Voltmeters - the charm of old devices
Analog voltmeter, or indicator voltage meter, is the longest type of voltage indicator on the market. In the past, each voltage indicator, from a simple amp meter in amplifiers and cassette recorders, to the high class laboratory equipment, was equipped with the so-called measuring "circuit". The principle of operation of such an element is very simple: the flow of current through a light, delicate coil connected to the pointer, causes it to rotate in relation to a permanent magnet. The angle of deflection depends on the current intensity, which in turn - with a specified coil resistance - is proportional to the voltage at its terminals. Thus, it can be seen that the same measuring instrument, depending on the additional resistors connected (or not), can serve as both an ammeter and a voltmeter.
Modern applications of analog indicators
Today, despite the widespread availability of digital devices and their low price, pointer voltmeters and ammeters are still readily used. As an example, let's take old-style devices - audio tube amplifiers are the best proof of the continued popularity of traditional indicators. Also simple power supplies, including laboratory power supplies, are often equipped not with a typical LED display, but just an analog voltage indicator. Inexpensive everyday electrical devices, such as car chargers, also often use indicator meters.
Voltage indicators, or can you "see through walls"?
Yes, of course, if we mean the detection of hidden wires or metal parts in walls. For this purpose, voltage detectors are used, which are able to detect, from a short distance, electric cables through which current flows or magnetic field disturbances caused by metal objects (e.g. rebar). For installers and do-it-yourselfers, a "pen" voltage indicator will also be a great help, which will easily identify the phase wire in an electrical installation.
