Powering engine sensors

[BlueCH750]

Starting to wire up my engine sensors to the EMS 220 module.  The CHT and EGT seem straight forward.  For the other sensors; Red cubes FT60 (2), engine oil pressure, fuel pressure I need to provide power and ground for them to output signal into the EMS 37 pin harness.  Can I utilize the aux volt outputs of the EMS (Pin 15 or 18) to provide power to the sensors, and if so, can I put them all on the same junction?  Same with ground?  Looking for ideas and best practices.  Thanks!  Dave

 

[Raymo]

I used pin 18 (white/red) for all the 5v sensors on the engine. I don't think there is another way to power them all (oil pres, fuel pres, oil temp, etc). Don't recall if I used a common ground pin.

 

[ned]

The red cubes need 12v power unlike the engine sensors that require 5v

 

[BlueCH750]

Thanks for the replies...understand about the 12V for the FT-60's.  The Dynon manual is clear regarding acceptablility of using same power source and ground for like required voltage sensors.  My follow on question would be this:  Does one typically just bring the EMS provided voltage wire thru the firewall and connect to all the like voltage sensors at a common point; e.g. one big splice?  How about a pigtail off the EMS power wire with a 9 pin dsub connector for the sensors power, likewise for grounds?  Again, kind of looking for typical best practices on how to do this.  I'll also need to power some ray allen servos and potentiometers from the 5V EMS pin as well  Thanks!  Dave

 

[Raymo]

The answer to the follow-on question will be very opinionated. I chose to bring the one wire through the firewall and spice it out to sensors at different points (not one big splice) via solder and heat shrink. A DB-9 in the engine compartment, IMO, would not be wise due to heat.

The Ray Allen servos (also 12v) should NOT be powered through the EMS. You would power them from your main or essential bus, depending on your setup.

 

[BlueCH750]

Thanks Ray, re: Ray Allen servos...I meant to say that I will or may need the 5V for my position sensors output of the trim servo and my position sensor for the flaps.  Does that sound correct?  The servo does indeed take 12V for power, but I am bypassing any indicator typically used (i.e.; the RP3 LED indicator) and inputting directly to the Dynon for trim indication.  It seems I need 5V to do that.  Same for the Ray Allen position sensor (POS) I will use to indicate flap position on the Dynon.  Open to overlooked considerations!!

Thanks!  Dave

 

[Raymo]

Dave,

The position sensor wires can be fed into the EMS but do not require a separate power source or voltage.

I did a good bit of reading for my RV-7A before wiring and decided to omit the sensor wire connections for flaps and trim. Most folks that hooked them up said they almost never look at the trim position on the EFIS.

 

[BlueCH750]

Thanks Ray, I will revisit the POS diagram on the Ray Allen site. Understand about flap position...I can look out my door and see where they are at! Trim I cannot, and might like to be able to set a neutral or take-off setting during checklist prior to start. Something to think about anyway. Appreciate the dialog!! Dave

 

[airguy]

With almost a year of flying on my new 9A where I put the trim position on the Skyview display, I can tell you that I believe I have looked at the trim position maybe twice. Obviously different aircraft are going to have different needs for accurate takeoff trim, but the RV series is not very demanding in that respect.