Non Contact Voltage Pen Tester Teardown

[@lumpyfishgravy]

Looks like a regular Chinese knock-off of the Fluke VoltAlert. (On the outside! The inside is nothing like it.) I'm not employed by Fluke, but I have designed a successful Pen Tester. My boring comments (about the tester): * I have examined the 74HC14 circuit (on another model) and it suffers from a number of problems, the worst of which is sensitivity to battery voltage. There is also a known sensitivity to static which means the thing can light up in your toolbox and flatten the batteries over time. * I would rather see the batteries not in contact with the bare PCB. In particular the protruding pins could work through the battery sleeving with enough vibration. And from the latter part of your video I can see this. * The end battery contact will probably deform in a realistic drop test. * The chain of resistors is probably to work round buying one 100M (or whatever) resistor, which is a lower volume part therefore more expensive. * The PCB isn't milled - it's stamped with a press tool, hence the visible stress marks. Once they've decided the tool, they won't change it unless economic. * Don't worry about the PCB thickness - there are no BGAs. The cheap button is also fine. * The resistor to LED clearance is also fine. In fact everything inside the enclosure is at the same low potential. User safety is entirely provided by the translucent end cap.

[@horacewonghy]

Mike Page I use 4017,it simple and chooch

[@zyxwvutsrqponmlkjihgfedcba0]

I like this better than token overweight condescending nerd.

[@pspkutube]

Ah! So this is why the unit I have is beeping all over the surface of my cubicle desk... It is sensitive to static!!! Interesting part is that if I touch the same desk with my other hand while scanning with the tool, then it stops beeping... but restarts as soon as I take off my hand...

[@tobyw9573]

WD40 is good for removing adhesive labels, starting ether works OK and will evaporate.

[@EvanChavez]

Anyway to modify the resistor (input) to detect DC like 12v? Perhaps a hall sensor. I'm thinking of an automotive use case.

[@heinz-57]

Mine quit working. I took it apart but couldn't find anything obvious wrong with it. Any ideas what I should check?

[@gunnyoorah1846]

great job dude....wow hardly any draw .... would a higher chip improve the circuit? deeman

[@legalsolutions07]

Have you looked at the difference in the low cost unit you examined and a name brand unit like Fluke, Greenlee, GB, Milwaukee etc.? The reason I'm asking is most of the ones I listed are made in China. I want to know if the name brand have the same components and are made with the same quality as the low cost one you show? No sense in paying more for a name brand unit if they are the same as the low cost no-name non contact testers. Also, what used to sense voltage? The test you made seemed very good in that it was not too sensitive. Some of the units I've used are too sensitive and go off as far as two inches away and therefore are not useful when using in a wired junction box.

[@joeyysossa4144]

Ive had one of those fr 4 years and it works fine...at least I havent gotten shocked yet.

[@Mr11223marc]

haha not surprised to find 74hc14 inside! This IC is an Schmitt not trigger logic CMOS ! The Gate is so sensitive..

[@das250250]

These connections are the worst possible . I have owned 10 of these over the years and every single one fails to make proper contact with the batteries and doesn't show voltage until you open them and wriggle battery. So you never feel 100% confident the unit is working . One way is to press the led flash to see if it comes on . The battery terminals flex due to the super thin boards and never apply enough pressure to the battery. The board needs to be thicker and a proper spring load for the battery used .

[@darkblue086]

A区G排？chinese online shopping ？

[@rhoodj]

I bought one of those cheap chinese time ago. every time I try to use it. The light works only when I press the button. after that nothing happen. How could you explain that?

[@peterowens290]

Your test at the end which revealed battery short potential problem, also showed how relatively stiff was the probe when inserted into the outlet slots. You had to exert some force & manipulation to get the probe in & out. Surely the conclusion is it won' be long before the probe breaks. I have the Fluke 2AC/200-1000 & it will illuminate when the probe is held close (but not actually in) to the outlet slots. Seems like a better option?

