Rigol DS2102A Why only 10x probes and not 1x : 10x? - Page 1
Forum section: electronics / testgear

author: Ecklar
author_rank: Regular Contributor
timestamp: December 02, 2014, 09:22:12 pm
content: Will shortly be buying my first oscilloscope for general hobby, fun and education.I studied the topic and set aside the money and decided to just go aheadand get it and begin experimenting and learning rather that talking for months.I decided on the Rigol DS2102A for the first scope but I have a probequestion. Why do they include only a 10x fixed attenuation probe andnot a switchable 1x : 10x? It seems limiting. The scope range goes down to500uV. Will I be able to effectively take advantage of this with the includedprobe? Any other comments you have on this topic or that scope would beappreciated.Ecklar

author: marshallh
author_rank: Unknown
timestamp: December 02, 2014, 09:32:44 pm
content: There are very few applications for 1x probes, compared to the amount of use a 10x gets. Cost savings, plus fixed 10x probes can have better characteristics.Nothing stops you from buying other probes.

author: tggzzz
author_rank: Super Contributor
timestamp: December 02, 2014, 09:37:47 pm
content: Quote from: Ecklar on December 02, 2014, 09:22:12 pmSwitches add a failure point, and arealwaysin the unexpected position.Be aware that the "*10" is done to increase bandwidth and reduce capacitative loading.At frequencies of a few hundred MHz, so-called "*10 low impedance Z0" probes have alowerimpedance than the standard 10Mohm *10 probes. See many other threads on this forum for pointers.

author: tautech
author_rank: Super Contributor
timestamp: December 02, 2014, 10:07:17 pm
content: You must also need to be aware ofprobe voltage de-rating with frequency.This problem is reduced with x 10 probes but not eliminated.Also as most Rigol DSO's have max only 300 V ch inputs the fixed x 10 probe adds an additional safety factor for the only 300V the inputs can manage.

author: LaurentR
author_rank: Frequent Contributor
timestamp: December 03, 2014, 01:50:06 am
content: Quote from: tggzzz on December 02, 2014, 09:37:47 pmThis.On my DS1000Z, the switch is pretty weak and I constantly find one probe or another in 1X mode after some shuffling and lose a good 30s trying to figure out what's going on. Since I have no use for 1x mode, I think I am going to tape those switches...

author: Ecklar
author_rank: Regular Contributor
timestamp: December 03, 2014, 12:40:24 pm
content: Could you tell me what some of those applications would be that would require a 1X probe? Initially I plan to use the 2102A to better appreciate Arduino projects.

author: tggzzz
author_rank: Super Contributor
timestamp: December 03, 2014, 04:55:49 pm
content: Quote from: Ecklar on December 03, 2014, 12:40:24 pmAny application in which you need to measure small voltages (mV, not V). Classic examples are audio circuits and mechatronics.For digital signals you almost always need *10. To see risetimes <5ns (pulsewidth irrelevant), you need low impedance Z0 probes - which you can make yourself.

author: AG6QR
author_rank: Frequent Contributor
timestamp: December 03, 2014, 05:41:50 pm
content: Quote from: Ecklar on December 03, 2014, 12:40:24 pmtggzzz has covered it; when you need to measure the lowest voltages. A x1 probe can measure voltages at 1/10 the level of a x10 probe. The downside of x1 is that it loads the circuit more, and it has a much reduced bandwidth, typically in the neighborhood of 5MHz or so, even on a nice 200 MHz scope. The bandwidth issue is why x10 should usually be the default unless you just can't turn up the vertical gain enough to see the signal well at x10.If you want passive x1 probes, the Rigol RP2200 ones are available for around $33.00 apiece from multiple sources. There are other branded probes available, as well. If you already had fixed x10 probes, it's unlikely you'd need more than one switchable probe at a time (in fact it's not THAT likely you'd need one at all).Personally, I've got switchable probes, and I'd prefer fixed x10 probes, to eliminate the point of failure. The switch introduces two possible points of failure: mechanical failure of the switch, and human failure to check and set the switch properly. So far, I've only experienced the latter...