Choosing the best probe for the application at hand is not a difficult process. The first step is to reconcile the actual signal characteristics, the capabilities of your scope, and your expectations. Is the scope bandwidth sufficient? Does it have enough channels to simultaneously present time-related events occurring at different points in your circuit? Are the signal levels so high that safety is your first concern? When these questions are answered, selection becomes a matter of matching probe loading to the signal source impedance. The decision also is affected by how precisely you must measure voltage levels and event timing, what probes you have available, and the size of your new probe budget. Low-cost, relatively low-bandwidth scopes often are supplied with switch-able 1:1/10:1 high-impedance probes. For the types of signals that you can view using a low-cost scope, this type of probe is appropriate. However, if you will be examining 500-MHz ringing on a switching signal, you will need a better scope anyway.
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