# Permanent Single M/Meter for DC Layouts



## wvgca (Jan 21, 2013)

It's nice to have some kind of indication on a layout for voltage supplied and current used ... There are many ways to do this, but this version uses ONE multi-meter, for a cost of around five dollars ...
Most meters are installed in pairs, one for voltage, and one for current, but I chose to use only one, the wiring I use is permanent, no switching wires or leads to change from voltage to current ., just turn the dial..

The cheap meter that I used only supports DC current, and is not suitable for AC layouts ....


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## Lemonhawk (Sep 24, 2013)

Is there any problem when switching from current to voltage? Or does the meter protect itself? Apparently the meter only has one shut that is always connected between common and and the amp port and not switched. Good use of an easy to find asset (free and Harbor Freight!)


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## wvgca (Jan 21, 2013)

Yes, the current shunt is always in circuit no matter where the dial is placed, or whether or not the meter is powered up ...
I do try and swing the dial so as not to go through the ohm or diode check selector positions.. I did a few times but the meter did not seem to be affected [so far anyways]


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## gunrunnerjohn (Nov 10, 2010)

Maybe it's just me, but it seems a lot of trouble to eliminate one meter. Also, the dual voltmeter and ammeter can be conveniently panel mounted for easy visibility.


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## wvgca (Jan 21, 2013)

on my first layout from ten years ago, I used this style because I didn't have physical room to mount two meters ..
In the image above, it's my three foot HO test circle and I didn't have two meters to spare at the time .. I somehow happen to keep driving over them with tractors 
The circuit show is just an alternative, and Yes, two seperate meters would be better in my opinion as well


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## gunrunnerjohn (Nov 10, 2010)

I think for a 3 foot circle, the multi-meter is sufficient.


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## gregc (Apr 25, 2015)

how often do you need to know track voltage or current? what kinds of things are you doing that made you do this?


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## wvgca (Jan 21, 2013)

For me, it's nice to know at what voltage a new [to me] loco will start up at, and current draw can sometimes give an indication of the general condition of a loco, and whether there may be any driveline issues ..
Yesterday I ran an old MDC boxcab, current was initially 0.35A, then it gradually came down to just under 0.3A after a couple of loops, which made me think it might be time to clean out the old grease in the reduction drive, and relube that gear set, plus lube the trucks as well ...


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## Shdwdrgn (Dec 23, 2014)

Hmm this reminds me, I had been thinking of checking what China has to offer for this sort of thing. I ran across this listing, and for that price (less than $3US) you could afford to permanently mount one on each power supply. Note that it does need a supply voltage of 4.5-30VDC to operate, but it measures 0-100VDC and 0-10A.

http://www.ebay.com/itm/DC-100V-10A...p-Dual-Digital-Volt-Meter-Gauge-/201607446866


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## wvgca (Jan 21, 2013)

Shdwdrgn .. 
I have a couple of these, the link you show is a bit nicer as it has two different colors..
the main reason that I went with the meter on my test track is simply that it stays put better , without having to put a hole in the table and mounting it permanently
However, for a permanently mounted unit for a DC layout, those meters would be a much more elegant solution, might have to angle them a bit though, for easier viewing


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## Shdwdrgn (Dec 23, 2014)

Oh I have no reservations against using what's on hand, but my multimeter requires me to swap jacks to measure amperage, and I figured in this day and age there ought to be a cheap digital readout that could give me both readings at once. From the descriptions, it looks like these will measure 0.01A increments, which is pretty nice. I'm just curious to see how much juice my locos pull on a test track, but once I start building my layout something like this might be nice to throw on each power supply for early warning against heavy draw. I went ahead and ordered a couple to play with until that time.


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