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Retro Ameters and Voltmeters

 

Allan, greetings from the temporarily frozen High Plains. 19 degrees, freezing fog and light snow. Crackling fire and glass of wine evening! Anyway, if I hooked up a vintage voltmeter or ammeter across the leads for a power district, what would I expect for a reading? I have used a regular VOM in the past, and although it is probably in inaccurate reading, I have used the reading as a reference between and among power districts. This is all just for fun. Jerry Michels
 

Hi Jerry,
?
To anyone who wants to try this:
?
1.? Do NOT hook up any amp meter across any kind of power source whether that be a power supply, battery, booster output or across your track.? If you are lucky, all you will do is blow a fuse.? Some amp meters have some hard to find fuses or no fuse at all.? Amp meters must ALWAYS be placed in series with the output of one of the leads from your power source.
?
2.? If you hook up an analog meter (across the power source for a volt meter and in series for an amp meter), be sure to use an AC meter.? A DC meter will read zero.? An AC meter will read low.
?
I have several RRampmeters.? For those that don't think they can afford one, a regular digital multimeter can be used if you don't care about the exact reading.? Quite often, a relative reading is adequate.? For example, say you place your meter across your booster and it reads 6.7V.? That becomes your reference.? If you are using electronic circuit breakers or block detectors, measure at their output and that becomes your reference.? Now if you measure along your track and you get close to 6.7V, you are good.? Sometimes, you just want to know if you have voltage or not.? So while I have RRampmeters, I often just reach for the nearest handy digital multimeter.
?
Allan Gartner
Wiring for DCC
 

Thank you Allan for the good advice. Although I am by far no electronic person, but when doing anything on my layout that requires a power reading I use an old standby Sears multi-meter.
But not sure if I am doing this correctly so here goes. If I want to measure volts in track power I use my multi meter. I set the selector knob on VAC and attache the probe to the tracks. I get 14VAC on a Digitrax Super Chief DSC100.
I am using a multi adjustable power supply set on 16 volts of power to my command station. My meter doesn't? measure amps AC.
I have a digital volt meter that I have wanted to install at the power supply to measure volts. It measures voltage from 7.5 - 20 volts. I have though about installing it across the tracks, but haven't had the nerve to do so. Guess it would only cause me grief. Thanks again for your advice. Please keep up the good work that you do for our hobby.

Robert Hughes? Emoji


On Wednesday, February 12, 2025 at 02:52:20 PM CST, Allan AE2V <bigboy@...> wrote:


Hi Jerry,
?
To anyone who wants to try this:
?
1.? Do NOT hook up any amp meter across any kind of power source whether that be a power supply, battery, booster output or across your track.? If you are lucky, all you will do is blow a fuse.? Some amp meters have some hard to find fuses or no fuse at all.? Amp meters must ALWAYS be placed in series with the output of one of the leads from your power source.
?
2.? If you hook up an analog meter (across the power source for a volt meter and in series for an amp meter), be sure to use an AC meter.? A DC meter will read zero.? An AC meter will read low.
?
I have several RRampmeters.? For those that don't think they can afford one, a regular digital multimeter can be used if you don't care about the exact reading.? Quite often, a relative reading is adequate.? For example, say you place your meter across your booster and it reads 6.7V.? That becomes your reference.? If you are using electronic circuit breakers or block detectors, measure at their output and that becomes your reference.? Now if you measure along your track and you get close to 6.7V, you are good.? Sometimes, you just want to know if you have voltage or not.? So while I have RRampmeters, I often just reach for the nearest handy digital multimeter.
?
Allan Gartner
Wiring for DCC
 

I should have written about an ammeter gauge needing to be in line on one side or another. Sorry about that. I should also have given a more detailed explanation of what I would like to do. We have nine power districts on the layout. I was thinking it would be a curiosity or conversation point to install vintage (steampunk) gauges around the layout. There are a lot of interesting styles, cases, and materials of which these are made. However, another thought came to mind. A voltage gauge would probably read as an electrical load and thus indicate the block was occupied which makes the point moot. Would an ammeter also read as a load? Jerry Michels
 

Hi Jerry,

Any half-decent Voltmeter should have an internal resistance that is many orders of magnitude larger than the resistance needed to trip a detector. No worries there. And when measuring amps, the ammeter will only add a very, very slight resistance in series with the track connections, so on its own it will not cause a load at all, and under load it will only reduce the current (but so slightly that you'll never know). No worries there either.

