Tonal Electrostatic Voltmeter Device

An excellent way to provide continuous and direct indication of ESV readings in even a large lecture hall is to combine this instrument with a tonal voltmeter (TVM). The TVM puts out an audible tone of constant amplitude, with the frequency related to the voltage reading. To integrate the TSV with the ESV, the ESV must have bipolar analog output.
Tonal Electrostatic Voltmeter Device - schematic

Some intermediate frequency in the middle of the audio range is chosen arbitrarily as the zero reference for uncharged objects. Then, an upward frequency shift of the audible tone indicates positive charge while a downward shift indicates negative charge. The larger the positive or negative frequency shift, the larger the magnitude of the positive or negative charge being detected. Experience with the TESV in many lecture presentations indicates that even a large audience is quickly trained to distinguish between positive and negative charges. The TESV shown above consists of a commercially made, hand-held electrostatic voltmeter and a self-contained tonal voltmeter module. Many ESV instruments, including the one shown, come standard with ½2 volt analog output plugs on the bottom. Two jacks mounted to the top of the tonal voltmeter module plug directly into these plugs to make a compact system for detecting electrostatic charge. A volume-control knob and on/off switch are evident on opposite sides of the TVM module and the audio speaker opening is on the front. A very convenient way to use the TESV is with the unit mounted on a short camera tripod. The tripod makes it easy to measure charge quickly and repeatably, and it frees a demonstrator`s hands for other tasks. For example, a great variety of tribocharging phenomena can be demonstrated easily using this arrangement. The tripod-mounted TESV is also convenient in...

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