The UL listing has almost nothing to do with product function. mainly that it will not catch fire of harm the operator.jasonallenh said:I want one of these, kit, assembled, whatever... Regardless of UL listing. Not sure what good that would do anyway, considering the standard (UL listed) commercial tester does not work.
The cheap 3 lamp tester requires a look up table to interpret the results. Mine keeps it simple,,, Green is always good (line is hot as it should be), red is always bad (ground is hot and can kill you), and yellow is caution but won't kill you (neutral hot wrong but still safe in most gear). If you forget that legend and the screening has worn off the tester, just think about what you do if you come to stop light. If it's green you are Ok to go, if red not OK and you stop.Audio1Man said:Hi John
I think that your tester is very elegant. I do think that it may need another feature. Not all user (consumers) read and will understand the LED matrix. You may consider adding a FLASHING ERROR INDICATOR or ? for non teckies.
Great design Duke
Yup I considered putting lower voltage parts in series. Logically the breakdown mode from high voltage should force them to share equally not to mention the inherent resistive voltage divider so it "should work". In fact I may have done some measurements at 500V that confirmed it works. I also considered using a much larger part (1W) as a cheaper way to get the rated voltage, but as I ran out of PCB real estate I abandoned the even larger or even more components approach. I could realize the 500V I needed with single 1206 parts...Audio1Man said:Hi John
The 0805 parts are rated typ 350 volts. I use two in series and keep the voltage below 250 volt each. Routed PCB or holes do help.
Microphone and switching PS have similar problem with leakage. Your learning process will always help you.
Duke
In my early thinking I was looking for a DC path to some earth ground to buffer, but we are surrounded by insulators and very slight conductors and fields, AC or DC (static). I have come to the mindset that my buffer doesn't work that way...PRR said:> For normal environments the human body is sitting at roughly 0V DC and 0V AC wrt the environment.
That's what I'm unsure of.
If we are on a dirt-slab, literal "earth" dominates the field almost everywhere.
If we are on a tall dry tower with knob-and-tube open 120V wiring, we may suspect an average 60V field. And I had suspected that a "normally wired room" might approach this point.
In my dining room I just tried a Fluke DMM, black to electric ground, red in my hand. Generally about 300mV AC. Down to 20mV if my finger brushes one side of an all-plastic 2-pin plug, 300mV other side.
So in ultra limited testing, the floating (rubber shoes on carpet on wood floor) body is "0V AC reference" for safety purposes. Part-volts are not dangerous.
I will not grant the "0V DC" in winter. We know full well (places with dry heat) that we can build spark-size static electric fields on our bodies. I don't think this is a primary safety issue on stage.
It is not very common but happens. Within the last year a cable technician was sent to the hospital while installing a cable box that was plugged into a RPBG mis-wired outlet that put 120VAC onto the chassis ground. He got shocked between the hot chassis on the cable box and the real ground from the cable wire.80hinhiding said:Great work John. How common are faults between gear that would cause a serious risk? I am a cautious person and appreciate safety.
I'm afraid it's too much of a niche product to justify the couple $10ks for agency approval to sell a $20 product.80hinhiding said:Hi John,
Thanks. I just read the information on your website as well. Sad story about the guitar player who died. I hadn't really thought about this before. You have something there with your device.
Adam
I need to expand on this but there is a lot you can do without my OD-1Whoops said:John this is some amazing work from your part,
I really dont understand how the cheap testers are used by supposedly qualified technicians and are legal to use or sell.
Thanks you so much for your efforts and for providing your work for free, I feel a bit sad that it is so expensive to turn this into a commercial product, specially when we know this should be the standard product available.
I've been looking for something like this for some time now.
I will try to build some for myself, I do a lot of live sound gigs and sometimes I encounter some random and weird places where you don't feel safe.
Will this circuit also work in 240V mains countries or just in 120V?
Would it be possible to adapt for Europeans?
Thanks
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