How to choose the right oscilloscope probe for power supply ripple testing?
The main function of an oscilloscope probe is to introduce the measured voltage signal from the measurement point into the oscilloscope for measurement. In order to ensure the accuracy of the measurement, it is important to choose the right probe. So how to choose the probe? Oscilloscope probe "Wata" how to do? And listen to Antai test Ma said:
1, how to see the range of the oscilloscope probe?
Oscilloscope probe range general passive probe maximum voltage of 300Vrms, high-voltage probe or differential probe range can be based on the model to find specifications, different attenuation ratios under the different ranges. When using the current gear to determine the maximum voltage allowed to input.
2, oscilloscope probe probe broken how to do?
Nowadays, the probes are usually equipped with a spare probe, use pliers to take down the bad probe in the right direction and replace it directly. If you don't have a spare probe, you can ask your local dealer for original parts.
3 What should I do if the noise floor of the oscilloscope probe is too large?
Connect the probe to the oscilloscope to see the oscilloscope on the waveform noise, is normal, this is because there is no closed loop coupling into the space noise caused by. The positive end of the probe and the ground line closed connection, you can see the current real noise floor.
Generally in the measurement process found that the noise is too large, you can take off the earth wire, with ground spring measurement, especially high-frequency signals.
4 Oscilloscope probe measurement signal overshoot, oscillation obvious how to do?
Significant overshoot or oscillation on the rising edge of the measured signal is generally caused by an excessively long earth wire. Changing a ground spring can eliminate this effect, and measure the true rising characteristics of the signal.
5 What is the reason for inaccurate voltage measurement by the probe?
Probe voltage measurement is not allowed to check whether the probe attenuation ratio and the oscilloscope set up the same, and secondly, to consider the load effect of the probe, if the output impedance of the circuit under test is large, then the general passive probe can not be measured, you have to change the active probe (active single-ended / differential probe), which is due to the impedance caused by the problem of voltage division.
6 power ripple test how to choose the right oscilloscope probe?
Power ripple test is best to use a high resistance passive probe 1X gear, the advantage is that it does not need to go through the oscilloscope internal amplification noise is small, high signal-to-noise ratio. Measurement with a ground spring as the ground, the oscilloscope set the bandwidth limit of 20MHz, according to the need to select the channel coupling for the AC coupling, so that you can observe the power supply ripple and other low-frequency small-signal measurements.
7 current probe wire position changes in the measured value drift, how to ensure the accuracy of the measurement?
Large current measurement with a similar flexible current probe, Roche current probe, its current ring is relatively large, through the wire position will affect the measured value of a slight movement, it is recommended to fix the current flow through the wire in the current ring in the middle position. If you want to reduce the position of the error caused by the current ring can be used with a small diameter current probe. For small currents it is recommended to use a multimeter or a Picoammeter.
8 Can ordinary passive high resistance probes measure utility power?
The mains waveform is 220Vrms sinusoidal waveform, which can be measured with passive high resistance probe 10X, and its maximum input voltage is generally 300Vrms, which is greater than the mains RMS voltage.
However, note that the CAT II level of the passive probe 1X is only 150Vrms, which means that the maximum voltage allowed in the indoor socket environment can only be 150Vrms, which does not satisfy the voltage limit of 220Vrms for measuring the mains, although the voltage passed into the oscilloscope under the 1X gear is 220Vrms, and direct measurement of the mains with the 1X gear will damage the probe.
If the coaxial cable is used to introduce the mains directly into the oscilloscope, in this case, although to avoid damage to the 1X probe, the maximum input voltage from the oscilloscope can be seen from the indicators, the safety level is reduced to CAT I level, in principle, is not suitable for such measurements in the laboratory. Therefore, it is recommended to use a high voltage probe to measure the mains voltage.
