When you're doing these experiments, don't forget about "Load Dump",
which is a very common problem on vehicles and is caused by things
like the stored energy in a motor's windings being dumped back into
the 12V electrical bus when the bus power is removed. This fed-back
voltage can approach hundreds of volts and can destroy components
that are not designed to handle it.
http://en.wikipedia.org/wiki/Load_dump
mike
----
On Aug 6, 2008, at 3:35 PM, Ivar Janmaat wrote:
Thanks,
I already feel much better....
I also wouldn't be suprised if the Sun ray can handle voltage range
of 10
to 15 Volts without problems. All hardware is designed to handle power
fluctuations around the specified Voltage (12 Volts).
I have taken apart a Sun Ray 2 to look for the voltage regulators and
found some made by philips however I could not find the
specifications of
them yet.
The 270 I did not try to dismantel yet because the tft screen might
complicate things a bit.
Ivar
I feel your pain, Ivar... The problem is that most people on this
list are
not hardware engineers... :p
The question is how regulated that 12V needs to be before it hits the
SunRay. Here's an experiment for you all: take any regular linear
power
supply (not regulated) and stick a multimeter on it. You'll notice
that
the
voltage you measure is higher than what it's rated: it'll say 9V,
but it
measures (unloaded of course) around 12V. Put a load on it, and the
voltage
will fluctuate. So, if the component cares about a precise
voltage, it's
doing some internal regulation. The question here is what the
bounds on
that
internal regulation are...
Now, the SunRay powersupply is of the switching variety, which
will ensure
it stays a lot closer to 12V than a plain old linear. The SunRay
engineers
may have put in little on-board regulation with this in mind, or
they may
have put in something that can handle a few volts over (or under).
Personally, I'd be surprised if it couldn't handle 15V peaks, but
this
question needs to be answered either by a SunRay engineer or by
someone
who
has taken apart a SunRay and can identify the power supply
regulator part
number...
Anthony
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jason
Winningham
Sent: August-06-08 7:05 AM
To: SunRay-Users mailing list
Subject: Re: [SunRay-Users] Re: Sun Ray on my boat
On Aug 5, 2008, at 4:27 PM, Sridhar Ayengar wrote:
Ivar Janmaat wrote:
Its such a waste of time to revers engineer power specs.....
The voltage and polarity you can get with a simple multimeter. I
doubt you even need to know the current requirements, as you're
probably going to overspecify it by a wide margin, right?
It's not even that complex - the sunray2 power supply on my desk says
"12V 2.5A" and a figure indicating center positive on the label. I'm
gonna go out on a limb and say you need 12V and 2.5A. (:
-Jason
----------------------------------------
Jason Winningham
Computer Systems Engineer
College of Engineering
The University of Alabama in Huntsville
http://support.eng.uah.edu/ http://www.eng.uah.edu/~jdw
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