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How to Read Voltage With My Oscilloscope

Electricity is created by the flow of charged particles known as electrons. There are two basic of types of electricity: alternating current, or AC, and direct current, or DC. With AC, both the current and the voltage oscillate with time; with DC, the voltage and current remain at a constant value. An oscilloscope is a device that you can use to measure both AC and DC voltage. It consists of a number inputs and controls, and it has a screen that is used to visualize the signal.

Things You'll Need

Oscilloscope
Coaxial cable

Instructions

- 1
  Plug the signal coaxial cable into one of the inputs on the oscilloscope. There are normally two inputs on an oscilloscope, labeled A and B. The signal cable can be plugged into either of these inputs. Turn on the relevant input by pressing the A or B button.
- 2
  Switch on the oscilloscope. The screen should turn on, but some parameters will need to be changed to visualize the signal correctly. Alter the Volts/div knob until a signal shows on the screen.The Volts/div knob changes the vertical scale on the screen and the number of volts each division represents.
- 3
  Alter the time/div, or timebase, knob, which changes the number of milliseconds each horizontal division represents. This setting is particularly important for visualizing AC voltages. In this case, the time/div should be set to approximately 1 / f , where f is the frequency of the signal. DC voltages are independent of time, so the time/div knob has no effect.
- 4
  Measure the voltage. For DC voltages, switch off the DC source. Use the vertical position knob to move the line trace on the screen to the 0V line. Switch on the DC source and measure how many vertical divisions the line has moved. Multiply the number of vertical divisions it has moved by the Volts/div to get the measured voltage. For AC signals, use the vertical position knob to place the peaks of the sinusoidal signal on the 0V line. Measure the number of vertical divisions from peak to trough in the signal. Multiply this value by the Volts/div.

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