Cambridge 302 USB Port

Paul,

Here's the deal: the back of my Ipaq 3950 says 5VDC, 2 amps.

The 302 docs tell us we are limited to 0.9 amp out of the 302.

You, and others, have led us into a marginal solution. I think you
ought to quit doing that :-).

I have about 500 hours of *mostly* trouble free PDA operation off my
302... because I *mostly* remember to have the the PDA at full
charge. I've sometimes forgotten (mostly during a two day drive
somewhere) and then had mysterious problems with the 302 (mostly 1200
miles from home). I finally read the manual (again). It's easy to
miss stuff in the 302 manual because of the way it isn't really
organized.... but here it is (smites brow).

The correct solution for anyone with a PDA is to ensure that the power
supply is up to the task. The 302 isn't by any reasonable engineering
definition.

Here's a $12 start to a proper engineering solution
http://www.murata-ps.com/data/meters...8sr-2a_a00.pdf

Get 'em at Mouser. Input fuse is a good idea.

-Evan Ludeman / T8


On Dec 7, 5:10*pm, "Paul Remde" wrote:
Hi,

I'm sorry, but I must respectfully disagree with your comment about the 302
not being able to power a PDA. *I have used many different PDAs with a 302
for years with no problems. *I think customers have problems when they
connect a PDA with the PDA's battery low. *PDAs with low batteries can draw
a LOT of current (over 1 A). *The 302 can supply plenty of current for all
PDAs and PNAs I've seen - as long as they are fully or nearly fully charged.

Paul Remde
Cumulus Soaring, Inc.

"GK" wrote in message

...
Will the DB-9 port provide power to the PDA?

- Yes and no. The power source from C302 is problematic, especially
when the battery on your PDA is charging. I have seen my C302 freezing
and working erratically under those circumstances. It’s better if you
provide the power via the power converter directly from your glider's
battery.
* * *The USB port on the C302 is pretty much useless since you have to
switch communication between serial and the USB with a dip switch
which is located at the back of the C302. In my case its still
requires taking the canopy off to reach the back side of the C302
anytime I like to use the USB port. You can also download flight logs
and declare the task via the PDA serial communication and gliding
softwa Winpilot(and a small program you can obtain for free from
Cambridge aero) or the Connect me from seeyou.

GK

On 12/9/2011 7:59 AM, T8 wrote:
Paul,

Here's the deal: the back of my Ipaq 3950 says 5VDC, 2 amps.

The 302 docs tell us we are limited to 0.9 amp out of the 302.

You, and others, have led us into a marginal solution. I think you
ought to quit doing that :-).

I have about 500 hours of *mostly* trouble free PDA operation off my
302... because I *mostly* remember to have the the PDA at full
charge. I've sometimes forgotten (mostly during a two day drive
somewhere) and then had mysterious problems with the 302 (mostly 1200
miles from home).

The back of my 3850 also says 5 vdc, 2 amps, but in 1200 hours/250
flights of use, I've never had a problem with it and my 302. At home, it
goes from the charging stand to the glider, but while traveling, it can
be 4 or 5 or more days between flights - still no problem.

Maybe my 3850 doesn't draw as much as a 3950, maybe your 3950 has a
battery problem so it's getting too low, too quickly, maybe there is a
problem with your 302 - can't tell - but I would not conclude it's a
marginal solution.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Dec 9, 2:00*pm, Eric Greenwell wrote:
On 12/9/2011 7:59 AM, T8 wrote:

Paul,

Here's the deal: *the back of my Ipaq 3950 says 5VDC, 2 amps.

The 302 docs tell us we are limited to 0.9 amp out of the 302.

You, and others, have led us into a marginal solution. *I think you
ought to quit doing that :-).

I have about 500 hours of *mostly* trouble free PDA operation off my
302... because I *mostly* remember to have the the PDA at full
charge. *I've sometimes forgotten (mostly during a two day drive
somewhere) and then had mysterious problems with the 302 (mostly 1200
miles from home).

The back of my 3850 also says 5 vdc, 2 amps, but in 1200 hours/250
flights of use, I've never had a problem with it and my 302. At home, it
goes from the charging stand to the glider, but while traveling, it can
be 4 or 5 or more days between flights - still no problem.

Maybe my 3850 doesn't draw as much as a 3950, maybe your 3950 has a
battery problem so it's getting too low, too quickly, maybe there is a
problem with your 302 - can't tell - but I would not conclude it's a
marginal solution.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Or maybe this is exactly the sort of behavior that can be expected
when ratings are exceeded. Occasional failures in some, but not all
devices. It could be installation and environment dependent, too.

-Evan Ludeman / T8