Essential Ideas in Electronics: Voltage (Part 1)
Fig 3 shows the same circuit made up with System Alpha boards; again, if you have access to Alpha boards, you can try this circuit out as well. In fig 3 an electronic bar graph is showing the signal level and giving a rough idea of the voltage.
As fig 4 shows, instead of using the bar graph you can attach a voltmeter to any of the signal connectors to get a more precise reading of voltage. Notice that, in fig 4, the voltmeter has two connections; one to the signal connection and one to the connection marked with a minus sign. You’ll see why two connections are needed later in this article.
In summary, the signals in an electronic system are actually voltages and they can be measured with a voltmeter.
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