Ok, I feel like a total idiot...... :)

Genesis · 17th April 2006, 21:45

Ever have one of those days?

I got the R3 PC boards in while we were out of town. Was out Mousing around with my daughter. Anyway, on our return last night I had a look and set about to build up a couple so I can continue my integration.

Anyway, I built up a head board, no problems found. Inspection looked good, everything fits, etc.

Started on the CPU board and immediately saw a problem. I had foolishly laid a power trace under the voltage regulator chip.

Now this would not be a problem - if the trace hadn't been on the same layer as the chip! But it is, and the nasty part is that the "tab" that provides heat sink (and ground) runs all the way under the bottom. So - this would be a nice direct power to ground short.

Crap.

Needless to say that board didn't get built up last night...... this falls into the category of truly stupid mistakes, but heh, we all make 'em from time to time, right?

Oh well - Rev 3.000000001 anyone?

dantheman · 17th April 2006, 22:06

Quote: (Originally Posted by Genesis)

... I had foolishly laid a power trace under the voltage regulator chip...

I hate it when I do that ...

--dan
(who works at a level of abstraction above electrons)

steevke · 17th April 2006, 22:56

Try using a 'decent' PCB layout package (eagle e.g. which is free for small boards). A standard electrical rule check catches these errors without any problem.

Steven

Sutty · 17th April 2006, 23:05

Quote: (Originally Posted by steevke)

Try using a 'decent' PCB layout package (eagle e.g. which is free for small boards). A standard electrical rule check catches these errors without any problem.

Steven

Got a link to this?

Genesis · 17th April 2006, 23:07

Quote: (Originally Posted by steevke)

Try using a 'decent' PCB layout package (eagle e.g. which is free for small boards). A standard electrical rule check catches these errors without any problem.

Steven

Eagle is IMHO a royal pain in the butt.....

jdz · 17th April 2006, 23:51

Quote: (Originally Posted by Sutty)

Got a link to this?

Hi there..

start here... http://www.cadsoft.de/freeware.htm

Cheers, JDZ

Sutty · 18th April 2006, 00:01

Quote: (Originally Posted by jdz)

Hi there..

start here... http://www.cadsoft.de/freeware.htm

Cheers, JDZ

Thanks for that

Scuba_Vixen · 18th April 2006, 03:44

Quote: (Originally Posted by Genesis)

Ever have one of those days?

I got the R3 PC boards in while we were out of town. Was out Mousing around with my daughter. Anyway, on our return last night I had a look and set about to build up a couple so I can continue my integration.

Anyway, I built up a head board, no problems found. Inspection looked good, everything fits, etc.

Started on the CPU board and immediately saw a problem. I had foolishly laid a power trace under the voltage regulator chip.

Now this would not be a problem - if the trace hadn't been on the same layer as the chip! But it is, and the nasty part is that the "tab" that provides heat sink (and ground) runs all the way under the bottom. So - this would be a nice direct power to ground short.

Crap.

Needless to say that board didn't get built up last night...... this falls into the category of truly stupid mistakes, but heh, we all make 'em from time to time, right?

Oh well - Rev 3.000000001 anyone?

Sounds like you must be using a TO-220 voltage regulator chip.

Why not just use a TO-220 mouting kit with the mica wafer or thermally conductive rubber?

Of course I'm not feeling exactly brilliant myself after that Delrin mess.

Darlene

Genesis · 18th April 2006, 04:03

Its actually a PPAK (a funky TO-220FP derivitive). Surface-mount (the only SMT chip on the board; I can still hand-solder with enough precision for this one....

) - I chose it for a number of reasons, including very low drop out and the ability to run an inhibit (which is a cute option), along with a wide supply range (up to 16V, allowing use of a dive light can battery if you want, or a nominal 6V supply, etc.) When "off" it only pulls 50ua, which makes for some interesting possibilities for a "soft" power switch or a hard watchdog. It also only needs 2.2uf on the output for stability (much nicer than some of the others out there that want much higher values for an output filter cap)

Its available in regular TO-220 and 220FP as well, but without the inhibit (no pin for it to come out on.) The regular TO-220 package is just too damn big.

Oh, its also nice and cheap.

http://www.st.com/stonline/books/pdf/docs/2574.pdf

Scuba_Vixen · 18th April 2006, 04:17

Quote: (Originally Posted by Genesis)

Its actually a PPAK (a funky TO-220FP derivitive). Surface-mount (the only SMT chip on the board; I can still hand-solder with enough precision for this one....

) - I chose it for a number of reasons, including very low drop out and the ability to run an inhibit (which is a cute option), along with a wide supply range (up to 16V, allowing use of a dive light can battery if you want, or a nominal 6V supply, etc.) When "off" it only pulls 50ua, which makes for some interesting possibilities for a "soft" power switch or a hard watchdog. It also only needs 2.2uf on the output for stability (much nicer than some of the others out there that want much higher values for an output filter cap)

Its available in regular TO-220 and 220FP as well, but without the inhibit (no pin for it to come out on.) The regular TO-220 package is just too damn big.

Oh, its also nice and cheap.

http://www.st.com/stonline/books/pdf/docs/2574.pdf

Nice find,

Is it also practical to run one of those as a solenoid driver using the inhibit as the control? Overcurrent shutdown is already built in.

