ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 ... 42 43 [44] 45 46 ... 55   Go Down

Author Topic: brain storm an optimal human safety system for back line  (Read 102518 times)

Mark Cadwallader

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1272
  • Helena, Montana USA
Re: brain storm an optimal human safety system for back line
« Reply #430 on: January 25, 2016, 09:12:20 pm »

My guess is that an endmill in a drill press would work a lot better than a drill bit.

Yes, and use a 1" collet to hold the PCB firmly and accurately located. The end mill does not need to be a centercutting design.

Edit:  never mind, if you don't have a drill press (or milling machine).
Logged
"Good tools are expensive, but cheap tools are damned expensive."

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16379
  • Hickory, Mississippi, USA
    • Resotune
Re: brain storm an optimal human safety system for back line
« Reply #431 on: January 28, 2016, 03:11:58 pm »

I am able to open up the undersized hole with roper whitney punch, and finish with dremel...

Right now I'm wrestling with trying to make it work with GFCI... outlet wired RPBG, but this probably depends on where the ground is bootlegged from, from output it should be all good as far as GFCI is concerned. 

another step forward.

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

Stephen Kirby

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3006
Re: brain storm an optimal human safety system for back line
« Reply #432 on: January 28, 2016, 06:15:27 pm »

Yep, the Dremel is the ticket.  PCB drills are very high speed carbide bits with very shallow points, almost like small end mills.  A PCB drill bit in a Dremel is a really handy tool to have for carving up any fiber reinforced plastics.
Logged

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16379
  • Hickory, Mississippi, USA
    • Resotune
Re: brain storm an optimal human safety system for back line
« Reply #433 on: February 04, 2016, 07:10:16 pm »

Another step forward....

Since I changed to GFCI outlet in my RPBG test fixture, touching the test probe contact was tripping the GFCI from >5mA diverted to ground. (My bootleg ground to the input side of the GFCI) means the ground indication current is outside the GFCI loop.

I want my tester to still accurately report RPBG without tripping any GFCI.

My first attempt was a fail... I flipped the polarity of the ground present LED to be opposite and not in parallel with the ground fault LED. My approach worked to get the current down, but caused a new problem, if the ground was floating the two ground LEDs conducted through each other so got two false indications.   :(

Suck-cess....  I reduced the current in both the red ground hot fault LED, and the normal ground LED still in parallel to keep the total current less than the trip threshold.

I still need to test my 240V (added neon lamp) feature.  But this is getting really damn close to done. Nothing left to fix...:-)

After that maybe 240V feature is tested I get to fire up my 500v ps to test for leakage.  :o :o :o

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

Josh Rawls

  • Full Member
  • ***
  • Offline Offline
  • Posts: 184
Re: brain storm an optimal human safety system for back line
« Reply #434 on: February 04, 2016, 08:43:42 pm »

Another step forward....

Since I changed to GFCI outlet in my RPBG test fixture, touching the test probe contact was tripping the GFCI from >5mA diverted to ground. (My bootleg ground to the input side of the GFCI) means the ground indication current is outside the GFCI loop.

I want my tester to still accurately report RPBG without tripping any GFCI.

My first attempt was a fail... I flipped the polarity of the ground present LED to be opposite and not in parallel with the ground fault LED. My approach worked to get the current down, but caused a new problem, if the ground was floating the two ground LEDs conducted through each other so got two false indications.   :(

Suck-cess....  I reduced the current in both the red ground hot fault LED, and the normal ground LED still in parallel to keep the total current less than the trip threshold.

I still need to test my 240V (added neon lamp) feature.  But this is getting really damn close to done. Nothing left to fix...:-)

After that maybe 240V feature is tested I get to fire up my 500v ps to test for leakage.  :o :o :o

JR   

I'm excited to see your progress. When these are on the market I will order a few of them. For now I have trained all my DJs how to test an outlet with a meter and a NCVD.
Logged
Josh Rawls

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3355
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: brain storm an optimal human safety system for back line
« Reply #435 on: February 05, 2016, 11:21:58 am »

I want my tester to still accurately report RPBG without tripping any GFCI.

Report from the field. Call me to discuss details, but the prototype does seem to 100% indicate on an RPBG, and will find an elevated ground as low as 75 volts with me being completely isolated from earth. If I'm physically high-z grounded by laying my hand on a painted metal surface, it will indicate an elevated ground as low as 30 volts. Don't worry, I'm being careful with this.

