EE303LAB05Design of an Ayrton Shunt AmmeterObjectives:To convert a 1-mA ammeter to a 5 mA, 10 mA, and 20 mA ammeters and to design an Ayrton shunt ammeter.Experiment:

If we want to measure a current with a value that is more than the maximum range of a 1 mA ammeter, then the following circuit can be used:

Where and we can apply the following:

So if we want to convert the 1 mA ammeter to a 5 mA full-scale range, then

And if we want to convert the 1 mA ammeter to a 10 mA full-scale range, then

and

And if we want to convert the 1 mA ammeter to a 20 mA full-scale range, then

and

Multi-range Ayrton Shunt Ammeter:We can use the following circuit

Case I (5 mA range): (only use one resistor box)

Here

So, In general

But in our circuit ---------------------------------------(1)Case II (10 mA range): (use two resistor boxes)

Here

So, In general

But in our circuit ---------------------------------------(2)Case III (20 mA range): (use two resistor boxes)

Here

So, In general

But in our circuit ---------------------------------------(3)Solve (1), (2), and (3) simultaneously to get the unknown resistances.