Multimeter

Function

With a multimeter (even a simple one), one can find the reason for a number of electrical failures. It completely replaces the diode proof-lamp. In fact proof-lamps with electric light bulbs should be replaced anyway, because in integrated circuits, they do more damage than good. With a multimeter, one can not only find out if there is voltage, but also how much. Cables, plug-in connectors and coils (windings) can be checked for the passage of continuous voltage. Together with a thermometer, one can even get to the bottom of sensor behaviour.

How it works

There are two areas in the above shown multimeter with which, when using, one must exercise particular caution. If one uses, e.g. the ohm area (resistance), a voltage is laid onto the circuit to be examined by the multimeters own battery. This does not get on well with the perhaps existing voltage within the circuit. This voltage must be completely switched off. The multimeter reacts even more sensitively to current measurement in the milliampere range. If the current allowed here is exceeded, e.g., through direct contact of both measuring cables with a power source (battery), this part of the measuring instrument is gone for good.On the contrary, the voltage- (DCV) and 20A current measurement (DCmA), have no problems with it at all. In addition, because in the automobile, almost only DC voltage is found, one can safely ignore the ranges 'ACV', 'ACA' and 'AcmA'. Only then, must the connection of the red measuring cable fit to the respective measuring range. The black cable should always be plugged into 'COM'. The individual prefixes are explained in formulary.

If one has done a little experimenting with the simple multimeter, one finds oneself wishing for a multimeter with better possibilities:
- multimeters which adjust themselves to the measuring range,
- (inductive) current measurement without opening the connection,
- the measurement of quickly changing voltages. 11/09