Learn about Oscilloscope Probes
A quick guide for buying the right Oscilloscope Probes
To aid our valued customers in making the most educated probe purchase for their oscilloscope, we have put together some oscilloscope probe buying basics.
To select the best value in a replacement probe, first choose based upon capability, then on price.
Helpful Buying Tips:
- Buy a replacement probe that is equivalent or a little higher than your oscilloscopes bandwidth. Design intricacies and cost rise as compensations are incorporated for higher bandwidths, therefore buy only the bandwidth capabilities you need.
- All x10 oscilloscope probe designs are high impedance to prevent inadvertent circuitry loading. Be sure capacitive trimmer compensation (and an adjustment tool) is provided of sufficient range to include your model oscilloscope. Matching allows for the fastest rise and truest representation of higher speed signals.
- The probe tip should be robust; but also replaceable to extend your investment.
- Buy a probe which is accessorized so you are prepared for any probing need.
- If your oscilloscope has readout actuator capability with an onscreen calculation and numeric display, invest a few dollars more in a probe with a readout actuator feature to better make use of your oscilloscope.
What is an oscilloscope, and why do I need one?
One of the most versatile instruments needed by all electronic technicians is the oscilloscope. An oscilloscope allows you to conveniently see the wave shape of an electrical signal on screen. Since the horizontal sweep rate and vertical deflection can be calibrated, this offers an accurate method for measuring frequency waveforms and peak voltages at-a-glance.
Comparing the horizontal width of a signal, in calibrated divisions, to a set sweep time per division offers an actual measurement of the waveform's (time) period; an exact reciprocal of frequency:
f = 1 / t
...where f is the frequency in hertz (cycles per second) and t is the period in seconds.
With or without modern enhancements, the oscilloscope remains the most versatile instrument available for following signal paths through circuitry.
Why is the bandwidth of my oscilloscope important?
The bandwidth, in Megahertz (MHz), of your oscilloscope designates the highest calibrated frequency for accurate viewing on your oscilloscope as determined by its input vertical amplifier and triggering circuitry design.
Modern oscilloscope designs incorporate self calculation and digital displays to provide the convenience of built-in frequency calculation and voltage level calculation of the displayed signal.
What is an oscilloscope probe?
Oscilloscope probes are more than a conduit for gathering signals, they are specific tools created to protect your device under test with pin point tips, sprung hooks, grounding clips and load reducing high impedance.
Modern enhancements include switchable x10 attenuation for probing versatility and an extension of the oscilloscopes vertical input range. A readout actuator allows for the best use of today's on-screen mathematical vertical display calculations.
Why should I replace my old oscilloscope probes?
Oscilloscope probes, like any tool, wear over time.
For oscilloscope operators and the device under test safety, it is important to not use cracked or broken probes.
Having the proper accessories available is of an equal importance to assure minimizing accidental pin shorting when probing circuitry. Tips and hooks should always be carefully stored and easily accessible to the technician.
The best safeguard for extending an oscilloscope probe's life is to store your probes fully extended using a probe hanger rather than coiling them, wire products weaken faster with frequent bending and unbending. New oscilloscope probes arrive coiled from the factory as a shipping convenience. We recommend storing your TEX series probes using a wall-mounted Pomona 4408 .320 diameter cable holder.
In Summary
When buying a replacement oscilloscope probe you should first ensure the replacement probe best matches your oscilloscope's bandwidth and has sufficient compensation range for matching the input capacitance. The bandwidth rating of the probe should be wide enough to cover the high end frequency capability of your oscilloscope.
Next, look for a probe with a signal attenuation and cable length that best fits your needs. Keep in mind that the lower input impedance of a 1x probe will load your circuit the most, making a 10x setting more desirable for in-circuit probing.
And finally, remember the shorter the cable and the grounding lead, the truer your display is to the actual monitored signal.