Liquid Level Sensor integration?

[sunfish]

I have a header tank with provision for a low fuel level warning sensor (Honeywell, I think). 12 volt power, about 15 mA draw, signal is high if no liquid present.

How hard would it be to hook this straight to the EMS and generate a warning tone or message as well as a visual indication of low fuel?

 

[N82rb]

if it outputs a high signal when empty, and low when not that is easy enough. connect it to open contact line and setup the icon and parameters for it.

bob

 

[mmarien]

You can use any of the general purpose EMS pins and configure it as a contact. The contacts are usually configured the opposite way to your sensor. Contacts sense five volts unless grounded. So just connecting it to the warning sensor may not work as it will sense a high (+5V) all the time. You need to add a resistor to draw the power low to indicate no warning (0-2.5V).

The contact is just a round button on the screen with a name below and message above the button. You can make the button any color depending on the condition. ie: GREEN for good and RED for warning. You can turn on the alarm for the contact, but I think all you will get is a generic "ENGINE MONITOR" audio message.

More discussion here: http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1321300594

 

[sunfish]

Thanks, I will test this solution before I install the sensor. I am also trying to think about the possibility of false positive alarms because a low header tank alarm means I have about Ten minutes to land the aircraft before fuel exhaustion.

thinking more about it, this alarm protects me from only four  conditions, poor/ stupid personal fuel management/theft, failed fuel gauges, mechanical tank failure or loss of fuel cap or failure to open the cross connect valve.