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Date: Mon, 25 Feb 2008 13:48:56 -0700
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EM2 Warning light
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Hi Bill,

My manual says to connect the + side to 12V unless the lamp requires a
different voltage.  The output pulls the indicator light to ground, so
it shouldn't matter if it's hooked to +12 or +5.

If using an LED, a series resistor is required to limit the current.
The LED's that are rated at 12V have a built in resistor so an external
one isn't needed.  A typical LED will have a maximum current rating of
around 30 ma and that may be too bright especially at night.

Something like a 600 ohm resistor would limit the current to between 15
and 20 ma.  There is approximately 2 volt drop across the diode and the
bus voltage varies by several volts so the actual current will vary
also.  A smaller or larger resistor can be used to adjust the
brightness.  (Check the specs for the LED you use of course.)

Bob W.

On Mon, 25 Feb 2008 20:05:49 +0000
wschertz@comcast.net wrote:

> Check the manual -- I believe that the warning light should be connected to a 5 volt source. At least if using LED's. An LED will glow all the time if fed with 12V, but if it is incandescent, it won't light up. The EM-2 connects to ground when alarming
> Bill Schertz
>  -------------- Original message ----------------------
> From: Bob White <bob@bob-white.com>
> > Hi Bob,
> > 
> > It sounds like a wiring problem.  The warning light should be connected
> > to the 12V bus on one side, and the other side is connected to the wire
> > from the EM2. If it's an LED, then polarity of the LED is important too.
> > 
> > When a reading is out of spec on the EM2, the reading also flashes.
> > That continues even when the ACK button is pushed.  Are you seeing any
> > of the readings flash off and on on the EM2 display?
> > 
> > Bob W.
> > 
> > On Mon, 25 Feb 2008 10:13:49 -0500
> > bmears9413@aol.com wrote:
> > 
> > > I dont have a warnig light hooked directly to the alternator. I understand 
> > that if any display on my EM2 is out of "spec"..the display will flash and the 
> > warning light from the EM2 will light up untill you press the ACK button. My 
> > warning light never lights up...for any reason so far.
> > > 
> > > Bob Mears
> > > 
> > > 
> > > -----Original Message-----
> > > From: Bob White <bob@bob-white.com>
> > > To: Rotary motors in aircraft <flyrotary@lancaironline.net>
> > > Sent: Sun, 24 Feb 2008 11:02 pm
> > > Subject: [FlyRotary] Re: EM2 Warning light
> > > 
> > > 
> > > 
> > > Hi Bob,
> > > 
> > > Warning light connected to the alternator?  It should come on when you
> > > power up and go out when the alternator starts putting out.  If it's the
> > > warning light from the EM2, it should start flashing when anything goes
> > > out of it's range, and that's practically all the time when you're fist
> > > setting it up.  If It's not coming on at all it sounds like something
> > > isn't hooked up right.
> > > 
> > > On your water pressure, it should come up to cap pressure at the most.
> > > Do you have an air cushion in your system.  If not, the pressure will
> > > go pretty high because of liquid expansion until a little liquid is
> > > pushed into the overflow tank.  23 psi isn't going to hurt the engine,
> > > but the EM2 calibration needs to be checked also.  I was able to rent a
> > > cooling system pressure tester from AutoZone which helped with the
> > > calibration.
> > > 
> > > Bob W.
> > > 
> > > 
> > > On Sun, 24 Feb 2008 23:46:39 EST
> > > BMears9413@aol.com wrote:
> > > 
> > > > Is there a test mode on the EM2 warning lamp? My alternator is only putting  
> > > > out 12.6 volts and my EM2 has the voltage flashing, as it should. But my 
> > > > warning  light doesn't light up. Shouldn't it? It hasnt lit up yet, even 
> > with 
> > > the 
> > > > engine  not started and 0 oil pressure.
> > > >  
> > > > Bob Mears 
> > > > Supermarine Spitfire.
> > > >  
> > > > 
> > > > 
> > > > 
> > > > **************Ideas to please picky eaters. Watch video on AOL Living.      
> > > > 
> > (http://living.aol.com/video/how-to-please-your-picky-eater/rachel-campos-duffy/
> > > > 2050827?NCID=aolcmp00300000002598)
> > > > 
> > > 
> > > 
> > 
> > 
> > -- 
> > N93BD - Rotary Powered BD-4 - http://www.bob-white.com
> > 3.8 Hours Total Time and holding
> > Cables for your rotary installation - http://roblinstores.com/cables/
> > 
> > --
> > Homepage:  http://www.flyrotary.com/
> > Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html
> 
> 
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html


-- 
N93BD - Rotary Powered BD-4 - http://www.bob-white.com
3.8 Hours Total Time and holding
Cables for your rotary installation - http://roblinstores.com/cables/