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Message
I have an LED (designed for 12V) wired
up for the alarm light, and it comes on (not flashing, steady) at what seems to
be about half brightness when power is applied to the EM-2.
Hi
Bill,
I had
the exact same problem with the current EM-2 (all in one), but not with the
earlier one (separate electronics box). In both cases, I used the exact
same super bright LED's from the Shack of Rat.
In
talking to Tracy, my understanding is that the alarm signal pin is on a 5V pull
up, with a 10k ohm resistor. When the EM-2 wants the light on, it grounds
the pin, but when it's "off", the pin would be sitting at 5V. If you tie
the light to 12V, then there's a 7V potential across the light, with a 10k ohm
resistor in series. This will allow some current to flow, and would
probably not be noticeable on an incandescent lamp, but for LED's, it will
appear to be on, but dim.
The fix
was to use one of the EM-2 5V outputs for the LED alarm light power.
This gives no voltage differential when the light is supposed to be off,
and 5V differential when on.
If you
are using a pre-packaged LED that's made for 12V, and you use 5V instead,
it will work but will be dimmer than it would have been with
12V. You may have to use a different LED.
Tracy
may also have a better answer now, so stand by for the real answer
:-)
Cheers,
Rusty
(single rotor engine currently installed on the hanger
floor)
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