Products > Test Equipment
Is NON-CONTACT VOLTAGE feature worth it?
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5U4GB:

--- Quote from: floobydust on March 15, 2024, 02:57:35 am ---I got a cheap NCV probe from Aliexpress I think it was $1 possibly a Fluke knockoff. Hmmm it didn't work very good at all, poor sensitivity. Took it apart, the problem is the probe tip was missing the metal flag and somebody put a resistor lead in place. It uses a 74HC14 and very high Z input impedance 12x22MEG (264MEG) to GND. Works great now.

--- End quote ---

I use a Klein NCVT3 (watch out for the gimmicky ones they added later like the -4 and -5) which is pretty decent and fixes some of the problems very early versions had, e.g. not having an it's-switched-on indicator so you wouldn't know whether it wasn't detecting anything or wasn't even on, it also has an LED bargraph showing the strength of the field and from teardowns is a lot better engineered than a lot of the few-dollars Aliexpress ones.

The most important thing to remember about them though is to always check on a live circuit first before using it to test whatever you're testing.  To be extra safe, bracket the test, so live circuit, circuit being tested, live circuit again.
jonpaul:
Simon: A VOM/DVM is not as useful  as a separate NC probe a
For mains and HV  work we use the excellent  non contact Fluke probes 1AC II 1000V https://www.fluke.com/en-us/product/electrical-testing/basic-testers/fluke-1ac-ii

Best handheld overall DVM is Fluke 87: The 187, 287 are not as reliable and the screens have a questionable uggedness .


 I bought Fluke 87  V  $175 LN w/ test leads and case. Very satisfied. Assembled in USA.
CAT III 600V CAT IV 1000V.

Cheers!

Jon
shapirus:

--- Quote from: floobydust on March 15, 2024, 02:57:35 am ---I got a cheap NCV probe from Aliexpress I think it was $1 possibly a Fluke knockoff. Hmmm it didn't work very good at all, poor sensitivity. Took it apart, the problem is the probe tip was missing the metal flag and somebody put a resistor lead in place. It uses a 74HC14 and very high Z input impedance 12x22MEG (264MEG) to GND. Works great now.

--- End quote ---
An NCV probe can be relatively easily DIY'ed btw, with any level of sensitivity desired (and/or with an adjustable sensitivity), and that will very likely end up being better than most of dedicated or DMM NCV probes. I think it may even make sense to add a 50/60 Hz band pass filter to only trigger on the mains-induced field. The only problem is finding a suitable case, but if you can find a sufficiently thick pen, it'll probably do. It's going to be an interesting project to design a PCB that fits there just right.
5U4GB:
Or get the cheapest Ali one that looks about right, rip the guts out, and replace it with your own circuit.
shapirus:

--- Quote from: 5U4GB on March 15, 2024, 10:14:29 am ---Or get the cheapest Ali one that looks about right, rip the guts out, and replace it with your own circuit.

--- End quote ---
Lol yes, may very well end up being cheaper than a pen, let alone a dedicated DIY case.
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