Reinventing the neon test screwdriver

I like the LED version and brightness is definitely an advantage here, but neon being the simplest, is probably more reliable.

Also a good demonstration of why we have "one hand in a pocket rule" if you must work with live voltage.

Clive, don't forget that a neon has a 50v strike voltage. So with a neon, it'll only light when above 50v. With 3 leds, it'll light up at any voltage above around 10v. Yiu need a zener in there... 😀

Interesting. I'd like to see some measurements for both versions. Actual current for a start, if you've got a meter sensitive enough, both grounded and non-grounded. Also voltage drop across the screwdriver and across your body when grounded. I've a feeling the neon drops a higher voltage than the LEDs, so would be considered "safer". Using ordinary 3 or 5mm LEDs instead of the tape might give better all round vision, although the neon ones tend to have a little "lens" over them so you can see the tiny glow better.

One of the only applications I can see for those insanely bright blue LED's.

Great work Clive. Thanks for the time an effort. Can see that a fair amount of time was put into it.

Yes, the problem with a series string of diodes is that they don't share reverse voltage equally or in any specified way since it depends on the leakage current vs reverse voltage curve. Your third option with three independent groups of LEDs looks more attractive.

As a rule, I've always found the neon hard to see unless you are working in a rather dark area. Your LED version is very easy to see.

Your implementation with the LED's is by far superior - and looks great as well. I'd happily buy and use one.

In re green LEDs being the most efficient: it's also the colour to which our eyes are most sensitive. I did an SYS project on this and having got the wrong answer during my interview I will never, never forget that the wavelength which appears brightest to human eyes is 555nm.

I just like how such things can glow when plugged in extension cord that has switch in off position. Feels like magic.

Very interesting 🧐 I like the LED version better than the Neon indicator.

I think the Neon lamps are safer and last forever in such application. The fact that diodes fail short is disconcerting. Neon lamps have two plates separated by gas, not much can go wrong there.

The thing to remember is that even with the good old Martindale tester you were still instructed to test it on a known live source before using it! Worth remembering if it is hardly ever used and gets damp/corroded in the bottom of an old tool bag and goes o/c! Common sense and a little electrical knowledge can go a long way!

Brilliant update and thanks for answering my previous question. Might look at making one.

Clever idea Clive - clearly the green LEDs appear much brighter.

Used to love proper neon screwdrivers, they're great for detecting the presence of high frequency AC, you just hold the body of it near to the source and if it's energised the neon glows. Dead handy for working on old CRT tellies and radio gear because it takes a good whack of radiated energy to light it up..

Brilliant explanation Clive really enjoyed your version too 😊

The neon has a much higher threshold which could be useful. To duplicate the effect a couple of back to back zeners in the 68V range in series could be added.

Nice video there and interesting as well. I prefer the definite brightness of the LEDs as I have found on occasions it is difficult to tell if tge neon has lit up or if it is a reflection off something else. There will be the traditionalists out there that will prefer neon over anything as that is what they have used for the last 20 years but they fail to remember that before these testers we used apprentices to test for live wires, if they made a mig of tea afterwards it was safe to work, if you needed the plasterer to repair a human shaped hole in the wall it was still live 🤣 Obviously the last part is a joke but the traditionalists will still favour neon 👍