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mhrackin
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Re: Meter Guts
mhrackin   8/22/2014 3:31:31 PM
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I suspect this (AC) ammeter also has a removable rectifier in it; the clue is the "dead zone" between 0 and 2A, where the voltage across the shunt is below the band-gap voltage of the rectifier bridge.  Looks to be actually 1.4 A, so assuming Si diodes, that tells me the shunt should be close to 1.0 ohms.  Isn't it amazing how I can do the "Sherlock Ohms" thing from this far away?  Thus my constaint complaint about the negelect of basic physics in today's EE curriculum.

Clive
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Re: New faceplates for analog meters
Clive"Max"Maxfield   8/22/2014 3:29:44 PM
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@DrQuine: The new text was on several small spot labels that covered the old text. If you have access to an old lettering guide and a good fine point permanent pen that might also work well for small captions.

I think this option would be very low down my list of solutions -- I want every aspect of my projects to make the observer gasp "Wow -- that is amazing -- let me buy you a beer!" LOL

DrQuine
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Re: New faceplates for analog meters
DrQuine   8/22/2014 3:24:54 PM
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@Max The Magnificent The new text was on several small spot labels that covered the old text. If you have access to an old lettering guide and a good fine point permanent pen that might also work well for small captions.

Max The Magnificent
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Re: Meter Guts
Max The Magnificent   8/22/2014 2:58:43 PM
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@mhrackin: Also, nearly all faceplates are symmetric; thus no need to scrape.  Just flip it over and paint!

Well, b##### me -- believe it or not, that had nerver struck me, and I'm starting the faceplate right in the ... well, face, actually :-)

Max The Magnificent
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Re: Meter Guts
Max The Magnificent   8/22/2014 2:57:08 PM
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@mhrackin: ...examining the photo of the disassembled meter, it has an internal shunt THAT CAN BE REMOVED. That would restore the basic movement range etc. so you can use it! 

HAPPY DANCE!!!

Max The Magnificent
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Re: Realistic
Max The Magnificent   8/22/2014 2:55:45 PM
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@Antedeluvian: ...or written with a typewriter with a rather grungy ribbon...

But where are we going to find a rather grungy ribbon at this time of the day LOL

Max The Magnificent
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Re: New faceplates for analog meters
Max The Magnificent   8/22/2014 2:54:34 PM
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@DrQuine: They were buying 0 - 20 ma gauges and then affixing new text on the meter faces for the application at hand.

Don;t keep me in suspense -- how was the new text presented? As sticky labels or as re-painted faces or...

 

antedeluvian
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Re: Meter Guts
antedeluvian   8/22/2014 2:45:52 PM
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mhrackin

(if you can find some India ink.....). 

I think I saw some in my drawer after I went rummaging after reading David Ashton's Slideshow: The Joy of Rotring

 

mhrackin
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Re: Meter Guts
mhrackin   8/22/2014 2:39:07 PM
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Also, nearly all faceplates are symmetric; thus no need to scrape.  Just flip it over and paint!  I've used that trick many times.  If you have an old drafting tool/ pen set, the compass is terrific for draing the scale arc (if you can find some India ink.....).  I have a couple of sets (including one older than I am).

mhrackin
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Re: Meter Guts
mhrackin   8/22/2014 2:35:24 PM
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PS: examining the photo of the disassembled meter, it has an internal shunt THAT CAN BE REMOVED. That would restore the basic movement range etc. so you can use it!  Same for "voltmeters" except the multiplier is often external; if it is internal, it's also easily removable.

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