Oscilloscopes stand out as the go-to measuring instruments for electronic engineers, and accompanying them are oscilloscope probes—indisputably the most commonly utilized accessories. The oscilloscope probe serves as the electronic component that establishes a connection between the circuit under examination and the oscilloscope input.high voltage probe Without the probe, the oscilloscope is reduced to mere decoration.

Prior to selecting an oscilloscope probe, consulting the oscilloscope manual is advisable to comprehend the probe specifications suitable for the oscilloscope in use. Several key considerations should be kept in mind when opting for a probe.

Ensuring compatibility between the system probe interface and the oscilloscope interface technology is crucial.wafer chuck While most probes are designed with a BNC interface for interfacing with oscilloscopes, some oscilloscopes may feature an SMA interface.

Verification that the chosen probe's input impedance and capacitance align with those of the oscilloscope is essential.manual prober This is paramount for minimizing the probe's impact on the test circuit, and the alignment significantly influences the accuracy of measured signals.

Determining the number and types of probes needed depends on specific measurement requirements, akin to the varying lenses required for different scenarios in photography. For instance, measuring DC voltages may necessitate a 1mΩ passive probe, while tasks like measuring three-phase power or relative voltage differences in power system testing may demand a differential probe.

Passive Probes

Passive probes are ubiquitous, often provided by manufacturers as standard accessories when purchasing an oscilloscope. Comprising a probe, probe cable, compensation device, or other signal conditioning network, and a probe connector, these probes lack active components like transistors or amplifiers, eliminating the need for external power. Passive probes are widely used due to their simplicity, ease of use, and cost-effectiveness.

Passive voltage probes offer various attenuation coefficients to cater to different operating voltage ranges. The attenuation feature enables extending the oscilloscope's voltage measurement range by using a corporate internal resistor, forming a voltage divider. This enhances measurements for signals beyond the oscilloscope's voltage technique limitations.

Active Probes

Named for containing active components like transistors and amplifiers requiring power, active probes, often utilizing field effect tubes (FETs), provide low input capacitance and high input impedance across a broader frequency band. Active FET probes typically boast bandwidths ranging from 500MHz to 4GHz. In addition to the higher bandwidth, the high input impedance of active FET probes allows measurements at test points with unknown impedance, minimizing the risk of load effects. The low capacitance also permits the use of longer ground lines, reducing the impact of the ground line.

Differential Probes

Designed for measuring differential signals, differential probes excel at measuring signals from floating devices. Comprising two symmetrical voltage probes with good insulation and high impedance, differential probes offer a high common mode rejection ratio (CMRR) across a wider frequency range. Their advantages include strong anti-interference capabilities, effective EMI suppression, and accurate timing for positioning.

Current Probe

Obtaining the current value traditionally involves dividing the measured voltage value by the measured impedance value using a voltage probe. However, specialized current probes are essential due to the considerable error introduced by this method. Current probes leverage the input of a current transformer to accurately measure current waveforms. AC current probes, usually passive with no external power supply, and ACFDC current probes, typically active, represent the two main categories. The Hall effect allows DC current probes to function as active devices requiring an external power supply.

Probes play a pivotal role in oscilloscope measurements, with their impact on the detection circuit needing to be minimal. Distortion of the signal or changes in circuit functionality due to the probe can result in significantly distorted signals and misleading measurements. The insights provided above cover crucial considerations for the purchase and proper use of oscilloscope probes.