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How to Detect Low Voltage Pulses on a High Voltage Line

Voltage is defined as being the potential energy per unit charge, and is essentially a measure of the average energy that electrons have in the circuit. The most common type of electricity is known as direct current (DC) and operates at constant voltage. Alternating current (AC) electricity has a time dependence of the voltage and current. This time dependence can take a sinusoidal form, as it does in home electricity supplies, or come in the form of pulses as it does in some laboratory experiments. The detection of low voltage pulses on a high voltage signal line can be carried out with the use of an oscilloscope.

Things You'll Need

Oscilloscope

Instructions

- 1
  Plug the signal line into one of the oscilloscope inputs. There are normally two inputs on an oscilloscope and these are labeled "A" and "B." Switch on the appropriate input by pressing the "A" or "B" button.
- 2
  Turn on the oscilloscope. The high voltage offset of the signal line will lead to a vertical shifting of the trace. Use the vertical position control to move the trace down onto the zero level mark.
- 3
  Adjust the "Volts/Division Control." To detect the small voltage pulses, the volts/division needs to be reduced to one of the minimum values. The volts/division control adjusts the vertical scale, and the number of volts each vertical division represents. As the volts/division control is modified, ensure that the trace remains on the center line, by modifying the vertical position.
- 4
  Adjust the "Time/Division Control." The time/division control adjusts the horizontal scale and the amount of time each horizontal division represents. In order to see the pulses, the time/division needs to be reduced to a time less than the pulse width. The trace should now be capable of showing any low voltage pulses coming across the high voltage signal line.

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