Forgive the newbie question but I’m wondering how important is resistance, amprage, and voltage in MRR? I’m a maintenance supervisor and deal with electricity every day but of course on a bigger scale. 110v, 220v, etc. How accurate of a meter do I need to get? Should my work one be ok?
Depends on what you’re using at work. I can answer for HO scale, since you didn’t state a scale. Most Amp meters in a standard multimeter should be OK, as long as they have a high enough range. Since you’re dealing with DC, obviously you can’t use a clamp on type, you’ll have to tap it into the line. Some of the older open frame motors can draw up to a full amp for each motor. The newer can motors much less.
A basic understanding of ohms, volts and amps is useful, but not absolutly necessary.
As long as your meter can read DC voltage between 0 and 20 volts and amps between 0 and 5 amps you should be good. Obvously, using the 0-20 range is more accurate then the 0-100 range.
Nick
If you run DCC, then it might help to have AC on the meter, too. Of course, any standard multi-meter has that. I use the Continuity check buzzer on mine to look for shorts, too.
A general meter should work for construction. Resistance is only checked for the extremes – short and open circuits.
Modellers used to build controllers with both amp and voltmeters in them - 5-0-5 amps and 20-0-20 volts if installed after the reversing switch. A meter with a needle is better than a digital display for running or testing locos because the current can vary a lot.
Without electricity you have to pu***he trains around the track, kind of boring… Maybe we could use the kids wooden train sets instead?
When running DC with a power supply with meters in it I’ve found that the ammeter is more important, not for the absolute reading it gives me, which is educational, but for the relative numbers. When the current starts to bounce on the meter I know the track or locomotive wheels are starting to get dirty. The voltmeter comes in handy only to tell me where 12 volts is at the knob. Since everything’s rated for 12 VDC I chose to stop there under all conditions.
As for which multi-meter to use, I’ve got a $65 one I got from Home Depot that is over-kill for my needs with my DC layout. I’m guessing that it’ll do just fine as well when I convert over to DCC. I use the continuity tester when I put together all of my track feeders, not worried about the ohm reading.
Mark in Utah
The standard AC/DC/Ohms multitester will not be accurate with DCC. DCC is a square wave AC. The normal multitester is made for sine wave AC. There is a meter made for DCC. I believe it is called RRamp. Check on the DCC posts for the name.
One way to check DCC track voltage is to measure the motor output leads from a decoder that has the engine speed set to max. It will be the track voltage, or at least very close.
If you have a true RMS voltmeter you shopuld be fine. Many $65 voltmeters are true RMS reading. Some $150 units are not. Be sure to check them out.
Some cheaper voltmeters take shortcuts that get them into trouble when the voltage is anything different from flat DC or smooth AC.
Mark in Utah