**milliamp meter**can be used as a

**volt meter**by adding a

**series resistance**. The resistance needed is the full scale voltage reading divided by the full scale current of the

**meter movement**. So, if you have a 1

**milliamp meter**and you want to read 0-10 volts you will need a total resistance of 10/.001 = 10K ohms.

The

**meter movement**itself will have a small resistance which will be part of the total 10K resistance, but it is usually low enough to ignore. The

**meter**in the example below has a resistance of 86 ohms so the true resistor value needed would be 10K-86 or 9914 ohms. But using a 10K standard value will be within 1% so we can ignore the 86 ohms. For a full scale reading of 1 volt, the meter resistnace would be more significant since it would be about 8% of the total 1K needed, so you would probably want to use a 914 ohm resistor, or 910 standard value. The

**milliamp meter**can also be used to measure higher currents by adding a parallel resistance. The

**meter resistance**now becomes very significant since to increase the range by a factor of ten, we need to bypass 9/10 of the total current with the parallel resistor. So, to convert the

**1 milliamp meter**to a

**10 milliamp meter**, we will need a parallel resistor of 86/9 = 9.56 ohms.