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My new 1954 Kilovolt Meter

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MikeT1982

Tue Apr 24 2007, 08:27AM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
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Posts: 119

Oh boy....well I was looking for a DC Kilovolt meter and was tempted to build one like you guys said out of a milliamp meter....that was untill I found a "New Burlington 5 Kilovolt DC" analog meter on ebay. Well it arrived today and is new, no marks or signs of use and I love the look of it, BUT by far I couldnt help but laugh when I saw on the box it was dated manufactured in 10/1954!!!!!!!!!!!!! This is the most extreme example of New OLDDDDD Stock I have ever seen!!! I am darn glad I won it for only $6.00.

Well here goes, it says it needs a resistor but doesn't specify. It reads 0-5 Kilovolts and at the bottom it says in small writing " F.S. = 1mA" I am guessing this means full scale or full swing equals 1 milliamp. Anyways any suggestions on how to choose its needed resistor would be greatly appreciated.

Heck here's a picture of it, I'll attach it -

EDIT!!! I just went back to my old thread and reread it carefully, someone explained it to me, so I used the Ohm's law equation and found that if I am correct and I am understanding the "F.S. =1 mA" thing on the meter to mean what I think I need a 5,000,000 Ohm or 5 Megaohm resistor. However it was mentioned in my post enquiring about using mA meters, that I should connect the resistor to the high voltage side and the meter to the low voltage side....please explain further....can't I just connect one lead from the meter to my cap bank's NEGATIVE terminal and the other meter lead to the resistor and the resistors remaining lead to my cap bank's positive terminal?

Using the other euqtion it also looks like I will need a minimum of a 5 watt resistor as 5kV@1mA = 5 watts.

HV Enthusiast

Tue Apr 24 2007, 01:19PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Yes. Its really not a kilovolt meter. Its just a standard DC meter with a label that reads KVs. As you said, you'll need a resistive divider network to scale it appropriately.

ragnar

Tue Apr 24 2007, 01:36PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
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EastVoltResearch wrote ...

Yes. Its really not a kilovolt meter. Its just a standard DC meter with a label that reads KVs. As you said, you'll need a resistive divider network to scale it appropriately.

OK, not "really" a kilovolt meter... but it's the only meter you'll find that LOOKS like one. (i.e. round fascia, nice pointy needle, dangerous looking calibrations)

It looks beaut. =)

Hazmatt_(The Underdog)

Tue Apr 24 2007, 08:20PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Here are a couple more examples of current meters that look like volt meters. They do it this way because you wouldn't want several kV on a panel mounted meter, its just too dangerous. Its also important to use a current meter to convert voltage if you have a case where your circuit goes from open to short.

The GE meter is 1mA full scale, and the Weston is 200uA full scale.

If you have some precision resistors lying around you could make a really nice analog volt meter with a neat vintage look.

MikeT1982

Wed Apr 25 2007, 12:52AM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
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Posts: 119

Thanks guys. So do I just have to wire the resistor in series with the meter, or must I run the cap bank being measured's power leads to a series of 2 different ohm rating resistors and tap hot and ground across one using ohms law to get the lowest voltage ...or something along that way...LOL.

ShawnLG

Wed Apr 25 2007, 03:34AM

Registered Member #286 Joined: Mon Mar 06 2006, 04:52AM
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1ma meter would load some measurements too much and cause a false reading. A flyback can only put out around 1ma of current. Meashureing that would sink its output voltage down. You would be better off finding a meter that is rated 50 ua at full scale.

MikeT1982

Wed Apr 25 2007, 04:01AM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
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What I am actually measuring is a 244 Microfarad Cap bank charged to about 5,000 volts DC from a 120mA transformer, would the 1mA draw really still affect this?

Simon

Wed Apr 25 2007, 06:22AM

Registered Member #32 Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549

While it is charging at much more than 1mA, no, there won't be much effect.

When it is off the charger, 1mA will discharge it at a rate of I/C=4V/s. (Bearing in mind that that 1mA is the FS current.)

If you really want to model that properly, take the total meter resistance and work out the time constant RC. That's how long it'll take to discharge to .36 of the original.

thedatastream

Wed Apr 25 2007, 06:41AM

Registered Member #505 Joined: Sun Nov 19 2006, 06:42PM
Location: Yorkshire!
Posts: 329

MikeT1982 wrote ...
...However it was mentioned in my post enquiring about using mA meters, that I should connect the resistor to the high voltage side and the meter to the low voltage side....please explain further....can't I just connect one lead from the meter to my cap bank's NEGATIVE terminal and the other meter lead to the resistor and the resistors remaining lead to my cap bank's positive terminal?...

Connect like this

Cap bank +ve ---> series resistor ---> meter ---> Cap bank -ve

Provided your cap bank -ve is connected to ground, there will be less voltage difference between the meter and ground. PRobably doesn't matter that muchbut if it's an old meter and insulation has degraded then touching the meter that has one input floating at a anything up to 1kV who knows what could happen.

MikeT1982

Wed Apr 25 2007, 06:52AM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
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Posts: 119

Thanks a ton man. Out of curiosity I am going to try to mess with milliamps and milliamps on my Fluke to see how a 2006 fluke compares to a 1954 analog. I have confidence in the old beast, I've got an ancient oldschool beam style torque wrench given to me by my uncle I use on my car that was within a few pounds of a newly calibrated Fancy clicker Norbar (really high end) torque wrench I borrowed!!

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