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The input circuit for the amplified voltmeter explained before worked as a voltage divider, with a range switch set up to apply about 0.5-volt signal input to the amplifier for each range position. A similar action must be performed by the input circuit of the amplified ammeter. The input network, though, is not a voltage divider, but is a group of high-precision, low-ohm resistors that can be connected in different combinations by the range switch to produce about 0.5-volt signal level for each range setting, as determined by Ohm\u2019s law.<\/p>\n
Since the current being measured is initially converted to a signal voltage,\u00a0<\/em>the amplifiers utilized in the amplified ammeter can be the same as those used in the amplified voltmeter. There can be differences, since the input circuit of the voltmeter must be a high resistance, while the input circuit of the ammeter must be a low resistance. The FET follower circuit was used as the first stage in the voltmeter because its high input resistance would not load down the input network as would a junction transistor. Since the ammeter input circuit uses low resistances, a junction transistor can be used with little loading effect. Usually, for simplicity\u2019s sake, the same amplifier stages are used for both meter measurements since the same signal voltage can be used.<\/p>\n <\/p>\n Sources:<\/p>\n https:\/\/www.digikey.com\/en\/articles\/fundamentals-of-current-measurement-part-2-current-sense-amplifiers<\/a><\/p>\n https:\/\/www.electronics-tutorials.ws\/amplifier\/amp_1.html<\/a><\/p>\n![\"\"](\"https:\/\/www.apexwaves.com\/blog\/wp-content\/uploads\/2020\/08\/electricity-4627184_1920.jpg\")
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