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Author Topic: brain storm an optimal human safety system for back line  (Read 101858 times)

John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #150 on: February 08, 2015, 01:02:01 pm »

So you think it's a NCVT built into a 3-light tester? I've been asking for that sort of thing for a long time.

the internet ate my first answer so I'll keep this brief... I just added some neon bulbs to my current parts order. I suspect I can make a simple outlet checker with neon lamps and a touch contact that could detect reversed polarity, and open ground. But I need to build one to confirm... the neon lamps draw about 1 mA so should not be much of a shock hazard.

======
I am rethinking the value of the stinger cap with GFCI approach. The typical class A(?) GFCI is 5 mA +/-1 mA. I just confirmed on the bench that my stinger GFCI with only 0.1uF does not trip (4.5mA)... I am leaning toward 0.15 uF for enough current to trip the GFCI but still low enough that humans won't get stuck to it.  My parts vendor does not have any 0.15uF Y caps in stock, but they do make them.

Still evolving...

JR

PS: for more adventures in cheap house wiring, I just figure that if I convert my 2 wire outlet to three wire where both my washing machine and dishwasher plug in, a hot chassis fault in one will energize the chassis of the other.  :o :o So I definitely need to rig up a ground wire from the fuse box a few feet away.   
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Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Peter Morris

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Re: brain storm an optimal human safety system for back line
« Reply #151 on: February 09, 2015, 03:41:44 am »

the internet ate my first answer so I'll keep this brief... I just added some neon bulbs to my current parts order. I suspect I can make a simple outlet checker with neon lamps and a touch contact that could detect reversed polarity, and open ground. But I need to build one to confirm... the neon lamps draw about 1 mA so should not be much of a shock hazard.

======
I am rethinking the value of the stinger cap with GFCI approach. The typical class A(?) GFCI is 5 mA +/-1 mA. I just confirmed on the bench that my stinger GFCI with only 0.1uF does not trip (4.5mA)... I am leaning toward 0.15 uF for enough current to trip the GFCI but still low enough that humans won't get stuck to it.  My parts vendor does not have any 0.15uF Y caps in stock, but they do make them.

Still evolving...

JR

PS: for more adventures in cheap house wiring, I just figure that if I convert my 2 wire outlet to three wire where both my washing machine and dishwasher plug in, a hot chassis fault in one will energize the chassis of the other.  :o :o So I definitely need to rig up a ground wire from the fuse box a few feet away.   

Yes you can ... can't find the one I had; but FWIW I always ran something like this [below] in a spare socket in my racks and used RCD protection.  That's almost a manual version of what you are after.

Now we use this http://www.jands.com.au/brands/jands/power-distribution/PDS6RII
« Last Edit: February 09, 2015, 07:01:32 am by Peter Morris »
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #152 on: February 09, 2015, 09:42:42 am »

Yes you can ... can't find the one I had; but FWIW I always ran something like this [below] in a spare socket in my racks and used RCD protection.  That's almost a manual version of what you are after.

Now we use this http://www.jands.com.au/brands/jands/power-distribution/PDS6RII
Does that tester catch RPBG?

Perhaps I wasn't clear... of course neon lamps can confirm power present, I am talking about using a simple neon lamp as a NCVT to probe neutral and ground for line voltage, by using the human body as the other contact for the bulb. A normal neon lamp draws less than 1 mA and even the high brightness that I found are something like 1.2mA so not much of a shock hazard, but I need to see if it works. Since the lamp will light at about 60V I could probably put enough of a resistor in series that even a shorted lamp would not make you stick to it (10-15 mA).

JR
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Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #153 on: February 09, 2015, 01:11:46 pm »

I finished modifying my stinger GFCI test bed. I had to jury rig up a 0.15uF from 3 x 0.1uF but now I have 160V caps with enough current draw to trip the GFCI. Since I don't have a grounded outlet in my house I had to rig up a bootleg outlet to test it.. It appears I have reversed polarity on my workbench outlet, so I had to wire up the test outlet RPBG to get the bootleg ground on the neutral...   Testing a short to ground with the stinger cap in series with ground tripped the GFCI so now I feel like it is safe enough to continue testing.

6.7 mA is enough current to be felt as a shock but is well below the current that causes us to stick to it or experience serious injury...   

