Recently, a lot has changed for the better in the market of measuring instruments. Compact digital multimeters have appeared on sale, designed to measure current, voltage, resistance, which operate in a fairly wide range. Many of them are equipped with additional functions, for example, they can work in the "continuity" mode of the circuit or measure the coefficients of transistors. They invariably include a digital voltmeter. Voltage measurement is the main stage in the development, repair or adjustment of electronic devices of any complexity.
Having a digital voltmeter in your home lab is essential for many reasons. Such devices are compact and quite reliable in operation. Moreover, without measurements, the operation of a radio amateur is impossible, and a lot depends on the quality of the measurements made. The main difference of these devices from analog "compatriots" is high internal resistance, which is the guarantor of correct readings when working in low-current circuits. DC digital voltmeter able to measure output voltagemicrocircuits and not “squander” the electrical circuit. This is especially true when working in process control circuits. Any interference in this case can lower the control voltage level and cause the entire process line to fail. Digital devices are free from this drawback and are absolutely safe to use.
But not everything is so “cloudless”, and you should not fully trust the latest in the field of measuring instruments either. The digital voltmeter behaves very poorly on line and in AC circuits. In other words, when trying to measure a long electrical circuit, given a small load on the output of this circuit, we are likely to get wrong results. This may be due to the high level of “interference” that is superimposed on the main signal. Also, a digital AC voltmeter is designed to work in standard frequency circuits and, when it changes, it starts to work with errors. The same can be said about work in circuits with electric voltage, which differs in shape from a sinusoid (triangular, rectangular, etc.).
Ordinary pointer device in this respect is much better than its digital competitor. It has a low input impedance, and when working with a line, it will “sag” all pickups and show the real voltage in the network. As for voltage measurements of non-standard frequency, the device does not know what fifty Hertz is. It will show the average measured value.
Based on the above, we can draw some conclusions. A digital voltmeter is useful in a home laboratory, for example, when repairing electronic circuits. This device performs best in short DC circuits.
The best option is to equip your laboratory with several types of measuring instruments, so to speak, “for all occasions”. In this case, you will be well prepared and will surely be able to solve any, even quite complex, task.