Darlene

17th April 2006, 21:45	#1 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,453	Ok, I feel like a total idiot...... :) Ever have one of those days? I got the R3 PC boards in while we were out of town. Was out Mousing around with my daughter. Anyway, on our return last night I had a look and set about to build up a couple so I can continue my integration. Anyway, I built up a head board, no problems found. Inspection looked good, everything fits, etc. Started on the CPU board and immediately saw a problem. I had foolishly laid a power trace under the voltage regulator chip. Now this would not be a problem - if the trace hadn't been on the same layer as the chip! But it is, and the nasty part is that the "tab" that provides heat sink (and ground) runs all the way under the bottom. So - this would be a nice direct power to ground short. Crap. Needless to say that board didn't get built up last night...... this falls into the category of truly stupid mistakes, but heh, we all make 'em from time to time, right? Oh well - Rev 3.000000001 anyone? __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
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17th April 2006, 22:06	#2 (permalink)
dantheman Emoticonoclast Current Rebreather/s: Sport Kiss rEvo Other Rebreather/s: Classic Kiss rEvo Join Date: May 2005 Location: NorthEast USA Posts: 397	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by Genesis) ... I had foolishly laid a power trace under the voltage regulator chip... I hate it when I do that ... --dan (who works at a level of abstraction above electrons)
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17th April 2006, 22:56	#3 (permalink)
steevke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Sport Kiss Join Date: Jul 2005 Location: Belgium Posts: 317	Re: Ok, I feel like a total idiot...... :) Try using a 'decent' PCB layout package (eagle e.g. which is free for small boards). A standard electrical rule check catches these errors without any problem. Steven
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17th April 2006, 23:05	#4 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 837	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by steevke) Try using a 'decent' PCB layout package (eagle e.g. which is free for small boards). A standard electrical rule check catches these errors without any problem. Steven Got a link to this? __________________ Never forget that life is a finite resource.
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17th April 2006, 23:07	#5 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,453	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by steevke) Try using a 'decent' PCB layout package (eagle e.g. which is free for small boards). A standard electrical rule check catches these errors without any problem. Steven Eagle is IMHO a royal pain in the butt..... __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
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17th April 2006, 23:51	#6 (permalink)
jdz Prism Cave Diver Current Rebreather/s: Prism Topaz Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Feb 2005 Location: Melbourne Australia Posts: 223	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by Sutty) Got a link to this? Hi there.. start here... http://www.cadsoft.de/freeware.htm Cheers, JDZ
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18th April 2006, 00:01	#7 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 837	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by jdz) Hi there.. start here... http://www.cadsoft.de/freeware.htm Cheers, JDZ Thanks for that __________________ Never forget that life is a finite resource.
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18th April 2006, 03:44	#8 (permalink)
Scuba_Vixen e/mCCR Dolphin Pilot Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: May 2005 Location: St. Croix USVI Posts: 557	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by Genesis) Ever have one of those days? I got the R3 PC boards in while we were out of town. Was out Mousing around with my daughter. Anyway, on our return last night I had a look and set about to build up a couple so I can continue my integration. Anyway, I built up a head board, no problems found. Inspection looked good, everything fits, etc. Started on the CPU board and immediately saw a problem. I had foolishly laid a power trace under the voltage regulator chip. Now this would not be a problem - if the trace hadn't been on the same layer as the chip! But it is, and the nasty part is that the "tab" that provides heat sink (and ground) runs all the way under the bottom. So - this would be a nice direct power to ground short. Crap. Needless to say that board didn't get built up last night...... this falls into the category of truly stupid mistakes, but heh, we all make 'em from time to time, right? Oh well - Rev 3.000000001 anyone? Sounds like you must be using a TO-220 voltage regulator chip. Why not just use a TO-220 mouting kit with the mica wafer or thermally conductive rubber? Of course I'm not feeling exactly brilliant myself after that Delrin mess. Darlene
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18th April 2006, 04:03	#9 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,453	Re: Ok, I feel like a total idiot...... :) Its actually a PPAK (a funky TO-220FP derivitive). Surface-mount (the only SMT chip on the board; I can still hand-solder with enough precision for this one.... ) - I chose it for a number of reasons, including very low drop out and the ability to run an inhibit (which is a cute option), along with a wide supply range (up to 16V, allowing use of a dive light can battery if you want, or a nominal 6V supply, etc.) When "off" it only pulls 50ua, which makes for some interesting possibilities for a "soft" power switch or a hard watchdog. It also only needs 2.2uf on the output for stability (much nicer than some of the others out there that want much higher values for an output filter cap) Its available in regular TO-220 and 220FP as well, but without the inhibit (no pin for it to come out on.) The regular TO-220 package is just too damn big. Oh, its also nice and cheap. http://www.st.com/stonline/books/pdf/docs/2574.pdf __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
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18th April 2006, 04:17	#10 (permalink)
Scuba_Vixen e/mCCR Dolphin Pilot Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: May 2005 Location: St. Croix USVI Posts: 557	Re: Ok, I feel like a total idiot...... :) Quote: (Originally Posted by Genesis) Its actually a PPAK (a funky TO-220FP derivitive). Surface-mount (the only SMT chip on the board; I can still hand-solder with enough precision for this one.... ) - I chose it for a number of reasons, including very low drop out and the ability to run an inhibit (which is a cute option), along with a wide supply range (up to 16V, allowing use of a dive light can battery if you want, or a nominal 6V supply, etc.) When "off" it only pulls 50ua, which makes for some interesting possibilities for a "soft" power switch or a hard watchdog. It also only needs 2.2uf on the output for stability (much nicer than some of the others out there that want much higher values for an output filter cap) Its available in regular TO-220 and 220FP as well, but without the inhibit (no pin for it to come out on.) The regular TO-220 package is just too damn big. Oh, its also nice and cheap. http://www.st.com/stonline/books/pdf/docs/2574.pdf Nice find, Is it also practical to run one of those as a solenoid driver using the inhibit as the control? Overcurrent shutdown is already built in. Darlene
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