No GFCI's were tripped during these experiments...  ;)
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16379
  • Hickory, Mississippi, USA
    • Resotune
Re: brain storm an optimal human safety system for back line
« Reply #436 on: February 05, 2016, 12:54:53 pm »

Report from the field. Call me to discuss details, but the prototype does seem to 100% indicate on an RPBG, and will find an elevated ground as low as 75 volts with me being completely isolated from earth. If I'm physically high-z grounded by laying my hand on a painted metal surface, it will indicate an elevated ground as low as 30 volts. Don't worry, I'm being careful with this.

No GFCI's were tripped during these experiments...  ;)
The input resistance is 100 MegOhm so no hazard.

One question I have pondered is what happens if you are standing inside a hot-skin RV? It seems like then the local ground reference voltage would be 120VAC.  :o :o  Of course I don't expect you to ever get inside a hot skin RV to find out (I sure wouldn't).

Plugging the OD-1 into one of the RV's external outlets would reveal the hazard without exposing the human (unless the outlet has a grounded metal outlet cover you have to open that is energized). NCVT is the play before approaching any RV.

 thanx for the feedback...

JR

PS: Mike's OD-1 prototype is not using the latest low current ground LED resistors so would trip my GFCI/RPBG test fixture. If the ground bootleg is performed on the output side of the GFCI the ground current stays inside the detection loop so won't trip. RPBG are bad... :o 



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

Jonathan Johnson

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2997
  • Southwest Washington (state, not DC)
Re: brain storm an optimal human safety system for back line
« Reply #437 on: February 05, 2016, 01:57:27 pm »

One question I have pondered is what happens if you are standing inside a hot-skin RV? It seems like then the local ground reference voltage would be 120VAC.  :o :o  Of course I don't expect you to ever get inside a hot skin RV to find out (I sure wouldn't).

Well, if it's a Airstream (stainless steel skin) parked next to another Airstream trailer, also with a hot skin but connected to the other pole of the 240V circuit, then they'd both be electromagnets of opposite polarity. Since opposites attract, they'd sidle up to each other through magnetism, short out, and melt down. You're right, I wouldn't want to be standing in one, either. ;-)

Of course, that wouldn't happen. But we can imagine, can't we?

It's not wise to step into an RV with a hot skin condition, as becoming part of a circuit between hot and ground generally does not bode well for that person. However, if you step inside to do measurements and then the hot chassis condition is applied, you *should* be safe as you will be at the same potential as the local ground reference inside the trailer.
Logged
Stop confusing the issue with facts and logic!

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3355
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: brain storm an optimal human safety system for back line
« Reply #438 on: February 05, 2016, 02:29:46 pm »

It's not wise to step into an RV with a hot skin condition, as becoming part of a circuit between hot and ground generally does not bode well for that person. However, if you step inside to do measurements and then the hot chassis condition is applied, you *should* be safe as you will be at the same potential as the local ground reference inside the trailer.
Uhmmmm.... Here I am doing exactly that in a video. You can see me standing on the steps of an RV electrified with a hot-skin potential of 120-volts AC using a NCVT to test for a hot ground. Starts around 4:45 or so in the video.

https://www.youtube.com/watch?v=Y8h64X33aKg&list=PLbNmdE7sBb0dt0zyv6ULMeacIcqvxwuNO

Yeah, I have too much fun with this...
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Frank DeWitt

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 995
    • LBP DI Box
Re: brain storm an optimal human safety system for back line
« Reply #439 on: February 05, 2016, 02:56:17 pm »

Well, if it's a Airstream (stainless steel skin) parked next to another Airstream trailer, also with a hot skin but connected to the other pole of the 240V circuit, then they'd both be electromagnets of opposite polarity. Since opposites attract, they'd sidle up to each other through magnetism, short out, and melt down. You're right, I wouldn't want to be standing in one, either. ;-)


I think they would slide up to one another and the next thing you know there is a little teardrop trailer.
Logged
Not to Code

ProSoundWeb Community

Re: brain storm an optimal human safety system for back line
« Reply #439 on: February 05, 2016, 02:56:17 pm »


Pages: 1 ... 42 43 [44] 45 46 ... 55   Go Up
 



Page created in 0.113 seconds with 25 queries.