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Old 5th April 2008, 05:45 PM   #1
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Default panel meters

My searching skills are deserting me today. I though for sure I'd easily be able to find info here or on the web on the following.

I need to educate myself more about analog panel meters. These things cost way too much new. Lots of surplus stuff out there, usually doesn't have the range I want. I think the face plate can often be swapped out. Questions..

Fundamentally, what do these meters measure - current? - voltage?

Is there a basic standard full scale deflection value that most meters have? ie, Can I know if the surplus meter I'm considering purchasing will be convertible to what I want?

How can I determine the full scale deflection value of a meter?

Thanks for any help!
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Old 5th April 2008, 07:03 PM   #2
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Been there, done that. Here's the info you're looking for:

http://www.uoguelph.ca/~antoon/gadge...ts/shunts.html

http://www.wannatinker.com/MM.htm

http://www.qsl.net/kr6lp/meter2.html
http://www.qsl.net/kr6lp/meter.html

http://www.jacmusic.com/Yamamoto/html/meters/index.html

Enjoy,

-- josé k.
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Old 5th April 2008, 07:12 PM   #3
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Most all meter movements measure current. Even when the full scale is stated in volts, the movement is responding to a changing current.

There are several standard full scale current ratings that are very common. But nothing is written in stone and full scale ratings can be above or below these listed. 50uA, 100uA, 200uA, 1mA, 10mA, are the most common. But I've seen 5uA & 10uA. Bird Electronics uses a lot of 30uA movements. And some movements are specified in millivolts. The units are made to be used with shunts and will have an odd full scale current value.

The full scale value of a panel meter is often (but by no means always) written down low on the meter face or card as it's sometimes called. You can usually see it by looking at a very steep downward angle.

If a meter is unmarked as to it's FS rating, then you have to test it by applying voltage to it in series with a calibrated milliamp meter. Or one can use a precision resistor in series with it and do the math by measuring the voltage drop across the resistor with a high impedance voltmeter.

As far as interchanging scales, yes you can as long as you stick to the same make and model because it's a physical thing. Mixing brands and model sizes never works out because of the physical differences in size and mounting arangments.

All this applies to the standard moving coil types with D'arsonval (jeweled pivot) or taut-band suspensions. Other less popular types like iron vane and electrostatic movements have slightly different rules. Whether a given meter will serve your needs or not is something that can best be learned by experience.

Moving coil meters must be in balance to read correctly. To test balance, position the meter pointer vertical and note where it lies in relation to the scale 0. Then re-position the pointer horizontal and look for any movement off 0. Any imbalance must be corrected by moving the weights on the pointer's cross.

Victor
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Old 7th April 2008, 12:37 AM   #4
OzMikeH is offline OzMikeH  Australia
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Don;t move the weights unless the balance is grossly out.

Use a needle and a tiny dab of tacky shellac. it takes some time because you need to wait for the shellac to cure.

when setting the balance hold the meter with piointer up, down, left and right.

Vibrate it slightly to overcome the friction of the pivots. I find twirling the handle of a metal jewellers screwdriver avainst the casing is about right. You dont want so much vibration you bounce the pointer.
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Old 28th April 2008, 03:58 AM   #5
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That Yamamoto meter is just what I’m looking for but I can’t see myself spending $85 plus shipping per meter for my amp project.
Click the image to open in full size.

Has anyone have experience with one of these in the link below or ones that are similar?
http://www.allelectronics.com/cgi-bi...EL_METER_.html
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Old 28th April 2008, 06:07 AM   #6
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What about these analog 15 mA or 100 mA meters (scroll a little down the page). They are made in China but does it matter??? The price is absolutely reasonable ~ 10 $/each. Shipping should not be a major deal with these small items.

http://www.vt4c.com/shop/program/mai...&cat_id=60#403

Karsten
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Old 28th April 2008, 06:15 AM   #7
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$9.50 at Euphonia


Click the image to open in full size.
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Old 28th April 2008, 06:46 AM   #8
jormajj is offline jormajj  Finland
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Rod Elliot's article about panel meters:
http://sound.westhost.com/articles/meters.htm
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Old 28th April 2008, 07:32 AM   #9
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$9-$14 at Main Electronics in Vancouver. They mailorder

http://www.mainelectronics.com/panelmeter.htm
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Old 28th April 2008, 06:59 PM   #10
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I used this cool meter face software:

http://tonnesoftware.com/meter.html

It makes very nice looking meter faces.

I really like the "vintage" look meters, which are getting hard to find in the "normal" scales. But you can get good values on meters with odd scales. Most I've tried are either 50uA or 1mA movements.

Avoid sealed meters if you can - they are hard to open up to change the scale. It is possible, but difficult.

Pete
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