Do Wiggle Stick Meters Wear Out?

Older meters use jeweled movements and yes they probably do wear out. I've never seen one fail due to worn bearings. Usually it is from mechanical or electrical abuse.

We are all on the edge of our seats awaiting your report. I expect it will be a few years or decades though. :)

Higher quality meters may taut band suspensions which shouldn't wear out, at least not in the same way.

I suppose that if this will keep you from sleeping at night, you could install a switch to disable the meter. ;-)

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There are a lot of Weston meters still being used; mine was made in

1947 and still going strong.

How about the strength of the magnets? Old magnets may not maintain the same flux they started out with. Does that matter?

Isaac

In article , snipped-for-privacy@saul.cis.upenn.edu mentioned...

Sam, you're a card. Heh. I hope I'll be around for a few more.

I hada high school friend who had a Simpson taut band meter. It wasn't a 260, but a bigger meter where the meter movement itself was most of the case. I think the movement was 20 uA, it was really low current. Slow to move, but it had a mirror behind the needle.

Yeah, the range can be changed to higher curent or voltage where the stick doesn't wiggle at all as long as I keep my fingers off the V control. Funny, but these old PSes were built like tanks: they have an aluminum chassis inside an aluminum case. Then later HP made the

6214A and 6216A PSes and the cases are so fragile and brittle that they crumble when you try to take them apart. :-(

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Yes, it does matter. They are probably ALNICO magnest but used with a very low exciting field (the current through the coil) so they probably don't loose much of their strenght over time.

Good thought though.

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If it's actually a jewelled movement then there is likely some finite, but large, lifetime. If it's a taut-band movement then I'd expect the lifetime to be virtually infinite.

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

Consider that pocket watches use a very similar jeweled bearing on their balance wheel. The balance wheel rotates a few hundred degrees

5 times per second. Pocket watches are typically serviced every other year. They last for hundreds of years.... and yes, unlike a meter, they are oiled.

Your meter rotates a maximum of 60 degrees, typically. It would have to go zero to full scale 5 times per second to get even close to a pocket watch's bearing activity.

-Chuck Harris

Jim Adney wrote:

On Mon, 29 Dec 2003 05:30:49 GMT, Isaac Wingfield Gave us:

Unless they were heated or affected by a demagnitizer operating nearby... why would they?

On Mon, 29 Dec 2003 20:00:27 -0600, Jim Adney Gave us:

The difference between d'arsonval and taut band is the actuation of the needle, not the support bearing(s). Any mechanical meter movement that I know of has jeweled bearings, taut band or otherwise

D'arsonval utilizes magnetism, and taut band utilizes thermal expansion constants. The taut band is more accurate as it is directly attached to the needle. Magnetism is a bit more spongy, and therefore can exhibit error prone operation, with less linearity through its range. The taut band is repeatable through years of service (with calibration), and being directly attached to the needle, has near zero error through it's range, and a higher degree of linearity precision.

What exactly does using jewels mean? Obviously they use some sort of diamond or other "rock", but where and how? I never understood this ????

Thanks George

In article , snipped-for-privacy@erols.com mentioned...

Hey, thanks, I never thought about comparing the meter movement to a balance wheel in a clock/watch. But then ever since the late '60s I've been using watches that don't have a balance wheel. ;-)

I found a digital watch movement out on the street the other day. Bit rusted from the rain. I'll have to take the batt out and see if it will still work.

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In article , snipped-for-privacy@myfarm.com mentioned...

Sapphire or ruby? I forget. Here's a FAQ I found:

Skip down to the paragraph 4th from the bottom.

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My email address is whitelisted. *All* email sent to it goes directly to the trash unless you add NOSPAM in the Subject: line with other stuff. alondra101 hotmail.com Don't be ripped off by the big book dealers. Go to the URL that will give you a choice and save you money(up to half). You'll be glad you did! Just when you thought you had all this figured out, the gov't changed it:

In article , Watson A.Name - "Watt Sun, Dark Remover" mentioned...

HAH! ROTFL! Read the second from the bottom paragraph! Those Swiss elves don't know the diff between lubricate and duplicate! :-)

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That is incorrect!

The taut-band is a frictionless suspension system for the coil in the meter.

The biggest advantage of a taut-band suspension over a jeweled bearing suspension is this lack of friction.... You can make a more sensitive meter movement with the taut-band system.

Do a google search on "taut band meter" You will find pictures and descriptions-a-plenty.

-Chuck Harris

The shaft on which the meter coil is mounted has points at either end that rotate within a conical cavity in ruby or other similar hard material.

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No. It specifically deals with the bearings. Jeweled bearings have a steel shaft pointed at both ends rotating within a concave cavity in a ruby or other similar hard bearing material.

A taut band movement suspends the coil and needle on a very thing tensioned steel band which both provides the electrical connections and restoring force. There is no static friction with such a device.

These are both D'Arsonval - coil in magnetif field - movements.

There are also other types of meters but the references in this thread all refer to these types.

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On Tue, 30 Dec 2003 03:06:31 -0600, snipped-for-privacy@myfarm.com Gave us:

When one has a shaft that needs to be able to turn very freely, and said shaft is so small that normal bearing of the type used on bigger shafts wont work, a small cup shaped bearing, made from a hard crystalline material has a long life, high precision, and the pin ends of the shaft do not have a high degree of friction on them.

A shaft placed on a metal hole would wear, and wobble badly after a short period of action, and would also likely bind in operation.

Jeweled bearings on small shafts like instrumentation or watches and clocks makes for years of dependable maintenance free service for the shaft.

A jeweled bearing can last hundreds of years. The only thing that will or can wear is the shaft pin end itself, as the bearing is of a much harder media.

On 30 Dec 2003 08:22:55 -0500, Sam Goldwasser Gave us:

I know what a jeweled bearing is.

On Tue, 30 Dec 2003 08:16:02 -0500, Chuck Harris Gave us:

Yes. Thank you. I was taught that they were a different actuation method than D'Arsonval. I didn't realize that they were both d'arsonval, but that the taut band was a suspension system. I thought it was the actuation method.