I recently picked up an old (antique?) ammeter, mainly because it looks cool, but I'm wondering if there is anything I can "do" with it. It's a Weston model 155, and you can find a picture here: http://www.humboldt.edu/~scimus/HSTC.27-35/Descriptions/ACVMeter155.htm. In short, this is an AC ammeter, marked from 0-300A. I have a couple of questions about it. First, how can I test this? I figured I could shunt this in to my clothes dryer circuit (15A or 30A, I forget), but then again, I might just set the house on fire if I do so. Second, this is an AC meter, and I'm not sure of what the difference between meters. From what I can tell (from this website) is that DC meters usually have a shunt resistor, and that is what gives the rating of the meter. Is there any way I could use this for a toy, perhaps just driving it with the PWM of an AVR microcontroller?