How to use a multimeter 1

This section describes the functions and use of a digital multimeter or DMM.

•Function: A DMM gives a numerical digital display of measured value and has multiple functions like measuring voltage, current, resistance…. •Only necessary info will be presented for working on light strings. Refer to http://learn.adafruit.com/multimeters/overview for detail.

 

HINT: •Don’t buy a multimeter with a pointer or needle. They’re more difficult to use and can be easily blown up. A DMM is more rugged, error tolerant instrument. You might find an auto-ranging DMM is worthwhile.

 

•Note: Your DMM may be different to the one shown. However, the operation will be similar – refer to your DMM manual for these points:

• ØLow DMM battery indicator - can cause incorrect measurements.
• ØOverload display (is it ‘1   ‘, OL ?), connections for current, rotary switch selections and operation, auto off operation.

HINT: Always ensure the black lead is in DMM’s COM terminal to stop inverted polarity measurement. This is an easy mistake to make.

We'll see how to use a DMM in following sections.

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