[@dcvaldez1993]

My contact voltage (Fluke) tester,lucks sensitivity,when tracking an electric cord,that I know is on,does not give any indication what so ever ?? Only works on CB, or sockets out lets,but is not a "cable friendly" chriature. ¿Can I increase the sensitivity?

[@fredflintstone4138]

that rear, asymmetric notch out of the pcb might be to assist in machine-identification or machine-alignment of the circuit board during population of board. Perhaps it identifies the board as a revised-board. mystery notch : )

[@abbtech]

Interesting idea, that is a good possibility.

[@lo2740]

no, definitely not, first for pick and place registration that we use fiducial marks, and typically they are on the panel, not on unitary PCBs (for this kind of cheap product with large size SMD). Also we would never rely on outline for registration, because the outline is not accurate, especially when it is a stamping. Anyway the stamping is done after pcb assembly.

[@diytatay4991]

hi, im wondering if this can be modified to detect ac wires on cement walls? maybe a coil for the antenna?

[@celotlcoatl]

Does anyone knows the voltage that passes through the LED on the tip?

[@akbaxb165]

I bought one for couple of dollars with free delivery. It did not come with any instructions, but I was fortunate to find your video. Thank you. The unit I bought does the basic job and does not appear to be overly sensitive.

[@tim62744]

Could be made a bit better for the price

[@kar15bigdog]

I have a southwirwe tester and I dont know how to take it apart

[@brucewayne-cave]

I enjoyed your teardown...! I was wanting to use this in a setting where I want to measure the 120 vac wires inside an appliance. However I want to keep the batteries and all the electronics far outside the appliance. Do you think I could simply extend the 1M resistor off the board about 4ft, and still get a reading? Or would that distance compromise the calibration?

[@chinmoy1955]

Weird question...are you an engineer? This device is already very sensitive to electric field pickup, and you want a 4 ft extension??

[@Ni5ei]

The bare button contacts aren't too great but the battery having its sleeve being +1.5V is the real design flaw in this video. There are many devices (flashlights in particular) that use the casing as ground. Terrible design for a battery!

[@lo2740]

well, pretty much all AA and AAA batteries are like that, and they are all insulated with a relatively thick plastic layer too, of course if you poke in the layer with a mutlimeter probe you are going to reach the metal casing, but in normal operation it doesnt append.

[@freddypina6593]

No apaga la alarma el detector

[@mayorart1]

This one's JUNK!!!

[@nickward5190]

I got this cheap one to and I got the fluce as well and I did fide out it didn't hold up as it packet up but I only payed 2.99 UK pounds and the fluce was a lot better and it is better made and I payed for the fluce 25 UK pounds and to today I'm still useing the fluce so I would say it's a fake the cheaper ones are I like to be safe the sorry to be honest. But great review

[@vassallo604]

Fluke

[@renweb1332]

:-)

[@fastenergysolution1300]

how much price please

[@Rollmops94]

Schmutz?! :))

[@orange70383]

These Fluke prox testers are useless, ok here's a typical situation, you open a 4-square box with 3 277/480v circuits in it and you're wanting to see if one particular circuit is hot, so you separate the wires best you can, grab your Fluke tester and it lights up 6 inches away from the box making it impossible to check the circuit in question. Meaning you cannot separate the wires far enough apart to where the tester will not pickup the em field coming off the other circuits. So now you're pissed because you climbed up a 12 foot ladder and the guy you're working with says well is it hot or not and you reply I have no idea because it seems I bought a p.o.s. hot stick. Plus there's no sensitivity adjustment on the tool unless of course you feel like wasting an afternoon playing around with different component values trying to get the sensitivity right and you happen skilled in smt soldering.

[@abbtech]

I agree but often you just want to make sure everything is dead in the JB before you start ripping into it. For that application they are great.

[@lazyeejay]

I love the internet and I love KZbin, I have exactly this pen and dropped it. When I looked at the circuit board I saw the sensor wire and thought it had come away from the board. I figured I'd google voltage pen circuit board and your video came up and answered my question. Now my pen is working again. Thank you so much, don't ever think these kind of videos are of no use because there is always someone like me looking for the answers to the most obscure questions. Thank you👍👍👍👍