2N3904 maximum ratings Vceo Vcbo

[John Larkin]

On Sun, 10 May 2015 04:46:51 +0000 (UTC), mroberds@att.net wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:
It's probably OK at 15, since I don't expect anybody to stall it, but
it's weird. We'll get some 24 volt versions to test.

Toss in a couple of 1N4001s (or surface-mount equal) in series with the
fan connector and get on down the road.

But the original board, rev A, first try, works with no kluges.
Hacking it would be a sin.

https://dl.dropboxusercontent.com/u/53724080/PCBs/P350_SN1.JPG


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

John Larkin <jlarkin@highlandtechnology.com> wrote:

On Sun, 10 May 2015 04:46:51 +0000 (UTC), mroberds@att.net wrote:
John Larkin <jlarkin@highlandtechnology.com> wrote:

It's probably OK at 15, since I don't expect anybody to stall it,
but it's weird. We'll get some 24 volt versions to test.

Toss in a couple of 1N4001s (or surface-mount equal) in series with
the fan connector and get on down the road.

But the original board, rev A, first try, works with no kluges.
Hacking it would be a sin.

I think that about my code when all the modules are still sitting around
version 0.x. Usually, by the time it ships, some modules are up to 1.5
or more. The beauty is still there, but you have to look past the cruft
to see it.

Stick the diodes in the fan harness?

Matt Roberds

 

[Phil Hobbs]

On 5/10/2015 1:19 AM, John Larkin wrote:

On Sun, 10 May 2015 04:46:51 +0000 (UTC), mroberds@att.net wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:
It's probably OK at 15, since I don't expect anybody to stall it, but
it's weird. We'll get some 24 volt versions to test.

Toss in a couple of 1N4001s (or surface-mount equal) in series with the
fan connector and get on down the road.

But the original board, rev A, first try, works with no kluges.
Hacking it would be a sin.

https://dl.dropboxusercontent.com/u/53724080/PCBs/P350_SN1.JPG

Couldn't you get Avnet to change their colour scheme? It clashes
horribly.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[John Larkin]

On Sun, 10 May 2015 13:02:04 -0400, Phil Hobbs
<hobbs@electrooptical.net> wrote:

On 5/10/2015 1:19 AM, John Larkin wrote:
On Sun, 10 May 2015 04:46:51 +0000 (UTC), mroberds@att.net wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:
It's probably OK at 15, since I don't expect anybody to stall it, but
it's weird. We'll get some 24 volt versions to test.

Toss in a couple of 1N4001s (or surface-mount equal) in series with the
fan connector and get on down the road.

But the original board, rev A, first try, works with no kluges.
Hacking it would be a sin.

https://dl.dropboxusercontent.com/u/53724080/PCBs/P350_SN1.JPG

Couldn't you get Avnet to change their colour scheme? It clashes
horribly.

Cheers

Phil Hobbs

Think so? I kind of like it. But then, I have a red car and I'm typing
in a red t-shirt.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Sun, 10 May 2015 06:18:04 +0000 (UTC), mroberds@att.net wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:
On Sun, 10 May 2015 04:46:51 +0000 (UTC), mroberds@att.net wrote:
John Larkin <jlarkin@highlandtechnology.com> wrote:

It's probably OK at 15, since I don't expect anybody to stall it,
but it's weird. We'll get some 24 volt versions to test.

Toss in a couple of 1N4001s (or surface-mount equal) in series with
the fan connector and get on down the road.

But the original board, rev A, first try, works with no kluges.
Hacking it would be a sin.

I think that about my code when all the modules are still sitting around
version 0.x. Usually, by the time it ships, some modules are up to 1.5
or more. The beauty is still there, but you have to look past the cruft
to see it.

Code can be, and often is, edited and recompiled scores, maybe
hundreds of times, before people decide that it's good enough, or that
it has to ship. Code doesn't have pads that fall off after a dozen
reworks. A PC board can't be edited and re-etched in 10 minutes;
iterations take more like a month, and are messy and expensive and
publically embarassing. Electronic design has to be done right, and
brutally checked, at the engineering level, before the Gerbers are
formally released and boards ordered and assembled and tested.

In general, the easier it is to change something, the less care will
go into its design, and the more it will get changed. And the more
bugs will never get fixed.

Stick the diodes in the fan harness?

We could, a 3 volt zener or a resistor in a bit of shrink tubing. Or
just run a 12 volt fan at 15 volts! That looks like it will work.

Our FPGA surface temp is over 100C, and the box quits working at 80 to
85C ambient. We could sell that, but we'd prefer a little more margin.

That red uZed board has a couple of holes for mounting a tiny fan
above the FPGA. We may do that, as opposed to trying to cool the
entire box.



--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Sun, 10 May 2015 12:14:22 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

On Sun, 10 May 2015 06:18:04 +0000 (UTC), mroberds@att.net wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:
On Sun, 10 May 2015 04:46:51 +0000 (UTC), mroberds@att.net wrote:
John Larkin <jlarkin@highlandtechnology.com> wrote:

It's probably OK at 15, since I don't expect anybody to stall it,
but it's weird. We'll get some 24 volt versions to test.

Toss in a couple of 1N4001s (or surface-mount equal) in series with
the fan connector and get on down the road.

But the original board, rev A, first try, works with no kluges.
Hacking it would be a sin.

I think that about my code when all the modules are still sitting around
version 0.x. Usually, by the time it ships, some modules are up to 1.5
or more. The beauty is still there, but you have to look past the cruft
to see it.

Code can be, and often is, edited and recompiled scores, maybe
hundreds of times, before people decide that it's good enough, or that
it has to ship. Code doesn't have pads that fall off after a dozen
reworks. A PC board can't be edited and re-etched in 10 minutes;
iterations take more like a month, and are messy and expensive and
publically embarassing. Electronic design has to be done right, and
brutally checked, at the engineering level, before the Gerbers are
formally released and boards ordered and assembled and tested.

In general, the easier it is to change something, the less care will
go into its design, and the more it will get changed. And the more
bugs will never get fixed.



Stick the diodes in the fan harness?

We could, a 3 volt zener or a resistor in a bit of shrink tubing. Or
just run a 12 volt fan at 15 volts! That looks like it will work.

Our FPGA surface temp is over 100C, and the box quits working at 80 to
85C ambient. We could sell that, but we'd prefer a little more margin.

That red uZed board has a couple of holes for mounting a tiny fan
above the FPGA. We may do that, as opposed to trying to cool the
entire box.

This rig lets us run up to 90C ambient. The guy who tested it wimped
out there; I'd have cranked up the temp until something failed.

https://dl.dropboxusercontent.com/u/53724080/Thermal/FPGA_Fan.JPG

There is an on-chip temp sensor in the ZYNQ, but we'd need an FPGA
compile and some ARM code to access it, which isn't in the budget just
now. Maybe next iteration.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com