Need Help Wiring Staco Variac

[Tone Meister]

I was just gifted a Staco 1520 variac in a nice enclosure, complete with volt and ammeters. I received a basic wiring diagram from Staco, but it doesn't incorporate the 1A/10A switch for the ammeter, a feature I'd really like to have working. All the parts are here and the variable transformer works just fine. And yes, I do realize the meters are probably installed in the wrong spots, but that's an easy fix I suppose.

Can someone help with the wiring, specifically on how to incorporate the 1A/10A ammeter switch? I plan to run it at 120 VAC.

Here is a link to pictures:

Staco Variac Photos by ResidentToneMeister | Photobucket

And here is a PDF supplied by Staco.

[Enzo]

Build what the diagram shows. If that works, then all you need is a meter shunt.

To make a 1 amp meter into a 10 amp meter all you need to do is put a parallel resistor across it for the other 9 amps. Look up current meter shunt or calculating meter shunt or something similar. Maybe contact Simpson and ask if they have a paper on calculating a shunt. Or maybe they have ready made shunts for 10A for that meter.

[Tone Meister]

Thanks Jazz P, I am looking for the documentation on the meter(s) at the moment because I knew full well you folks would start gnawing at my ass from the outset. I did link to some pictures to hold off the wolves for the time being.

Lemme see what I can conjure up for the meters.

[Tone Meister]

Datasheet

OK, the ammeter has no definitive identifying markings, but it appears to be a Simpson Designer Series and the model is one of these two:

Model 524 (catalog #15101) self-shielding movement
Model 554 (catalog #15121) iron-vane movement

The range is 0-1A and I'd like to wire the switch for use with both 1A and 10A scales. Here is the datasheet for the Designer Series meters.