0.15uF should be even better at shielding than the typical .047 stinger cap used in old legacy amps. So I am pretty confident this will work.

Only difference is we should source some proper 0.15uF 300-400V Y caps. (The "y" rating insures that it will not fail as a short circuit for human safety on that application.)

JR

Note: if-when I make my electronic fuse that can trip much lower than the GFCI 4-6 mA I may add a path to trip the GFCI  open whenever the electronic fuse trips.
« Last Edit: February 09, 2015, 01:38:10 pm by John Roberts {JR} »
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Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Tim McCulloch

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Re: brain storm an optimal human safety system for back line
« Reply #154 on: February 09, 2015, 03:32:20 pm »

The misanthrope in me still thinks it more amusing to electrocute musicians.

/snark, satire, sarcasm, other literary devices

The last 2 weeks has taken me from curmudgeonliness to misanthropy - I'm learning to hate humanity one person at a time - and for some reason the persons of my disdain all seemed to have "musical" instruments in their hands.
« Last Edit: February 09, 2015, 03:47:57 pm by Tim McCulloch »
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Stephen Swaffer

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Re: brain storm an optimal human safety system for back line
« Reply #155 on: February 09, 2015, 05:26:41 pm »

Perhaps you could convince JR to change the switch to a remote controlled switch and adding a 3rd position tied to a charged cap giving a charged similar to an electric fencer so a 3 pos switch-stinger cap * lifted ground * sting.  Might give a little satisfaction.  I know I don't feel real bad when, after putting the horses back in the pasture, I see their reaction when they test the fence.
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Steve Swaffer

John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #156 on: February 09, 2015, 05:41:41 pm »

I'm not sure I should feed this veer... I'm trying to save musicians, but it's OK to see them jump and dance (St. Vitus) a little when they deserve to.  ;D

It seems a floating ground system at FOH, with a Van de Graf generator charging up the console chassis to thousands of volts, might do something. You may need to watch yourself when mixing but you could send some harmless voltage to the musician via mic ground. Of course you might blow up the console too...

JR

 
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Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Tim McCulloch

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Re: brain storm an optimal human safety system for back line
« Reply #157 on: February 09, 2015, 06:38:06 pm »

I'm not sure I should feed this veer... I'm trying to save musicians, but it's OK to see them jump and dance (St. Vitus) a little when they deserve to.  ;D

It seems a floating ground system at FOH, with a Van de Graf generator charging up the console chassis to thousands of volts, might do something. You may need to watch yourself when mixing but you could send some harmless voltage to the musician via mic ground. Of course you might blow up the console too...

JR

 

Yeah, there's a down side to the Van de Graf...

I'll continue to make sure our AC service is all tight and proper.  While it might be fun to watch the puppets dance, I don't want it to happen with our string...
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Peter Morris

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Re: brain storm an optimal human safety system for back line
« Reply #158 on: February 09, 2015, 11:16:59 pm »

I'm not sure I should feed this veer... I'm trying to save musicians, but it's OK to see them jump and dance (St. Vitus) a little when they deserve to.  ;D

It seems a floating ground system at FOH, with a Van de Graf generator charging up the console chassis to thousands of volts, might do something. You may need to watch yourself when mixing but you could send some harmless voltage to the musician via mic ground. Of course you might blow up the console too...

JR

 

Hi JR,

For some reason Van de Graf generator made me think of SIA at the Grammys. https://www.youtube.com/watch?v=jZEFuCxD7BE

She is actually from my home town and was in a band called Crisp(!) that I seem to remember providing production for Ö. Absolute talent!

...anyway regarding my above post, I think I was a little too cryptic.  My tester used neonís with a resistor just as you described and the human body as the earth.

The picture I posted above is different, its a the 110 volt version I what I used with my rig. It would detect missing neutral, reverse polarity, no earth, and no power etc. Logically integrating these functions with an RCD will get you close for not many $$$
 
« Last Edit: February 10, 2015, 02:56:20 am by Peter Morris »
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Peter Morris

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Re: brain storm an optimal human safety system for back line
« Reply #159 on: February 10, 2015, 02:52:13 am »

oops double post
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Re: brain storm an optimal human safety system for back line
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