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gwrightoy

Volt meter details

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Hi , can anybody tell me if this volt meter that I have discovered is  of any use. I connected it up to a 12v car battery but nothing happened .The top scale I thought should be DC volts but the bottom scale I don't know( a little high for DC volts? There is also a small terminal below which says Fe and nfe. That's something to do with ferrous and non ferrous ? Any ideas thanks Graeme

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As it says use external resistor I suspect you may have damaged it . this style of galvanometer is supposed to have a  resistor in series with  it  you then connect the resistor and voltmeter across the voltage you want to measure.

The scale is a Dual scale as this would be a panel mount meter with a switch to change the size of the resistor in series with it .

More for test equipment than vehicles. The Fe refers to Iron in the core.

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Hi,

It's a 500uA meter so would need a resistor of around  30,000 Ohms (slightly less because of the meter resistance) to read 15V full scale. If you managed to connect it to a 12V battery you will have destroyed it if it was not already faulty. 
Note that this meter is radioactive. It has small dots of Radium luminised paint on the pointer and dial. These are the little brown blobs. They won't glow in the dark anymore but are still radioactive. It's not particuarly hazardous unless you open it up or sleep with it on your pillow.

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Good question. As far as I know there was no easy disposal route for Radium (it's 226Ra to be precise) in th UK. Other common radioactive materials in this sort of quantity can be disposed with regular rubbish, but NOT Radium. It emits gamma radiation and even this small amount might trigger a radiation detector as fitted to many waste disposal sites. 

If there is no chance that you would be considered a business (and thus charged) you could try asking your local environmental health department.

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