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Is it possible to measure waveform of current with current probe connected to analog oscilloscope? Or is that possible only with digital oscilloscope?

Are there any other instruments out there that can display waveform of measured current?

Keno
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  • Put a low-ohm shunt resistor in-line with the load being measured (low enough that its value is negligible compared to that of the load) and probe across it. The current will be the displayed waveform divided by the shunt resistor value – DerStrom8 Sep 26 '17 at 16:51
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    Current probes are rated mA/V and scopes are V/div so you end up with mA/div if you follow directions. – Tony Stewart EE75 Sep 26 '17 at 17:35

2 Answers2

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Oscilloscopes show you a signal as a function of time. That's what they do. It doesn't matter whether they are analog or digital inside.

As long as this current probe produces a voltage signal, it can be displayed on a oscilloscope.

Olin Lathrop
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  • Yes, but input circuits probably differ between analog and digital ones, right? – Keno Sep 26 '17 at 17:18
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    @Keno - no the input circuits are pretty much the same (apart from evolution since digital scopes will be designed more recently than analog ones). The later stages of the circuitry will differ of course with either an A/D converter or a CRT. – Kevin White Sep 26 '17 at 17:55
  • @Keno: Pretty much every scope, old or new, has inputs with about 1 MOhm resistance and 10-20 pF capacitance. From the outside, there is electrically very little difference between a wide range of scopes. And, the differences there are have nothing to do with digital versus analog. – Olin Lathrop Sep 26 '17 at 20:40
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Yes, current probes are commonly used and have 'scope connectors.

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Figure 1. A Fluke 80i-100s AC/DC Current Probe provides fully isolated measurement of cable current.

This probe probably uses a Hall sensor inserted into a slot in the split core.

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Figure 2. A home-made Hall current sensor. The wire to be monitored is passed through the core centre. The chip measures the flux density across the core gap and an output voltage is generated proportional to the current.

If only AC is being measured a passive coil-type clamp-on CT probe is available. These will be less expensive and don't require batteries.

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Figure 2. A Rowgowski 'scope current probe. Source: GFUVE.

Current probes are also available for PCB current measurement. See my answer to Finding a faulty chip that draws too much current.

Or is that possible only with digital oscilloscope?

The probe won't know what it's feeding. The oscilloscope won't know what is feeding the signal. Either type of oscilloscope just sees a voltage varying with time.

Links to other related answers of mine on this topic:

Transistor
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  • I like the homemade probe. Funny how proprietary connectors obviously have led people to believe only certain scopes work with certain probes. – zebonaut Sep 26 '17 at 17:21