When connecting the oscilloscope to the measured section of
Posted: Tue Feb 18, 2025 4:16 am
When taking measurements, it is important to correctly connect the device to the measured section of the circuit. The oscilloscope has two outputs with terminals or probes connected to them. One loan data is the phase terminal, it is connected to the vertical beam deflection amplifier. The other is the ground, connected to the device body. On most modern devices, the phase wire ends with a probe or a miniature clamp, and the ground ends with a small crocodile-type clamp (see photo)
On Soviet-made oscilloscopes and some Russian models, both probes are identical; they can be distinguished either by the “ground” symbol on the corresponding wire, or by their length — the phase wire is shorter. They are connected to the oscilloscope inputs, as a rule, with a standard plug (see the figure)
If there is no marking and it is not possible to determine which probe is which based on external signs, then a simple test is performed. Touch one probe with one hand, while the other hand is held in the air without touching anything. If this probe goes to the phase input, then noticeable interference will appear on the monitor (see the figure). It is a significantly distorted sine wave with a frequency of 50 Hz. If the probe goes to the "ground", then the monitor will remain unchanged.
the circuit that does not have a common wire, the "ground" probe can be connected to each of the measured points. If there is a common wire (this is a point connected to the device body or grounded and conditionally having a "zero" potential), then it is preferable to connect the "ground" to it. If this is not done, the accuracy of the measurements will drop significantly (in some cases, such measurements will be very far from the true values and they cannot be trusted).
Measuring voltage with an oscilloscope
The known value of the vertical scale is taken as the basis for measuring the voltage. Before starting the measurements, both probes of the device must be short-circuited or the input regulator must be switched to the position. For a clearer picture, see the following picture.
On Soviet-made oscilloscopes and some Russian models, both probes are identical; they can be distinguished either by the “ground” symbol on the corresponding wire, or by their length — the phase wire is shorter. They are connected to the oscilloscope inputs, as a rule, with a standard plug (see the figure)
If there is no marking and it is not possible to determine which probe is which based on external signs, then a simple test is performed. Touch one probe with one hand, while the other hand is held in the air without touching anything. If this probe goes to the phase input, then noticeable interference will appear on the monitor (see the figure). It is a significantly distorted sine wave with a frequency of 50 Hz. If the probe goes to the "ground", then the monitor will remain unchanged.
the circuit that does not have a common wire, the "ground" probe can be connected to each of the measured points. If there is a common wire (this is a point connected to the device body or grounded and conditionally having a "zero" potential), then it is preferable to connect the "ground" to it. If this is not done, the accuracy of the measurements will drop significantly (in some cases, such measurements will be very far from the true values and they cannot be trusted).
Measuring voltage with an oscilloscope
The known value of the vertical scale is taken as the basis for measuring the voltage. Before starting the measurements, both probes of the device must be short-circuited or the input regulator must be switched to the position. For a clearer picture, see the following picture.