Making the most of your digital multimeter
You already know how to measure AC and DC voltages. But how well have you utilised the other functions on your digital multimeter? Have you ever used them? The "Min/Max/Ave" function is a very useful but often overlooked function.
Minimum/Maximum/Average
Many high performance digital multimeters have a min/max recording function that allows the user to capture a variety of signal anomalies such as multi-cycle dips or spikes, unexpected signal fluctuations, or other types of unattended signal monitoring. This function works by sampling the input signal approximately every 100ms or more and can be applied to all major instrument functions (voltage, current, etc.).
When the Min/Max/Ave function is switched on, the instrument captures and temporarily holds the highest and lowest signal levels it has measured. In addition, the meter will hold the average of the signal levels measured during monitoring. The average reading can be used to smooth out noisy signals, analyse the percentage of time a circuit is active, and determine the overall instability level of the monitored signal.
Time Stamping
In addition to capturing these level values, some digital multimeters have an elapsed time clock that allows time stamping of maximum, minimum and average values.
The time stamp tells you when these readings occurred, based on the start of the monitoring process. The actual start time of the min/max record is also displayed, making it easier to determine when a signal change has occurred.
Knowing when the maximum and minimum signal changes occurred allows you to know when an abnormal event has occurred and provides insight into the stability of the signal or system being analysed. If you are looking for intermittent or unusual system performance that occurs when you are not on-site, this is a time-saving feature of the troubleshooting tool that has real value.
