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Author Topic: brain storm an optimal human safety system for back line  (Read 96186 times)

Scott Holtzman

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Re: brain storm an optimal human safety system for back line
« Reply #210 on: May 05, 2015, 11:19:33 pm »

[veer]
The wood inside my kitchen counter tops hasn't been green for half a century. I still do not understand where the resistance path between the counter trim and metal sink is but I measure about 100k there. Just for chuckles I measured capacitance and got around 0.4 nF. (Perhaps 50 years of smutz under the counter.)

My (food) mixer measures 1.2 nF between one leg of the line cord and ground. This capacitance is asymmetrical, only .2 nF on other leg, so outlet polarity could matter for conducted leakage.

I really need to re-wire my house with grounded outlet wiring but that's way too much work...   [/veer]

JR

Since you bust on American English what is smutz?  Is that a collection of old porn?  Shmutz is yiddish slang for anything messy.  IE:  I got shmutz on my shirt.  It can also be used as a verb IE: I shmutzed up the tablecloth.  Short for shmutzik that is dirt.

Don't get me wrong I am not all fershlugina over this.  Fershtay?

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Scott AKA "Skyking" Holtzman
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #211 on: May 06, 2015, 10:09:45 am »

Since you bust on American English what is smutz?  Is that a collection of old porn?  Shmutz is yiddish slang for anything messy.  IE:  I got shmutz on my shirt.  It can also be used as a verb IE: I shmutzed up the tablecloth.  Short for shmutzik that is dirt.

Don't get me wrong I am not all fershlugina over this.  Fershtay?

Yes I meant shmutz but I don't spell yiddish or english very well. I was referring to food debris and dirt that gets trapped around the cracks and edges of counter edge and top surfaces... I'm sure there is decades of shmutz trapped behind the metal trim.

I suspect shmutz could be somewhat conductive due to moisture content.

JR
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Scott Holtzman

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Re: brain storm an optimal human safety system for back line
« Reply #212 on: May 06, 2015, 09:53:01 pm »

and I was just being silly sitting on the couch recovering from a dental appointment that started with "do you really need nova Caine I am running behind" explaining that since I already had a root canal it would hurt. 
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Tim McCulloch

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Re: brain storm an optimal human safety system for back line
« Reply #213 on: May 06, 2015, 10:06:58 pm »

and I was just being silly sitting on the couch recovering from a dental appointment that started with "do you really need nova Caine I am running behind" explaining that since I already had a root canal it would hurt.

A former colleague told me of a trip to the dentist - the patient was in the chair and the doc said "open, please".  The patient reached back, grasped the dentist's scrotum and asked "Doc, we're not going to hurt each other, are we?"
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #214 on: May 06, 2015, 10:15:10 pm »

and I was just being silly sitting on the couch recovering from a dental appointment that started with "do you really need nova Caine I am running behind" explaining that since I already had a root canal it would hurt.
wouldn't (?)

The root canal has removed the damaged nerve tissue from the tooth. Root canals are not fun. In theory no nerve means no pain. But it seems it always hurts some. If not during the dental visit, later when you get the bill. 

JR   
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Jonathan Johnson

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Re: brain storm an optimal human safety system for back line
« Reply #215 on: May 06, 2015, 11:05:05 pm »

wouldn't (?)

The root canal has removed the damaged nerve tissue from the tooth. Root canals are not fun. In theory no nerve means no pain. But it seems it always hurts some. If not during the dental visit, later when you get the bill. 

JR

To veer this back on topic (sort of), the most awful pain you can experience without actual injury is when the dentist tags a nerve with the needle and you feel a full-body neural electrical overload. What I would've given to have a GFCI in my nervous system...

Talk about a "brain storm." I'd call it about a 12 on the pain scale... a scale which only goes to 10.
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Mike Sokol

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Re: brain storm an optimal human safety system for back line
« Reply #216 on: May 07, 2015, 08:22:57 am »

To veer this back on topic (sort of), the most awful pain you can experience without actual injury is when the dentist tags a nerve with the needle and you feel a full-body neural electrical overload. What I would've given to have a GFCI in my nervous system...

You can get a smaller version of this by chomping down on a ball of aluminum foil. I think there's some battery action going on between the dissimilar metals of your fillings and the aluminum, with your saliva serving as the electrolyte. But it's been a long time since I tried that. 

OK... Back OT. I'm pretty sure you can't fit a GFCI in your teeth.
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #217 on: May 19, 2015, 08:41:21 pm »

OK, back in topic... I finally started melting solder on this project.

Bad news first, I figured out that my preliminary design was short several parts. To make it ignore reverse polarity outlets, I needed to use triac switches on both the line and neutral inputs .... OK 2 triacs, and 2 opto drivers. I got the touch switch working but need to tweak the sensitivity... right now it turns on for both correct polarity and reverse polarity too (not good).

The good news is the relay coil powered from the output side of the GFCI latches on, from the touch switch momentary power,  and opens power and ground if the GFCI opens.

Tomorrow I will start tweaking on the touch switch sensitivity. It needs to only work for correct polarity power or there is no need for it.

So good progress...so far, but more bench work to go. 

JR

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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #218 on: May 20, 2015, 01:23:48 pm »

More progress... It turns out I had a bench issue. I know that my bench power is both ungrounded and reverse polarity. I rigged up a loose outlet as an adapter with bootleg ground, to test GFCI before. Apparently I didn't reverse the polarity in this adapter so what I thought was correct polarity, was still reverse polarity in both test modes.

Now I am getting correct operation from my touch switch.. i.e. touch contact turns on and latches the GFCI outlet on for correct polarity wired outlet. If outlet is reverse polarity touch switch does not work. It will occasionally still trigger from the touch circuit with reverse polarity, perhaps once every 25 touches or so,  but I can probably harden for that. 

So far I have proved out a smart GFCI that refuses to turn on for miswired outlet, "and" opens the ground when GFCI trips. Already pretty cool, but more to go.

Remaining to be tested is can I add a secondary GFCI trip circuit from measuring voltage/current flowing in the ground and use that to trip the GFCI and open the ground path too.  I plan to use the same opto-osolator I am using for the triacs. worst case 5 mA for rated output, but I expect it to work at even lower trip current. Note: this ground current threshold is separate from and independent of the GFCI. I intentionally imbalance the GFCI to force it to trip when I sense current in the ground that could be coming from anywhere.

JR

PS: I tested using the not yet powered up output side of the GFCI as an alternate touch input to hopefully turn on the outlet automatically when power is applied but it works too well... turning on for reverse polarity too. I may soak this in beer and revisit this later. I don't care for having to reset this every time power blinks off.   


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Tim McCulloch

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Re: brain storm an optimal human safety system for back line
« Reply #219 on: May 20, 2015, 01:52:19 pm »

I think it more humane for music and art to simply let the AC flow.... and if some numb-nuts muso wants to run dangerous equipment that results in his death or injury, that's his personal decision.  Kind of the libertarian approach to safety...  /satire, sort of but not really

Tim "still cynical after all these years" Mc
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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
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