Wouter


On Thu, 13 Feb 2025 at 16:24, Jerry Michels via <gjmichels53=[email protected]> wrote:
I should have written about an ammeter gauge needing to be in line on one side or another. Sorry about that.? I should also have given a more detailed explanation of what I would like to do.? We have nine power districts on the layout.? I was thinking it would be a curiosity or conversation point to install vintage (steampunk) gauges around the layout.? There are a lot of interesting styles, cases, and materials of which these are made.? However, another thought came to mind.? A voltage gauge would probably read as an electrical load and thus indicate the block was occupied which makes the point moot. Would an ammeter also read as a load? Jerry Michels
 

Jerry,
?
An analog amp meter will not read as a load.
?
An old analog volt meter will probably have a high enough internal resistance not to trip a block detector, as Wouter mentioned.? My original analog VOM (Volt, Ohm, (and usually amp) meter) had a load of 20, 000 ohms/per volt.? This was typical of VOMs.? So at 14VAC, that would be 280,000 ohms - to high be trip a block detector.??
?
I don't know what the load would be of analog volt meter.? I would expect it to be about the same as one in a VOM, but you will need to test them to be sure.
?
A simple test of placing an analog AC volt meter across the track to see if the block detectors trip or not should give you reasonable confidence that it will work or not.
?
If you want to place these all around your layout, it may be a challenge of getting all the same meter at a hamfest.??
?
Good luck!
?
Allan
?
 

¿ªÔÆÌåÓý

Hi Robert,

?

You are doing it right.?

?

Many meters today are auto-ranging: They will figure out the range they need to be on, on their own.? Less expensive meters you still have to select the range.? If you don¡¯t know what voltage you will be measuring, set the meter to a higher range than you think you will need and work down.? For most things DCC, the 20VAC range will be what you want.? G-scalers may be operating a little over 20VAC, so they would need the next range which would be 200VAC.

?

For voltmeters, as long as you have them set to a high enough range, won¡¯t be hurt by placing them across the tracks.? If you have it set to volts DC and place it across the tracks, it will read an erroneous value close to 0V. ?It won¡¯t hurt it.? It will just mislead you into thinking you thinking you have no voltage.? To read DCC track voltage, you will need to set it to volts AC.? It will read lower than the actual DCC track voltage since DCC track voltage is special and not what typical digital voltmeters are designed to measure.? Even most ¡°true RMS¡± meters will read low, but better than none true RMS meters.? But don¡¯t worry about that.? Usually, you are just worried that you have track voltage or not and you don¡¯t need to get overly concerned about exactly what that voltage is.? If you are worried about the exact DCC track voltage is, a meter like the RRampmeter (and voltmeter) is one way to get that answer.

?

Allan

?

From: [email protected] <[email protected]> On Behalf Of Robert Hughes via groups.io
Sent: Thursday, February 13, 2025 4:09 AM
To: [email protected]
Subject: Re: [w4dccqa] Retro Ameters and Voltmeters

?

Thank you Allan for the good advice. Although I am by far no electronic person, but when doing anything on my layout that requires a power reading I use an old standby Sears multi-meter.

But not sure if I am doing this correctly so here goes. If I want to measure volts in track power I use my multi meter. I set the selector knob on VAC and attache the probe to the tracks. I get 14VAC on a Digitrax Super Chief DSC100.

I am using a multi adjustable power supply set on 16 volts of power to my command station. My meter doesn't? measure amps AC.

I have a digital volt meter that I have wanted to install at the power supply to measure volts. It measures voltage from 7.5 - 20 volts. I have though about installing it across the tracks, but haven't had the nerve to do so. Guess it would only cause me grief. Thanks again for your advice. Please keep up the good work that you do for our hobby.

?

Robert Hughes? Emoji

?

?

On Wednesday, February 12, 2025 at 02:52:20 PM CST, Allan AE2V <bigboy@...> wrote:

?

?

Hi Jerry,

?

To anyone who wants to try this:

?

1.? Do NOT hook up any amp meter across any kind of power source whether that be a power supply, battery, booster output or across your track.? If you are lucky, all you will do is blow a fuse.? Some amp meters have some hard to find fuses or no fuse at all.? Amp meters must ALWAYS be placed in series with the output of one of the leads from your power source.

?

2.? If you hook up an analog meter (across the power source for a volt meter and in series for an amp meter), be sure to use an AC meter.? A DC meter will read zero.? An AC meter will read low.

?

I have several RRampmeters.? For those that don't think they can afford one, a regular digital multimeter can be used if you don't care about the exact reading.? Quite often, a relative reading is adequate.? For example, say you place your meter across your booster and it reads 6.7V.? That becomes your reference.? If you are using electronic circuit breakers or block detectors, measure at their output and that becomes your reference.? Now if you measure along your track and you get close to 6.7V, you are good.? Sometimes, you just want to know if you have voltage or not.? So while I have RRampmeters, I often just reach for the nearest handy digital multimeter.

?

Allan Gartner

Wiring for DCC

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