I have some DC volt and amp meters that I want to connect to a DC track and am not sure how to connect them both. I understand the amp meter is to be in series and the volt meter in parallel. Is this schematic correct or does it need some changes. I have never done this install before. Thanks for any help.
-Bob
Life is what happens while you are making other plans!
Your setup is correct Bob. Just remember that if you are going to use a reversing switch it goes after the meters.
Joe
Good point Joe, I wasn't sure about reversing the loco and what effect it would have on the amp meter.
Unless you use center scale meters, it can damage the meter to put the power through the wrong way. Since you are les likely to hit the max scale on the amp meter, it would just be annoying, on the volt meter though, you can easily hit 12 out of 15 or so, and pushing too hard the wrong way can damage the movement.
A center scale meter has 0 in the middle and can move either way, downside is not as much 'resolution' since just half the scale is 0 to max, on either side. Also, center scale meters are usually a lot more expensive.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Our club did this years ago with a center scale DC 20 volt meter. Both meters became useless when we switched DCC.
DCC was not even in our thoughts back around 1985.
We built our own DCC amp meters for about $10.00.
A cheap digital meter, about $5.00 works just fine.
Reads about 13.6 VAC with the NCE Power Pro.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
richg1998 Both meters became useless when we switched DCC.
Rich.
On the contrary. The meters can go between the power supply and boosters/ command station. This is a great way of seeing the actual draw of a given power district. Makes trouble shooting strange problems easier. Just a couple of examples. One district was showing signs of loco stalling and unresponsive throttles. One look at the amp meter saw the needle jumping. Turns out one side of the buss was not soldered to the feeders. Another time when three or four locos entered a district the district would shut down. Both amp and volt meters would drop. The power supply had gone south.
So don't give up on those old meters yet.
Sorry to the OP for the hijack.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
That will work if you power your DCC system with a DC source. More recently that's becoming common - since there are plenty of surplus laptop power supplies that put about about the right voltage and amperage. But it used to be all AC powered, so you need an AC voltmeter to replace the DC one. Same with the ammeter. Most moving coil type as DC only.
Now this would look cool: http://www.ebay.com/itm/New-AC-Digital-Ammeter-Voltmeter-LCD-Panel-Amp-Volt-Meter-100A-300V-110V-220V-1-/380752683639
and it uses a toroid for current sense so you don;t even have to wire it in series. Hmm, master control panel for the train room, with each circuit monitored for power and voltage - lights, DCC power supplies, accessory power supplies....
locoi1sa richg1998 Both meters became useless when we switched DCC. Rich. On the contrary. The meters can go between the power supply and boosters/ command station. This is a great way of seeing the actual draw of a given power district. Makes trouble shooting strange problems easier. Just a couple of examples. One district was showing signs of loco stalling and unresponsive throttles. One look at the amp meter saw the needle jumping. Turns out one side of the buss was not soldered to the feeders. Another time when three or four locos entered a district the district would shut down. Both amp and volt meters would drop. The power supply had gone south. So don't give up on those old meters yet. Sorry to the OP for the hijack. Pete
We thought of that but really did not need them anymore. Unless we would want to look for a trend which analog meters are good for, the digital meters worked really well.
I didn;t save it, but while looking at AC ammeters on ebay, where I found the digital one, if you want a more 'period' look, there was someone selling an antique (early 1900's) analog AC ammeter, and he says it works. I wouldn;t hook it to 120VAC, but 15 or so coming from a DCC power supply - that would look neat, if it really does work. Or a set of those vintage black bakelite ones that I would say were from the 20's and 30's.
Randy,
I recently sold a pair of old Varney meters; one ammeter and one DC voltmeter; both were black enamel cases with a 1 1/2" thick wood case. They both worked but I had no use for them. Almost kept them for another 20 years just because they looked so 'neat'. Here's a photo I took back in '08.
That is because they are designed and calibrated to read accurately a sine wave at 60Hz. Outside of that you will get interesting results.
Voltmeter readings will never change if measuring track voltage with DCC - it's a constant voltage to the rails. The only place it changes is inside the loco, on the wires connected to the motor.
I understand that the voltage doesn't change in DCC, but shouldn't it be higher than 5-7 volts? I though DCC ran around 13-15 volts. The amperage is where I expected to see some variations when running several locos. Are the new DCC sound locos that efficient that they don't draw much amperage?
Sounds like your volt meter is a DC one. My didigtal multimeter, in AC volts mode, reads around 15 volts, about where it is supposed to be, and that's not some fancy meter than can handle the square wave of DCC, it's the cheapy Harbor Freight model. A DC meter with address 00 in use will show a gradually increasing value as you throttle up (or bang the needle the wrong way if you ahve the polarity wrong). With Address 00 at stop, a DC meter shoudl effectively indicate 0 volts, since the pulses should be as much negative as they are positive. In practice, a DC analog meter on an AC source will damage itself since what it really is doing is trying to swing back and forth at a rapid rate.
Rob Paisley has a simple circuit for DCC current measurement, essentially what's inside the RRampmeter, for a couple of bucks. It's designed to work with a digital voltmeter, you can get an LED panel meter cheap on eBay. For voltage measurements, a simple snubber circuit works, it's on one of the DCC sites, I think Wiring for DCC. Since there are diodes involved, the registered voltage is slightly less than what's actually present. If you're the type who likes to experiment a little, with these circuits youc an build your own equivalent of the RRampmeter for maybe $30 tops.
I just bought the volt meter and ammeter from LED-Switch Co and they are both AC versions. I can see a slight increase on the ammeter and the volt meter doesn't go much above 7-8 volts except when I run a DC loco using the 00 address, then the voltage goes up to 10 or 11 volts. I have a couple of the Harbor Freight digital meters but the AC range on it seems too high to measure such a small amount on the track. I am not a 'electonics' person, but know enought to do most of the layout and loco/decoder work. Maybe I know just enought to be dangerous?
I started this whole 'meter' thing because I thought it would be a good idea to see what is happening with the electric load aspect of the layout when trains are moving. Maybe I don't really need this feature? Thanks for all the help and info