Analog Panel Meter?

[Toe Cutter]

This might be a basic question, but I was thinking of getting some analog panel meters for a project. Most of them are calibrated with volts or amps, ac or dc. Like 300 V DC full scale or 10 Amps full scale. Does this mean that the required shunts or voltage dividers are INSIDE the meter? Or would external components be required to achieve the full scale printed on the meter face? I realize the basic meter movement would be 50uA or 1mA full scale (for example). I couldn't find any clear information on this either way.

Also. Has anyone bought analog meters from ebay? I see some really cheap ones from China. Are they any good quality wise? Some others, like the older Weston or GE look nice.

Thanks.

 

[MikeMl]

Shunts for DC Ammeters that have a full-scale reading of more than a couple of A are usually NOT inside the meter. Most of those meters are calibrated for 50mV full scale (usually printed in small print on the meter face). The external shunt is usually calibrated for 50mV at the rated current. For Example, I have some shunts here that are rated 50mV/50A, i.e. 1mΩ.

 

[Toe Cutter]

Ok, makes sense. Big current requires big shunt, which wouldn't fit in a meter, or would overheat.

Would meters calibrated for volts have internal voltage dividers? Or expect an external divider? Thanks.

 

[MikeMl]

Voltmeters usually have the scaling resistor built in. Most voltmeters are intrinsically 1000Ω/V, or 1mA full-scale, meaning that you can convert one that is rated say 10V full-scale to 100V full scale by putting a 90KΩ 1% resistor in series with it.

Hey, you aren't Toe Cutter from rec.aviation. are you?

 

[SABorn]

The meter you pictured would have a in-built shunt and i would say most do up to about 30 amp.

If the meter quotes "universal" than no it wont have a shunt, most on ebay will quote "shunt required" if a external shunt is needed.

Virtual Village on ebay has a good range of analog meters last i looked, and they do quote good information of their products.

Pete.

 

[Toe Cutter]

Nope, never read rec.aviation.