From: Paul McGill <mcgill@mbari.org>
Subject: Re: GFI board
Date: November 6, 2017 at 9:35:32 AM PST
To: DJ Osborne <djo@mbari.org>

Whoa, you’re right. That part was in stock last week, but it looks like someone bought the world’s supply of them. My second choice, the 5.6 kohm is also out of stock. However, you can get 4.7 kohm from quite a few places:

< https://www.findchips.com/search/766163472GP>

They’ll dissipate 120 mW, which is still well below the rating of 240 mW.

Yes, there are different sizes of SOIC packages, but I think this particular part only comes in one size. I checked Digi-key’s listed package width for this part and it matches the part on the GF board.

Hope that helps,
Paul

On Nov 6, 2017, at 8:08 AM, DJ Osborne <djo@mbari.org> wrote:
Hey Paul,
I thought I was set, but mouser just backordered this part with no delivery date set.
I am going to need to find someone else that has this in stock.
 
Seems trivial but I see there are three different widths to SOIC 16?
 
Probably need to dig out the micrometer, his pdf isn’t that specific it seems.
Thanks,
dj
 
From: Paul McGill [mailto:mcgill@mbari.org] 
Sent: Thursday, October 26, 2017 4:50 PM
To: DJ Osborne
Cc: Craig Dawe; Mike Burczynski; David French; Rich Schramm; Jose Rosal
Subject: Re: GFI board
 
DJ,
 
Wow, what a difference from the bad schematic copy I’ve been squinting at for years!
 
If you bypass the 5 V regulator, you should also raise the value of the pullup resistor network R10. With 24 V through 1 kohm, you’d be dissipating 0.576 W per resistor when an output bit is low, but those resistor packs are rated for only 0.24 W per resistor. I’d bump it up to, say, 5.1 kohm with this part:
 
<https://www.mouser.com/ProductDetail/CTS-Electronic-Components/766163512GP>
 
That knocks the power down to 0.113 W per resistor.
 
The output transistors on the optocouplers U7 and U8 are rated to 40 V, so they should be fine. C22 is rated at 50 V, so you should be okay there too.
 
Cheers,
Paul

On Oct 26, 2017, at 2:10 PM, DJ Osborne <djo@mbari.org> wrote:
 
Hi,
For your files/records… 
A readable version of our DTEC ground fault board.
 
This will be handy when we replace/test/upgrade the GF board/system in the control can.
 
The new board finally arrived from DTEC after it was lost in shipping….
 
We need to make the modifications to make it compatible with our 24 volt system.
 
I believe all that has been done is remove the 5 volt regulator and then short the input to the output so the 24 V passes thru.
 
Can anyone comment that has performed the modification?  I suppose it may have been Jose, but I doubt he will remember exactly what he was requested to do to it.
 
Thanks,
dj
 
From: Joshua David Tetarenko [mailto:tetarenko.josh@gmail.com] 
Sent: Tuesday, October 24, 2017 7:56 PM
To: DJ Osborne
Subject: Re: GFI board
 
Hey DJ,
 
No worries, here it is. If you go to www.dtec.ca there is a description of the board if you click on “Ground Fault and Water Alarm Board” on the lefthand side of the homepage.
 
Thanks,
Josh

On Oct 24, 2017, at 11:36 AM, DJ Osborne <djo@mbari.org> wrote:
 
Hey Josh,
Do you have a decent electronic copy of the drawing for the board?
The old ones we have are really terrible.  The copy you sent would be by far the best copy we have but it would be great to get it electronically.
Thanks,
dj
 
From: DJ Osborne [mailto:djo@mbari.org] 
Sent: Tuesday, October 24, 2017 10:58 AM
To: 'Joshua David Tetarenko'
Cc: Craig Dawe
Subject: GFI board
 
Hey Josh,
Your second board showed up today as promised…
But the surprise was that BOTH boards arrived.
Yes, I now have two boards here in stock.
Guess they found it… 
Craig and I can have a conversation regarding if we want to keep it or not – will let you know.
Thanks,
dj
<GFIWATER-24VDC Schematic.pdf><Untitled attachment 00414.htm>