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Electrical Applications | Basic Power Analysis | Accessories | PSU | UPS evaluation | Battery analysis | CCTV camera system troubleshooting => Power Analysis accessories (Test leads, Active & differential probes) => Topic started by: Kiriakos GR on August 17, 2015, 08:30:46 PM
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This small presentation is all about expectations when using a differential probe.
The first personal lesson that I got by purchasing my own AC/DC current clamp probe which this is mainly to be connected to an Oscilloscope is that all active probes even if them measuring nothing, they do output few millivolts and them are described as noise.
At current clamp probes when using them for DCA measurements’, their button about zero-out is very handy, this helps their output to get close to zero, and the actual measurement is close to be called as accurate.
But at active differential probes what ever noise is produced by their own electronics it gets out in the form of some mV and even them are added to the final measurement.
A bit of noise in those Differential probes is not a big deal if you need plain voltage measurements’ at the range of several hundreds of volts.
But when you need to troubleshoot pulses by your Oscilloscope, this output noise it can become your enemy.
The test bed in my testing is a pulsing battery charger, at charging mode this produce a positive pulse so this to charge 1.5V Ni-mh battery.
I thought to test GDS-2102A by using channel 1 with it normal probe, and at channel 2 I did connect the PINTEK DP-50 probe.
The noise of PINTEK DP-50 probe at that low voltage is huge.
Then I thought to use GDS-320 Oscilloscope with GDP-040D so to discover how this performs in the specific application.
The results of my tests are now presented bellow by pictures.
My own fresh experience and lesson is that from now and on I will never use again PINTEK DP-50 probe at probing anything bellow 5V DC.
This GDP-040D shown much better behavior over all, and it did demonstrated correctly the pulse signal with good detail.
To my readers I will say to be careful when selecting a differential probe, my story is one good example of what it can happen when you using probes designed almost one or two decades back with Oscilloscopes’ of our times.