transformers of the E/I core variety can withstand being powered for a minute or two with the core crippled.

Just disassemble (or cut) the "I" section off, and use it with only a little trepidation on the first power-up. Normally, you'll find they're good for about 30 seconds on/2 minutes off.

LLoyd

I have an old 120 volt xformer with EI laminations from which I removed the I part, with an old line cord attached to it.

It does the demag jobs fine for me.

Jeff