Well, I'm an olde foggy but did plan on analog. It just occured to me, does anyone have a diagram as to where they fit in the wiring?
Doing that with DCC might be interesting. It would be a way to use that particular ammeter without risking burning it out every time you back a train up. I've never used panel meters, though they have always been a tempting toy to me. I inherited an attractive old milliamp meter from the 1940s which does swing both ways, but my elderly HO locomotives refuse to be content with milliamps. I've been tempted to see if I can create an inductive coil to wrap around a track feed wire that will budge that needle, but that hasn't found its way to the top of my priority list yet.
I used them on my previous railroad, both Volts and Amps using analog meters with a zero reading at the center of each scale. I found them at a train show somewhere long ago. Being short on panel space, I didn't provide for them in my new design, but I can always add them later elsewhere. I didn't think about DCC's effect on them until I read acptulsa's post.
I kind of figured with DC, that particular amp meter wouldn't work but should show a good reading with DCC. On the volt meter, I would expect to see a change as the throttle is turned up in DC and pretty much a constant on DCC. Am I right about that? I have a pair similar to these tucked away somewhere and was thinking I should find a use for them that doesn't involve collecting dust in a drawer. Not sure if the amp meter I have is zero center or like the one in the pic with zero left. Would add some interest to the control panel I think.
Something will go up when locomotives are actually hauling weight and overcoming friction. Wattage certainly will. Most electronics seem to prefer constant voltage, so I assume DCC is set up to maintain voltage and increase amperage as needed (unlike DC). But I'd be interested to know if my assumption is right or wrong.
Well, you could feed a one-sided DC amp meter like that through a bridge rectifier, and then put the polarity reversing DPDT switch after the meter. That would prevent somebody from burning out the meter by throwing the direction switch on the power pack. But, you would need to show the uninitiated that DPDT switch, or they might not figure out why they could only run analog trains in one direction.
I was thinking if the Amp meter was connected to a bridge, you would not need a DPDT. The bridge would take care of the current flow regardless of the direction switch on the power pack. The bridge would only be on the positive wire, one side of the bridge would be the positive wire from the power pack and the layout and the other side of the bridge would be the amp meter. You'd want a second bridge that was connect to both the positive and negative wires for the Volt meter.
OOPs, brain fart. You are right about the ammeter. The meter goes across the bridge path, so the current only goes through it in one direction, no matter which way the current is flowing through the track bus wire that the bridge is inserted into. The volt meter would need its own bridge rectifier with its leads bridging the 2 track feeder wires.
Finding the right ones for Analog DC and/or DCC is the difficult part. One being DC current and the other AC. Not interfering with the DCC coded messages to the decoder is another. But for Analog DC it's easy as wiring in a light bulb. Find a 12 volt meter and wire it in as per instructions. Easy drill sergeant to easy.
Radio Shack is on line now and you can pretty much order what you used to. I keep getting Internet advertisements via e-mail. They got my number. Grin! You should be able to find an online catalog. Best of luck.
We disassembled one of our members layout the other day and it had a Varney voltage meter on it. I made sure that it was saved. I'll try to remember to take a picture...
The best thing about meters is you can immediately tell what's going on. Say, for instance, a loco stalls on a switch. Looking at the meters, you know, right away, whether it has lost contact or if it has shorted across something in the switch. It can save plastic parts from being melted down. And yeah,it would be great to see that Varney meter. Doug