Cliffmeister2000 wrote:NightCap wrote:Do the inexpensive amp meters go inline? For example cut the red wire and insert gauge? Is there a wiring diagram for guages? I have not seen one in my travels through T&TTT.

As I remember it, an ammeter like this is really a voltmeter that measures the voltage drop across a shunt. A shunt is a very exact, very low resistance resistor. The meter is calibrated with Ohm's law, which can be represented as (p=ie, p=i(squared)r, i(squared)r=ie, ir=e, i=e/r (I couldn't figure out how to superscript the 2 to make it represent "squared", so I just wrote squared)

p=power (watts)

i=current (amps)

e=electromotive force (volts)

r=resistance (ohms)

So, with a known resistance, you measure the voltage drop across that resistance, divide the voltage drop by the resistance and you get amps.

It matters little, but I believe an analog ammeter is actually an ammeter. The shunt or resistor is in parallel with the meter to act as a current divider and scale the meter according to the incrementation of the meter scale. A voltmeter is also an ammeter only calibrated to read volts and scaled with series, rather than parallel resistors. In my experience most analog meter movements in common use are actually 1milianmp full scale ammeters with external circuitry to make the readings correspond with the meter labeling and incrementation. The ammeter is placed in series with the current to be read, while the voltmeter is placed in parallel with the voltage to be read.