# Volt meter modifications



## ianb26 (Dec 29, 2014)

Hi there,

Not sure if this is in the right forum. I'm currently building my own controller so I can test out my layout. I currently have a 0 - 20 Volt DC meter on the project and on testing the other day it worked OK, but on flicking the switch to reverse the locos the needle went off scale to the left I know there is way to centre scale the meter to read 10-0-10 but not sure how to do it. FWIW if I can find the way to do it I will be using a 0-30v meter (15-0-15). Turning the adjustment screw on front of the meter only moves the needle 1 - 2 volt on the scale.

Any help would be appreciated


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## fcwilt (Sep 27, 2013)

Not sure what you are doing but you may be able to put the meter before the reversing switch which solves the polarity problem.


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## DonR (Oct 18, 2012)

Your meter reacted to the reversed polarity when it went hard left.

The easy solution is to get one of the cheapo digital meters from
Harbor freight. On many weekends they give them away
free with a coupon. When the polarity changes it still reads the voltage
but shows a - (negative) icon.

Don


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## gregc (Apr 25, 2015)

fcwilt said:


> Not sure what you are doing but you may be able to put the meter before the reversing switch which solves the polarity problem.


nothing easier that this


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## ianb26 (Dec 29, 2014)

Thanks for your replies. I should have further detailed the background to my thread.
Many years ago (a lot to be exact!!!) I had a layout in a shed attached to the garage. Trying to keep costs down I used cheap roofing material (bad move!), consequently over the years the weather played a part in the roof deteriorating and affecting track and baseboard. When we moved house I salvaged the rolling stock and nothing else (another bad move  ). I had built my own controller and I had a centre scale 0 (15-0-15) volt meter. I've searched all the online electronic stores in Australia, but no one has these meters any more.  . Plenty in USA on ebay, but with the AU$ being low against the $US, the prices are a bit high, plus postage costs appear ridiculous.

So that is my dilemma. Also I was thinking of adding an ammeter as well. I have been told that opening the meter up and "playing around" with the hair spring I can achieve what I'm after, but I don't want to damage the meter beyond repair!!! Google searches on this information appears non-existent. That is why I posted here thinking I may have missed something.

Sorry for the long winded reply.

I await any further comments.


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## DonR (Oct 18, 2012)

No facts, but somehow I have the sense that a meter such as
you want will special electronics or special wiring. You'll know
more when you open it.

Don


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## Bwells (Mar 30, 2014)

Try this link, it has both volt meters and ammeters for dc

http://www.led-switch.com/Panel Meters.htm


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