Further to my message of 21 July, I have had the following very helpful
input from John Moran, which I pass on with his permission.
"I have substituted a LED/1N4004/680ohm resistor for the specified bulb and
it
seems to work fine, at least in the short run-time so far. It lights bright
prior to start and shuts off nicely once the engine is running. The EIS
indicates that the system voltage is 13v or so and rising slowly over time
as
the battery charges, which agrees with the LED indication. There is no
indication of a dim output as might be encountered with a leaky drive
circuit. I realize that one installation is anecdotal and not proof that it
will work in other units, so am interested to know if you have experienced
problems which would thus indicate that my approach is marginal. (Wouldn't
it
be nice if ROTAX would share the regulator schematic so we could all make
informed choices?)
"Interestingly, I did have trouble with the warning lamp from the EIS which
also called for a 3w bulb; a 6.8k pullup solved that problem, eliminating
the
dim background under the no-fault condition."
If anyone else has experience of using this or another circuit in place of
the 12v/3W lamp recommended by Rotax for low-voltage warning, please would
they share it on this net.
The sole purpose of the circuit is to provide a safe and reliable
indication: if this can be done in a way that uses less power or is more
compatible with other indicators on your panel, then I shall be happy to
recommend it.
Fly safely
Mike
|