At 04:20 08 April 2020, 2G wrote:
On Tuesday, April 7, 2020 at 8:58:53 PM UTC-7, 2G wrote:
On Tuesday, April 7, 2020 at 8:06:46 PM UTC-7, Andy Blackburn wrote:
I put a power resistor in the circuit to keep the current surge down.
I=
undersized the capacitor so if I mess up on the with rotation I can lose
p=
ower. Typically I'll shut off some non-essential equipment to lower the
dra=
w if I really don't want a computer reset.
=20
Andy
=20
On Sunday, April 5, 2020 at 8:45:30 AM UTC-7, jfitch wrote:
=20
What is the inrush current when you first switch the power on? Must
n=
ot be enough to blow the fuse, but that'd be something I'd want to
O'scope
=
with a current probe.
=20
You didn't say what the resistor size was. There is already a resistor
in=
the circuit - it is called the internal resistance of the battery,wiring
r=
esistance, switch contact resistance and the equivalent series resistance
(=
ESR) of the capacitor.

I forgot to mention that aluminum electrolytic capacitors have very
signifi=
cant inductance at frequencies above 10 KHz. Inductance (also called a
chok=
e because they choke off current) limits inrush current. The joules of
ener=
gy being transferred is pretty low (about 0.6 J), but I have no problem
wit=
h adding a small series resistor (1 ohm - don't worry about the wattage
as
=
very little power is supplied by the cap).

Tom

Has anyone reported this problem to LXV, and if so what was their response
please? There seems to be an opportunity for a firmware fix to this
problem, not requiring any additional hardware.

In the specification for Flight Recorders, a new IGC file is not started if
power has been interrupted for less than one minute. This is to allow a
change of battery, breaker reset or change a fuse. Exactly the problem we
are discussing.

If the LX firmware were enhanced to inhibit re-calculating QNH where power
has been lost for less than n seconds, this problem goes away.

Discuss.